2015-09-02 by cliofreak@yahoo.com
HI people!
I have a Polysix with an annoying noise. It can be seen in this video. I was sold the synth and told the battery had been done. I looked anyway and some repair had been done in the past as some traces were rerouted. I noticed the battery was still there however (possibly a replacement that also leaked) and It was leaking. I replace it with the CR2032 mod and all patches still work and load/save etc but the synth has this noise! Any ideas. All the old trace work seems to be fine...continuity checks etc. Help! Please! This synth has the potential to sound AWESOME!
Noisy Polysix
Noisy Polysix This feature is not available right now. Please try again later.
Preview by Yahoo
2015-09-02 by cliofreak@yahoo.com
2015-09-02 by Florian Anwander
Hi
Appearently this is a frequency depending on the pressed keys. I am
quite sure, it will show a kind of tonal pattern each eight keys. Check
also, whether the frequency changes if you press any button or turn a
rotary switch on the frontpanel.
In general this sounds to me like digital and analog ground are mixed up
or that some ground is missing.
Now you may insist, that the schemo does not distinguish digital and
analog ground, but the routing on the KLM-366 appearently makes such a
difference. I'd check additional cables.
In regards of a missing ground, I'd have a look at the ground wire
connections between keyboard frame (not sure whether this is grounded),
housing shield and pcbs.
Florian
Am 02.09.2015 um 16:00 schrieb
cliofreak@yahoo.com [PolySix]:
>
> HI people!
>
>
> I have a Polysix with an annoying noise. It can be seen in this video.
> I was sold the synth and told the battery had been done. I looked
> anyway and some repair had been done in the past as some traces were
> rerouted. I noticed the battery was still there however (possibly a
> replacement that also leaked) and It was leaking. I replace it with
> the CR2032 mod and all patches still work and load/save etc but the
> synth has this noise! Any ideas. All the old trace work seems to be
> fine...continuity checks etc. Help! Please! This synth has the
> potential to sound AWESOME!
>
>
2015-09-02 by Florian Anwander
Now seeing your photos: repair all the ground traces around the battery.
These look extremely ugly.
2015-09-02 by cliofreak@yahoo.com
Hi yes it is a patten everry 8 notes chromatically
2015-09-02 by cliofreak@yahoo.com
Hi, yes it is showing a pattern every 8 notes chromatically
2015-09-02 by Eoin O'Callaghan
2015-09-02 by Florian Anwander
Am 02.09.2015 um 16:59 schrieb Eoin O'Callaghan
cliofreak@yahoo.com
[PolySix]:
> Here it is right now...
Ok, you did replace the battery but you did not repair the traces. This
has to be done first, before we try anything else.
2015-09-02 by Eoin O'Callaghan
The traces have been repaired. That big thick ground trace is showing continuity. I think its fine. I could be wrong but its showing continuity from main ground right to ground on a chip at bottom of this board.
2015-09-03 by cliofreak@yahoo.com
So I changed the IC and its all still the same. Exactly the same. Im now considering the KIWISIX but its expensive.
2015-09-03 by Florian Anwander
Am 02.09.2015 um 17:48 schrieb Eoin O'Callaghan
cliofreak@yahoo.com
[PolySix]:
> That big thick ground trace is showing continuity. I think its fine. I
> could be wrong but its showing continuity from main ground right to
> ground on a chip at bottom of this board.
Showing continuity and working satisfying as ground that can catchup
noise signals are two different things. This ground line MUST be as wide
as at the other places. I really recommend to clean it with a fiber
glass brush, and then resolder it over the total length.
2015-09-03 by Eoin O'Callaghan
Ok thanks, Ill give that a go
2015-09-03 by Eoin O'Callaghan
Yeah, cleaned the ground around the edge with a fibreglass pen and added solder to places that looked like it might need reinforcing. Ground is solid from the power source all the way to the battery board and even with traces all done and battery replaced and that IC chip near battery replaced...its exactly the same. Zero difference. Saving for the KIWI seems more and more likely. I pains me to wonder if even that might not fix it.
2015-09-04 by synthmans@gmail.com
You can choose to go with a replacement, either the Kiwi upgrade or a clone pcb requiring all the related transfer of old components and addition of newer....lots of work!
However, don't give up yet... if you've already 'cleaned the board', you may have removed subtle signs of damage due to corrosion. However, you may yet find telltale signs of 'oxidation/corrosion', however subtle, on vias and upper pads.
In particular, as per a post by another member battling his intermittent/ issues for over a year or more - he was told to look in the area of IC18 pin 11 of the digital board (HD14051 analog switch).
I did the same, and other than slight oxidation, the solder joint at the pin (component side) seemed okay, but a continuity test to the related track via (~ 1 inch away) showed otherwise - a complete open.
I think this particular area is a point of electrical attraction to the (ionic/charged?) battery vapor... The pcb annular rings are very small and so it doesn't take much corrosion to affect the pin/pad connection, particularly as there's not much copper to begin with.
So...check the topside component pads in this same area for any tell-tale dullness etc., use a continuity meter to verify the traces. Touch up as needed, if the solder doesn't take, it's a sign you need to attach a jumper wire, directly on the pin, back to a good point/via (not too far). Don't forget to resolder the bottom pads too.
Good Luck and post any question if you're not sure....
2015-09-04 by Eoin O'Callaghan
Thanks! I'll have a look at that area and consider all that you said re dullness vs continuity etc. Not giving in just yet.
2015-09-04 by <backshall1@bellsouth.net>
Do you have the keyboard cables tied up away from the circuit board? They
are supposed to be nicely bundled and attached to the back of the metal keybed
to keep them away from the KLM-367. Do you have a ground wire from the metal
foil sheet under the chorus board to the ground of the output jack? These are
just a couple of things that commonly cause noise, although I haven’t heard
anything quite like what was in your video.
Don B.
Sent: Thursday, September 3, 2015 8:43 PM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks! I'll have a look at that area and consider all that you said re
dullness vs continuity etc. Not giving in just yet.
2015-09-04 by synthmans@gmail.com
Yeah, those keyboard wires are like antennas carrying 'dirty' digital key scanning signals that can radiate into the analog electronics... if you've ever brought an old style LED/fluorescent calculator near an AM radio, you will get the idea. It would likely be a steady 'scanning'/buzzy noise...
Otherwise, it only takes one corroded connection at the points previously mentioned, to cause all sorts of intermittents & glitches...
2015-09-04 by Malte Rogacki
A complete shot in the dark here:
When watching the video it appeared to me as if the problem was not audible
for some patches (around 1:30 for example).
This of course would hint at a different problem, possibly with the voice
board or the effects board.
The "noise" frequency is dependent on the last (or highest? lowest?)
pressed key but will always jump back to the same frequency after the last
key is released. The frequency change seems to be inverted - higher key
presses result in a lower frequency.
In the video I don't really hear a pattern.
2015-09-04 by Eoin O'Callaghan
HI, there is actually a pattern every 8 notes chromatically. Every 8 notes create the same frequency but indeed, it does alway jump back to the same hands off frequency each time. Some patches are louder than others but that makes me thing its got something to do with whatever is engaged in said patch...VCO, VCA, VCF, PW, PWM or any other changeable parameter. When the patch is loud and buzzing 'organ' like, you can't hear any problem but as soon as you try to create a nice mellow pad, its too noisy to use. Especially if you change notes a lot because you end up with the sound of a crazy high pitched circus organ playing in the background.
2015-09-04 by Malte Rogacki
If it's the same pattern every 8 notes I'd suspect interference from the
key assigner.
I believe Dan Backshall already suggested checking the keyboard cable.
The key assigner is located on the voice board so it "leaking" into the
voices is a possibility.
Several wild guesses (again):
The noise volume clearly was modulated by the LFO hence it must be injected
somewhere before that part (VCA modulation happens on the effects board).
The difference in noise volume could be the result of different attenuator
settings; please check this. The attenuator circuitry is also on the
effects board.
You could check the signal directly at the voice board output and see if
there's already noise.
I seem to recall that there actually was a field modification to keep the
keyboard cable away from the other boards because it would interfere. The
keyboard cable is fastened to the frame in two locations (with a clip and
with a wire); if one of them went missing it could result in some strange
behaviour.
You could try to remove the keyboard and check if the noise changes if you
move it a couple of inches away (while still being connected).
There could also be a problem with the effects board. Depending on the
damage to the processor board (and how the Polysix was stored) the damage
could have spread to the effects board right next to the battery. I have
seen several acid-damaged effects boards.
2015-09-04 by synthmans@gmail.com
That's what my synth was doing before I repaired the bad connection I'd mentioned.... it would kick in intermittently with all kinds of 'strange noise' symptoms from the effects, filter etc. Very simply, because that point in question (analog switch connection) was a common control voltage point, it affected all those areas....
Do yourself a favor, please check it out as mentioned earlier before you get caught up in distraction/analysis because the symptoms are seemingly 'complex' for a very very basic issue of an open/intermittent....
You have to remember that these machines are totally dependent on scanning and distributing analog control voltages.... you sabotage that and the whole synth goes out of whack with all kinds of oddities. Otherwise, looking at it with blinders, I would have been faulting the effects unit, the filter unit etc. - again, can't overstate it, that one point was the crux of the whole 'gremlins' issue.
2015-09-04 by Eoin O'Callaghan
hey, Im trying to find the 'digital board' but eveything is KLM... etc
2015-09-04 by Eoin O'Callaghan
2015-09-04 by cliofreak@yahoo.com
Anyone know where to find IC18 in question. Ive the whole thing opened up and all I can see are 8 pin IC 18s so can't check pin 11
2015-09-04 by <backshall1@bellsouth.net>
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by Eoin O'Callaghan
Thanks, well IC18 on the 367 board is fine on pin 11 and the others, however IC18 on 366 is not fine. In fact a bunch of previous re-tracing has been done on it and currently pin 11 is not showing continuity. I dunno if you meant me to check IC18 on the 366 board?
On Friday, September 4, 2015 2:19 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by cliofreak@yahoo.com
Just repaired pin 11...fingers crossed...
2015-09-04 by <backshall1@bellsouth.net>
It looks like IC18 on the 366B is a TL072 (8-pin chip) in the tuning
circuit. He was definitely talking about the 367 board, where IC18 is the 14051
demultiplexer for the filter and envelope control voltages. Pin 11 is one of the
address lines that control it. Neither of them seem to be the kind of thing that
would cause the type of noise you are hearing. Can you upload a picture of the
top of the board, showing the chip you are working on?
Don B.
Sent: Friday, September 4, 2015 9:32 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks, well IC18 on the 367 board is fine
on pin 11 and the others, however IC18 on 366 is not fine. In fact a bunch of
previous re-tracing has been done on it and currently pin 11 is not showing
continuity. I dunno if you meant me to check IC18 on the 366 board?
On Friday, September 4, 2015 2:19 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by Eoin O'Callaghan
Ive put it together again and its exactly the same. 367 chip 18 is fine. The chip I was working on is the one right beside the battery except on the next board (366). Its a HD14069UBP
On Friday, September 4, 2015 3:02 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
It looks like IC18 on the 366B is a TL072 (8-pin chip) in the tuning
circuit. He was definitely talking about the 367 board, where IC18 is the 14051
demultiplexer for the filter and envelope control voltages. Pin 11 is one of the
address lines that control it. Neither of them seem to be the kind of thing that
would cause the type of noise you are hearing. Can you upload a picture of the
top of the board, showing the chip you are working on?
Don B.
Sent: Friday, September 4, 2015 9:32 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks, well IC18 on the 367 board is fine
on pin 11 and the others, however IC18 on 366 is not fine. In fact a bunch of
previous re-tracing has been done on it and currently pin 11 is not showing
continuity. I dunno if you meant me to check IC18 on the 366 board?
On Friday, September 4, 2015 2:19 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by Eoin O'Callaghan
Indeed, the one I was working on is IC22! NOT 18, sorry!
On Friday, September 4, 2015 3:02 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
It looks like IC18 on the 366B is a TL072 (8-pin chip) in the tuning
circuit. He was definitely talking about the 367 board, where IC18 is the 14051
demultiplexer for the filter and envelope control voltages. Pin 11 is one of the
address lines that control it. Neither of them seem to be the kind of thing that
would cause the type of noise you are hearing. Can you upload a picture of the
top of the board, showing the chip you are working on?
Don B.
Sent: Friday, September 4, 2015 9:32 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks, well IC18 on the 367 board is fine
on pin 11 and the others, however IC18 on 366 is not fine. In fact a bunch of
previous re-tracing has been done on it and currently pin 11 is not showing
continuity. I dunno if you meant me to check IC18 on the 366 board?
On Friday, September 4, 2015 2:19 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by Malte Rogacki
Let's do this step by step.
1. Is the noise getting louder and quiter when moving the attenuator?
2. Is the noise getting louder and quiter when moving the keyboard away
from the boards?
2015-09-04 by <backshall1@bellsouth.net>
Oh, that’s the 368, not 366. It’s the chorus board.
Sent: Friday, September 4, 2015 10:07 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Ive put it together again and
its exactly the same. 367 chip 18 is fine. The chip I was working on is the one
right beside the battery except on the next board (366). Its a HD14069UBP
On Friday, September 4, 2015 3:02 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
It looks like IC18 on the 366B is a TL072 (8-pin chip) in the tuning
circuit. He was definitely talking about the 367 board, where IC18 is the 14051
demultiplexer for the filter and envelope control voltages. Pin 11 is one of the
address lines that control it. Neither of them seem to be the kind of thing that
would cause the type of noise you are hearing. Can you upload a picture of the
top of the board, showing the chip you are working on?
Don B.
Sent: Friday, September 4, 2015 9:32 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks, well IC18 on the 367
board is fine on pin 11 and the others, however IC18 on 366 is not fine. In fact
a bunch of previous re-tracing has been done on it and currently pin 11 is not
showing continuity. I dunno if you meant me to check IC18 on the 366
board?
On Friday, September 4, 2015 2:19 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by <backshall1@bellsouth.net>
And that’s IC 22 not 18. While you are in there, check for damage around
the CN03 connector. Check for around 10K ohms between the pins on the
connector.
Don B.
Sent: Friday, September 4, 2015 10:18 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Oh, that’s the 368, not 366. It’s the chorus board.
Sent: Friday, September 4, 2015 10:07 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Ive put it together again and
its exactly the same. 367 chip 18 is fine. The chip I was working on is the one
right beside the battery except on the next board (366). Its a HD14069UBP
On Friday, September 4, 2015 3:02 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
It looks like IC18 on the 366B is a TL072 (8-pin chip) in the tuning
circuit. He was definitely talking about the 367 board, where IC18 is the 14051
demultiplexer for the filter and envelope control voltages. Pin 11 is one of the
address lines that control it. Neither of them seem to be the kind of thing that
would cause the type of noise you are hearing. Can you upload a picture of the
top of the board, showing the chip you are working on?
Don B.
Sent: Friday, September 4, 2015 9:32 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks, well IC18 on the 367
board is fine on pin 11 and the others, however IC18 on 366 is not fine. In fact
a bunch of previous re-tracing has been done on it and currently pin 11 is not
showing continuity. I dunno if you meant me to check IC18 on the 366
board?
On Friday, September 4, 2015 2:19 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by Eoin O'Callaghan
OK, so from scratch...
Attenuator does indeed make it get louder and softer
Moving the keybed away from the boards does indeed make it get a bit quieter. Its still there but it is noticeably louder when back in its position beside the boards.
On Friday, September 4, 2015 3:22 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
And that’s IC 22 not 18. While you are in there, check for damage around
the CN03 connector. Check for around 10K ohms between the pins on the
connector.
Don B.
Sent: Friday, September 4, 2015 10:18 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Oh, that’s the 368, not 366. It’s the chorus board.
Sent: Friday, September 4, 2015 10:07 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Ive put it together again and
its exactly the same. 367 chip 18 is fine. The chip I was working on is the one
right beside the battery except on the next board (366). Its a HD14069UBP
On Friday, September 4, 2015 3:02 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
It looks like IC18 on the 366B is a TL072 (8-pin chip) in the tuning
circuit. He was definitely talking about the 367 board, where IC18 is the 14051
demultiplexer for the filter and envelope control voltages. Pin 11 is one of the
address lines that control it. Neither of them seem to be the kind of thing that
would cause the type of noise you are hearing. Can you upload a picture of the
top of the board, showing the chip you are working on?
Don B.
Sent: Friday, September 4, 2015 9:32 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Thanks, well IC18 on the 367
board is fine on pin 11 and the others, however IC18 on 366 is not fine. In fact
a bunch of previous re-tracing has been done on it and currently pin 11 is not
showing continuity. I dunno if you meant me to check IC18 on the 366
board?
On Friday, September 4, 2015 2:19 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
Sorry, the KLM-367 (the programmer board) is commonly called the “digital”
board since it has the A/D circuit, memory and D/A chip and the KLM-366 is the
“analog” board, since it has the oscillators and filters. They both have CPU
chips and quite a bit of digital circuits, so using those names can be
confusing. Sometimes the 366 is called the voice board, but I think the official
name is the key assigner board.
Don B.
Sent: Friday, September 4, 2015 8:54 AM
Subject: Re: [PolySix] Re: Noisy Polysix
2015-09-04 by cliofreak@yahoo.com
CN03 has many different reading between the 7 different pins. I tried a few and got different results. Some gave 0k and a couple read around 20k. Between pins 1 and 2 read 0.7M
2015-09-04 by cliofreak@yahoo.com
New video -
Noisy p6 Noisy p6 This feature is not available right now. Please try again later.
Preview by Yahoo
2015-09-04 by Malte Rogacki
Wait a second: What's that modification?
Is that a MIDI interface?
2015-09-04 by <backshall1@bellsouth.net>
And why are the black and white keyboard wires still lying on top of the
circuit board? Those are the ones that need to be kept away.
Sent: Friday, September 4, 2015 11:17 AM
Subject: [PolySix] Re: Noisy Polysix
Wait a second: What's that modification?
Is that a MIDI
interface?
2015-09-04 by Eoin O'Callaghan
Yeah its a MIDI mod and it works fine. Ill move the black and white wires now and see if it changes anything...
On Friday, September 4, 2015 4:50 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
And why are the black and white keyboard wires still lying on top of the
circuit board? Those are the ones that need to be kept away.
Sent: Friday, September 4, 2015 11:17 AM
Subject: [PolySix] Re: Noisy Polysix
Wait a second: What's that modification?
Is that a MIDI
interface?
2015-09-04 by synthmans@gmail.com
Yikes! A bit of a mess with the rewiring and the damaged tracks as a whole... likely you could have a number of vias/pads/tracks and such that need further scrutiny - not to mention those under chips...
One fellow I know contracted an 'assembler' to clean up and rewire his board... might be the most practical option if you don't feel you have the technical/hands-on skills.
Old Crow talks about removing those damaged traces since they're infused with the battery substance and can continue to decay/leach into good areas. From IMG_2913, the area I was mentioning is the 4051 stamped IC's, likely nested in the area of the ceramic capacitors standing closer to halfway across the board - opposite the battery. Your board could be an earlier rev so just look for the one with the stamped part number 4051 - should be two of them.
Otherwise, if the board is still in the original condition you really need to remove those damaged sections and replace with suitably sized wires... for fine stuff use wire wrap wire.
The induction of noise from stray wires is also a relevant issue....
2015-09-04 by cliofreak@yahoo.com
OK, a breakthrough of sorts...I thing this is a ground loop or something. When I touch the metal bracket for the keyboard onto the grounding plate that covers about 75% of the bass of the synth, the noise significantly returns. When I left it off the noise subsides to a significant extent. Still doesn't go away but nowhere near as loud. Any thoughts based on this discovery? The silver floor surface appears to be showing continuity with ground and seems to be getting this ground from the MIDI ports rivited to the body.
2015-09-04 by Malte Rogacki
If I'm reading the schematic right analog ground and digital ground are
tied together at the power supply (and only there!).
Another wild guess: The MIDI retrofit ties the grounds together at a
different point as well, hence a digital ground loop.
The silver backing at the bottom is normally tied to the backplane with a
single black cable that runs roughly from the location of the pink
connector on KLM368 to the socket ground on the backplane. If I'm not
mistaken this is digital ground since both the regular output and the
phones output are isolated sockets with a different ground.
For me right now the question is if the MIDI retrofit gets its power from
+5V and digital ground or +5V and analog ground. This could (!) have
something to do with the problem - but it also could be something
completely different.
Bottom line here is that the MIDI interface definitely adds another
possible culprit.
2015-09-04 by synthmans@gmail.com
Good point, you've got extra circuitry there that could be injecting noise into the analog section. The midi interface ground wire connection should have been made back at the power supply.
One telltale sign if the interface is at fault, is if it's a midi input and you exercise it via an external controller (slider etc.) you will hear a related 'zipper/buzz' effect as you exercise the control and send related midi controller data into the Polysix.
2015-09-05 by Eoin O'Callaghan
Ive used the MIDI retrofit with a DAW as a controller and the MIDI all works fine but the noise doesn't change. Its still the same as using it via just the jack.
2015-09-05 by synthmans@gmail.com
touching up that ground trace is not enough... you have to strip off the soldermask back to the good shiny copper, remove the bad section and add something like a copper braid to replace the cutoff bits... that ground is vital to preventing noise and minimizing glitches...
At the very least, polish up the bad areas of that ground strip and tin the entire length with a solid run of copper... use a piece of stripped stranded wire as your base to cross the bad part.
As far as the mess of orange wires on the back - they need to be redone as there's all sorts of 'gunk' left there - needs to be cleaned with alcohol and the replacement wiring should be done more cleanly, following the tracks as best you can and not running wires too close - certainly use the right size wires, not oversized ones.... otherwise, this is a poster version of how not to do it (to be honest)
Again, check those continuities, don't be surprised if you fine a bad one or two in spite of getting sound out of the synth...
2015-09-05 by Eoin O'Callaghan
To be honest, i did go over the whole ground strip with a fiberglass pen, removing as much black as possible and leaving only the parts that look fine with the mask. The sole touch up seemed a bit pointless when I was doing it. Kinda like random bits of solder on top of perfectly good copper. I also came across difficulty getting the board back into the metal 'board holder thing' under the keys as it was too thick with the extra solder on the ground strip.
2015-09-05 by synthmans@gmail.com
The area in question was the ground strip adjacent to the battery... everywhere else should be fine as is - you only want to work on affected/suspect areas...if you've left too much solder on the other areas, remove it with copper braid solder wick (it should have been applied as a smooth thin application, using the solder iron along the strip),
All the suggestions I've seen are good sound ones, but it only takes one minor fault to glitch the system...
BTW, hopefully not chasing our tails, but there should be a ground wire from the back panel to the metal sheet under the boards - that lug should be secure, not loose, to ensure a good grounding of that noise shield
2015-09-05 by synthmans@gmail.com
Also, you can't leave bare exposed copper, you have to tin it....
2015-09-05 by synthmans@gmail.com
Did you carry out the instruction in Old Crow's Polysix repair website? It says to carefully break the glue (loctite) securing the connectors (see his post) and to pop them apart without undue stress to the assy. Thereafter, inspect for any tarnish and reseat them to ensure a positive contact is made...
For each connector, after carefully cutting through the glue, start to work the upper connector+cable assembly out of the corresponding socket. These things can be stubborn, so watch the amount of force applied. Do NOT wiggle the connectors from side to side, this weakens the pins soldered to the KLM-367. If one or more connectors are being troublesome, grasp the connector shell at either end and try to "rock" the connector up and out along the connector's length. If you can fit the tip of a small, flat-tip screwdriver between the socket and connector along the open edge, it will help. Most connectors will give a final 'crack' as the glue that managed to get inside breaks, at which point the connector easily pops out.
2015-09-05 by Eoin O'Callaghan
Hey, yeah I had no difficulty getting them out. I broke the glue before doing it a few days ago. Don't think there is an issue there. Ive been speaking to the guy who owned and 'rebuilt' it before me. He said -
the noise result by lifting the keyboard seems to be the result of a grounding problem. so there must be an interruption of the grounding all over the synth. not funny indeed. i would check the result by removing the MIDI board. you can connect the keyboard also the original way - no cables are modified as i remember. So check this first. maybe it is injected by the MIDI board - only a suggestion of mine.
2015-09-05 by cliofreak@yahoo.com
So, Im trying to remove the MIDI setup to see if its causing the issue. Anyone know how the stock P6 should look. Ribbon cable etc?
2015-09-05 by <backshall1@bellsouth.net>
That sounds like a lot of work. “no cables are modified”? To put it back
the way it was, you would need to unsolder all the black and white wires from
the midi board and solder them in the correct order to the key contact circuit
board on the bottom of the keyboard, which also means unsoldering all of the
red/black or orange/black (colors are hard to tell in the video) that are
currently soldered to the key contact board. How about unscrewing the midi board
and lifting it up to isolate it from the foil shield below? Does that make any
difference? The way it makes more noise when the metal keybed touches the foil
shield could be a ground loop or it could mean something is connected to the
foil that shouldn’t be, so it is acting more as an antenna for noise. There
should be no connection between any of the red/black wires and the metal keybed.
The only connection to the metal keybed should be when it touches the foil
shield. The only ground connection to the foil shield should be one wire from a
lug screwed into the foil just behind the chorus board which is soldered to the
ground of the output jack on the jack panel. Also you have that gray ribbon
cable running over to something on the 366B board which looks like another
non-factory circuit board wrapped in some sort of white foam. Is it screwed
down? Can you lift it away from other components to see if the noise
changes?
Don B.
Sent: Saturday, September 5, 2015 8:01 AM
Subject: Re: [PolySix] Re: Noisy Polysix
Hey, yeah I had no difficulty
getting them out. I broke the glue before doing it a few days ago. Don't think
there is an issue there. Ive been speaking to the guy who owned and 'rebuilt' it
before me. He said -
the
noise result by lifting the keyboard seems to be the result of a grounding
problem. so there must be an interruption of the grounding all over the synth.
not funny indeed. i would check the result by removing the MIDI board. you can
connect the keyboard also the original way - no cables are modified as i
remember. So check this first. maybe it is injected by the MIDI board - only a
suggestion of mine.
2015-09-05 by synthmans@gmail.com
See if you can trace back the grounding, to ensure there's no loops/shorts etc. The Midi wires should not be put in the same run as the analog wires... that's one way that crosstalk can occur, straight electromagnetic induction. The midi wires should ideally be in a shielded cable and a short run, not stretching across the works, again acting as a big antenna. Also the keyscanning wires off the MIDI assy should be in a shielded cable - as for the board sitting smack in on top of the analog section.... 'there's your sign' ; )
The newer midi addons are certainly a lot smaller! If you want to upgrade, t
here's enough people that would probably pay enough for the old midi interface so sell that old clunker i/f on Ebay and put that towards a newer cleaner one, for example: CHD ELEKTROSERVISCHD ELEKTROSERVISMIDI DMX DCB CV TR808 TR-808 CR78 CR-78 JUNO60 JUNO-60 JUPITER4 JUPITER-4
Preview by Yahoo
At the very least, seperate out the midi connector wiring - remove them temporarily and get them away from the rest of the circuits (without shorting anything to the related parts), temporarily elevate the midi board away from the board and see if that helps.... worst comes to worse, you can install a metal shield between it and the board beneath, but you have to ground it back to the supply and make sure it doesn't short out anywhere... some of those chips can get warm, you certainly don't want a chunk of styrofoam there either, firstly as it's a static generator that can zap your chips in the right circumstances (more a theoretical, but still possible) and it will cause heat build up of the 'insulated parts'... premature failure if it's bad enough.
2015-09-05 by synthmans@gmail.com
Curious what model that midi interface is... definitely Old School.
Here's an example of a clean rewiring... a world of difference
2015-09-05 by synthmans@gmail.com
That interface is purely for triggering the keyboard lines and doesn't offer any advantages, other than possibly for variations on Arpeggiator and whatever else can be done by automating the keys, otherwise may not do anything but act as a straight keyboard trigger.... I'm curious so will see what the board markings show - definitely not a Kenton. ; )
2015-09-05 by synthmans@gmail.com
Here's the company that made your interface... EES in Germany, you might be able to get info from them via email (assuming you don't already have the documentation).... definitely would help in terms of selling it and upgrading to the CHD device... ; )
About EES About EES EES EES (= electronics, development, service) was set up by Dipl. Ing. Thomas Wieschiolek in Mölln in 1983.
Preview by Yahoo
2015-09-05 by synthmans@gmail.com
Well I guess you'd be lucky to track down any related info....
After more than 25 years successful experience we finish
December 31, 2008 our business.
With our customers and business partners
We would like to take this opportunity to thank for
their loyalty, which they have placed us
Trust and pleasant cooperation.
Our website still remains to also
continue downloading
EES -Bedienungsanleitungen and drivers
to allow.
Potentially occurring warranty cases
please take the following e-mail address
Contact us: info@ees-musik.de
Mölln, in December 2008
2015-09-05 by Eoin O'Callaghan
haha, well thats no good!
2015-09-05 by synthmans@gmail.com
Hey, don't knock it... that interface is still useful and you can bet others would be willing to go for it on Ebay, as long as you document (photograph) it's installation and carefully remove, put in an antistatic bag (chuck that foam!) - it's a very simple device really that most anybody can figure out... just state it's an older/working interface that you don't need anymore. ; )
2015-09-05 by <backshall1@bellsouth.net>
You’re still talking about unsoldering at least 32 wires and resoldering
the black and white ones back to their correct location, then trying to explain
to someone else exactly how to reconnect 32 wires on their keyboard. Sounds like
it would need careful documentation if you want to try a different midi kit and
sell that one to someone else. How about getting those two circuit boards and
associated wiring lifted up away from the KLM boards? Any progress there?
Don B.
Sent: Saturday, September 5, 2015 11:15 AM
Subject: [PolySix] Re: Noisy Polysix
Hey, don't knock it... that interface is still useful and you can bet others
would be willing to go for it on Ebay, as long as you document (photograph) it's
installation and carefully remove, put in an antistatic bag (chuck that foam!) -
it's a very simple device really that most anybody can figure out... just state
it's an older/working interface that you don't need anymore. ; )
2015-09-05 by Eoin O'Callaghan
Hey, yeah I lifted them off and had loads of separation. Moved the wires off the boards...moved the midi wires from any where near the analog board or wires...checked the ground as much a I could and can't see anything un usual. Its all still exactly the same. The ground hum comes an goes with the key bed being lied in and out but even when its a bit quieter there is still the crazy circus frequencies whistling away as you play...only when filter is rolled off so you can hear them. Wide open its so fuzzy and loud that it drowns them out.
On Saturday, September 5, 2015 4:51 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
You’re still talking about unsoldering at least 32 wires and resoldering
the black and white ones back to their correct location, then trying to explain
to someone else exactly how to reconnect 32 wires on their keyboard. Sounds like
it would need careful documentation if you want to try a different midi kit and
sell that one to someone else. How about getting those two circuit boards and
associated wiring lifted up away from the KLM boards? Any progress there?
Don B.
Sent: Saturday, September 5, 2015 11:15 AM
Subject: [PolySix] Re: Noisy Polysix
Hey, don't knock it... that interface is still useful and you can bet others
would be willing to go for it on Ebay, as long as you document (photograph) it's
installation and carefully remove, put in an antistatic bag (chuck that foam!) -
it's a very simple device really that most anybody can figure out... just state
it's an older/working interface that you don't need anymore. ; )
2015-09-05 by synthmans@gmail.com
True of course, but I can send a photo of my keyboard wiring for reference... as far as the interface, spread out the wiring and take some definitive photographs that a prospective buyer would be able to follow.... I'm sure there's people out there that would be happy enough with this dated one...
2015-09-05 by Eoin O'Callaghan
Trouble is, Im happy with the MIDI. Ive been tracking with it all morning and it works well. I just want to be able to create soft pads as well as loud fuzz. I don't know if changing the MIDI to KIWI will solve that issue.
2015-09-05 by <backshall1@bellsouth.net>
How about unscrewing the wire that is attached to the foil behind the
chorus board? If the problem is too many grounds, maybe getting rid of one would
help.
Sent: Saturday, September 5, 2015 12:03 PM
Subject: Re: [PolySix] Re: Noisy Polysix
Hey, yeah I lifted them off and had loads of
separation. Moved the wires off the boards...moved the midi wires from any where
near the analog board or wires...checked the ground as much a I could and can't
see anything un usual. Its all still exactly the same. The ground hum comes an
goes with the key bed being lied in and out but even when its a bit quieter
there is still the crazy circus frequencies whistling away as you play...only
when filter is rolled off so you can hear them. Wide open its so fuzzy and loud
that it drowns them out.
On Saturday, September 5, 2015 4:51 PM,
"backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com>
wrote:
You’re still talking about unsoldering at least 32 wires and resoldering
the black and white ones back to their correct location, then trying to explain
to someone else exactly how to reconnect 32 wires on their keyboard. Sounds like
it would need careful documentation if you want to try a different midi kit and
sell that one to someone else. How about getting those two circuit boards and
associated wiring lifted up away from the KLM boards? Any progress there?
Don B.
Sent: Saturday, September 5, 2015 11:15 AM
Subject: [PolySix] Re: Noisy Polysix
Hey, don't knock it... that interface is still useful and you can bet
others would be willing to go for it on Ebay, as long as you document
(photograph) it's installation and carefully remove, put in an antistatic bag
(chuck that foam!) - it's a very simple device really that most anybody can
figure out... just state it's an older/working interface that you don't need
anymore. ; )
2015-09-05 by synthmans@gmail.com
Leaving the foil floating would turn it into a big antenna - radiating/coupling noise throughout the area, to every board... you have to review every wired ground connection and make sure they're typically made back to a common point at the power supply (star topology) so they don't pick up each others noisy currents.
There is that 'june production fix' I've seen on Old Crows's...
As far as keeping that midi interface:
a) it's messy, and a hazard to deal with
b) it's power hungry and loading the supply meant only to power the original circuitry - could lead easily to premature failure due to additional load/heating stress (something the folks at KIWI mention as a reason to replace with their modern upgrade - though incredibly expensive!)
c) it covers up and blocks access to way too much circuitry...
d) a new assembly from CHD would keep thing compact and minimize any related headaches of wires / grounds and all the rest
e) A new interface would increase the value of your synth - no if's, ands or buts.....
No doubt there's still work to be done to get rid of those 'gremlin' noises...again, you seriously have to clean things up first before you can deal with that in a reasonably effective manner... just common sense really.
That jumpering was poorly done... also if there's even the slightest bit of battery residue on the board (in the wrong place), it's highly conductive and will connect signals that should otherwise be isolated - the exact symptom I dealt with to fix a fellow's P6.
You can't clean what you can't get at, buried under a mass of poorly installed jumper wires or being blocked by an oversized, oldschool sized interface from the previous century....
These points are rather straight forward, but if you have any doubts about doing it properly, hire a tech or even an assembler... well worth the investment and again increases the serious value of the synth for when you decide to part ways.
Otherwise, poking around forever and a day, however 'entertainingly productive' it may seem and you might still get lucky and find the issue, otherwise just drags out the inevitable....
2015-09-05 by <backshall1@bellsouth.net>
The foil is already either acting like an antenna or creating a ground
loop. Since the “real” ground is connected, it is probably a ground loop, so
eliminating that one ground could cause a significant difference. Either way, it
can provide some clue to what is going on if it makes a difference.
Sent: Saturday, September 5, 2015 1:02 PM
Subject: Re: [PolySix] Re: Noisy Polysix
Leaving the foil floating would turn it into a big antenna -
radiating/coupling noise throughout the area, to every board... you have to
review every wired ground connection and make sure they're typically made back
to a common point at the power supply (star topology) so they don't pick up each
others noisy currents.
There is that 'june production fix' I've seen on Old Crows's...
As far as keeping that midi interface:
a) it's messy, and a hazard to deal with
b) it's power hungry and loading the
supply meant only to power the original circuitry - could lead easily to
premature failure due to additional load/heating stress (something the folks at
KIWI mention as a reason to replace with their modern upgrade - though
incredibly expensive!)
c) it covers up and blocks access
to way too much circuitry...
d) a new assembly from CHD would keep
thing compact and minimize any related headaches of wires / grounds and all the
rest
e) A new interface would increase the
value of your synth - no if's, ands or buts.....
No doubt there's still work to be done
to get rid of those 'gremlin' noises...again, you seriously have to clean things
up first before you can deal with that in a reasonably effective manner... just
common sense really.
That jumpering was poorly done... also
if there's even the slightest
bit of battery residue on the board (in the wrong place), it's highly conductive and will connect
signals that should otherwise be isolated - the exact symptom I dealt with to
fix a fellow's P6.
You can't clean what you can't get at,
buried under a mass of poorly installed jumper wires or being blocked by an
oversized, oldschool sized interface from the previous century....
These points are rather straight forward, but if you have any doubts about
doing it properly, hire a tech or even
an assembler... well worth the investment and again increases the
serious value of the synth for when you decide to part ways.
Otherwise, poking around forever and a day, however 'entertainingly
productive' it may seem and you might still get lucky and find the issue,
otherwise just drags out the inevitable....
2015-09-05 by <backshall1@bellsouth.net>
By the way, what is that extra button above the pitch wheel for?
Sent: Saturday, September 5, 2015 2:20 PM
Subject: Re: [PolySix] Re: Noisy Polysix
The foil is already either acting like an antenna or creating a ground
loop. Since the “real” ground is connected, it is probably a ground loop, so
eliminating that one ground could cause a significant difference. Either way, it
can provide some clue to what is going on if it makes a difference.
Sent: Saturday, September 5, 2015 1:02 PM
Subject: Re: [PolySix] Re: Noisy Polysix
Leaving the foil floating would turn it into a big antenna -
radiating/coupling noise throughout the area, to every board... you have to
review every wired ground connection and make sure they're typically made back
to a common point at the power supply (star topology) so they don't pick up each
others noisy currents.
There is that 'june production fix' I've seen on Old Crows's...
As far as keeping that midi interface:
a) it's messy, and a hazard to deal with
b) it's power hungry and loading the
supply meant only to power the original circuitry - could lead easily to
premature failure due to additional load/heating stress (something the folks at
KIWI mention as a reason to replace with their modern upgrade - though
incredibly expensive!)
c) it covers up and blocks access
to way too much circuitry...
d) a new assembly from CHD would keep
thing compact and minimize any related headaches of wires / grounds and all the
rest
e) A new interface would increase the
value of your synth - no if's, ands or buts.....
No doubt there's still work to be done
to get rid of those 'gremlin' noises...again, you seriously have to clean things
up first before you can deal with that in a reasonably effective manner... just
common sense really.
That jumpering was poorly done... also
if there's even the slightest
bit of battery residue on the board (in the wrong place), it's highly conductive and will connect
signals that should otherwise be isolated - the exact symptom I dealt with to
fix a fellow's P6.
You can't clean what you can't get at,
buried under a mass of poorly installed jumper wires or being blocked by an
oversized, oldschool sized interface from the previous century....
These points are rather straight forward, but if you have any doubts about
doing it properly, hire a tech or even
an assembler... well worth the investment and again increases the
serious value of the synth for when you decide to part ways.
Otherwise, poking around forever and a day, however 'entertainingly
productive' it may seem and you might still get lucky and find the issue,
otherwise just drags out the inevitable....
2015-09-05 by Eoin O'Callaghan
It seems to mute all
On Saturday, September 5, 2015 7:22 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
By the way, what is that extra button above the pitch wheel for?
Sent: Saturday, September 5, 2015 2:20 PM
Subject: Re: [PolySix] Re: Noisy Polysix
The foil is already either acting like an antenna or creating a ground
loop. Since the “real” ground is connected, it is probably a ground loop, so
eliminating that one ground could cause a significant difference. Either way, it
can provide some clue to what is going on if it makes a difference.
Sent: Saturday, September 5, 2015 1:02 PM
Subject: Re: [PolySix] Re: Noisy Polysix
Leaving the foil floating would turn it into a big antenna -
radiating/coupling noise throughout the area, to every board... you have to
review every wired ground connection and make sure they're typically made back
to a common point at the power supply (star topology) so they don't pick up each
others noisy currents.
There is that 'june production fix' I've seen on Old Crows's...
As far as keeping that midi interface:
a) it's messy, and a hazard to deal with
b) it's power hungry and loading the
supply meant only to power the original circuitry - could lead easily to
premature failure due to additional load/heating stress (something the folks at
KIWI mention as a reason to replace with their modern upgrade - though
incredibly expensive!)
c) it covers up and blocks access
to way too much circuitry...
d) a new assembly from CHD would keep
thing compact and minimize any related headaches of wires / grounds and all the
rest
e) A new interface would increase the
value of your synth - no if's, ands or buts.....
No doubt there's still work to be done
to get rid of those 'gremlin' noises...again, you seriously have to clean things
up first before you can deal with that in a reasonably effective manner... just
common sense really.
That jumpering was poorly done... also
if there's even the slightest
bit of battery residue on the board (in the wrong place), it's highly conductive and will connect
signals that should otherwise be isolated - the exact symptom I dealt with to
fix a fellow's P6.
You can't clean what you can't get at,
buried under a mass of poorly installed jumper wires or being blocked by an
oversized, oldschool sized interface from the previous century....
These points are rather straight forward, but if you have any doubts about
doing it properly, hire a tech or even
an assembler... well worth the investment and again increases the
serious value of the synth for when you decide to part ways.
Otherwise, poking around forever and a day, however 'entertainingly
productive' it may seem and you might still get lucky and find the issue,
otherwise just drags out the inevitable....
2015-09-05 by florian anwander
Am 05.09.2015 um 20:24 schrieb Eoin O'Callaghan
cliofreak@yahoo.com
[PolySix]:
> It seems to mute all
>> By the way, what is that extra button above the pitch wheel for?
If I remember the EES-Interface right, it was for the selection of the
MIDI-Channel (I think: press the button and select the channel with the
lowest 16 keys). And please don't ask further questions: I worked with a
composer in the late 80ies, who had a Polysix with the EES interface.
That is my only experience with this device. Both - composer and synth -
are no longer available :-/.
Florian
2015-09-05 by synthmans@gmail.com
Seems they did quite a bit in their day with Midi interfaces etc. Apparently making the Unitor and AMT for Emagic... otherwise, very specific to the European market and no info on the Polysix Midi interface to be found.
I see related interfaces, albeit a bit more modern, offered for the Poly61 - they go for about 70USD...
2015-09-05 by synthmans@gmail.com
Ground issues can be confusing, I figured the basic theory would be worth mentioning - again, more for the uninitiated... sometimes those ground lugs are also for common ground power distribution via the chassis.
Also worth mentioning... the P6 uses a grounded plug, which occasionally can be an issue when connecting it to external devices with grounds or leaky AC, like mixers, computer interfaces (USB midi on the korg SQ1) and such, which result in odd noises ... but I think that was covered by reverting back to the headphones being the only device plugged into the P6?
**************
The foil is already either acting like an antenna or creating a ground loop. Since the “real” ground is connected, it is probably a ground loop, so eliminating that one ground could cause a significant difference. Either way, it can provide some clue to what is going on if it makes a difference.
2015-09-05 by synthmans@gmail.com
The EES midi interface seems to have been a generic platform, perhaps with a bit of code customization for the related synth/organ etc. Otherwise, it's also here on this Oberheim OBX... I'll ask Sneak-Thief if he knows anything of it as he's very much hardware/software savvy...
2015-09-05 by <backshall1@bellsouth.net>
Are those the midi jacks way over on the right hand wood panel at the end
of the yellow wires? Considering they should be as close as possible and
preferably use shielded cable, those look like they are as far away as possible
and not shielded, although the tight twist in the wire does a decent job of
cancelling out any noise picked up.
Back to the Polysix we are looking at, I have some questions about where
they are getting power from. Both boards need power. I can see a pair of
red/black or orange/black wires coming off the board that was wrapped in foam,
but I can’t see what the other end of these wires is connected to and it looks
like the wires may be looped around in a messy coil. Not good. I assume the
other board gets powered over the ribbon cable.
Sent: Saturday, September 5, 2015 5:09 PM
Subject: [PolySix] Re: Noisy Polysix
The EES midi interface seems to have been a generic platform, perhaps with a
bit of code customization for the related synth/organ etc.
Otherwise, it's also here on this Oberheim OBX... I'll ask Sneak-Thief if he
knows anything of it as he's very much hardware/software savvy...
2015-09-05 by synthmans@gmail.com
Yep, those are the midi jacks - as far as I read, this was EES's generic oem style product and ended up in a number of synth's and organs, with a bit of custom code where needed.
I think the twisted pair is (mostly) for cancellation of Common Mode interference picked up by the cable, otherwise, don't you need a properly terminated shield to block emission from the wires? EMI is tricky as you have to have your shields and drains connected to ensure effectiveness....sometimes at one end only, other times at both etc. All depends on the related bits being interconnected...
2015-09-05 by Eoin O'Callaghan
The MIDI board is getting power from the top left of the back power board...as seen here. I haven't unravelled the red/black wires yet because its up stairs and I'm having a beer ;)
On Saturday, September 5, 2015 10:40 PM, "backshall1@bellsouth.net [PolySix]" <PolySix@yahoogroups.com> wrote:
Are those the midi jacks way over on the right hand wood panel at the end
of the yellow wires? Considering they should be as close as possible and
preferably use shielded cable, those look like they are as far away as possible
and not shielded, although the tight twist in the wire does a decent job of
cancelling out any noise picked up.
Back to the Polysix we are looking at, I have some questions about where
they are getting power from. Both boards need power. I can see a pair of
red/black or orange/black wires coming off the board that was wrapped in foam,
but I can’t see what the other end of these wires is connected to and it looks
like the wires may be looped around in a messy coil. Not good. I assume the
other board gets powered over the ribbon cable.
Sent: Saturday, September 5, 2015 5:09 PM
Subject: [PolySix] Re: Noisy Polysix
The EES midi interface seems to have been a generic platform, perhaps with a
bit of code customization for the related synth/organ etc.
Otherwise, it's also here on this Oberheim OBX... I'll ask Sneak-Thief if he
knows anything of it as he's very much hardware/software savvy...
2015-09-06 by Florian Anwander
On 05.09.15 23:40 , backshall1@bellsouth.net [PolySix] wrote:
Are those the midi jacks way over on the right hand
wood panel at the end of the yellow wires? Considering
they should be as close as possible and preferably use
shielded cable, those look like they are as far away
as possible and not shielded, although the tight twist
in the wire does a decent job of cancelling out any
noise picked up.
I doubt that this noise is induced by interference. It is clearly a
single signal with increasing frequency counting up to 8 variation
directly related to the keyboard.
I think we should focus on finding the place where this kind of
signal is generated. It must be a chip, which is addressed by three
bits (or more more bits, where three of them are shared with the
keyboard matrix) and it must be a chip that generates a frequency
(clock, reset signal, ... ) depending on this address.
Florian
2015-09-06 by Eoin O'Callaghan
I agree. This seems to be a more complex sound than interference. Id say there is a ground issue somewhere in there and is seen in action when keyboard is lifted in and out BUT I d say you're right...there is something else at play here.
2015-09-06 by Eoin O'Callaghan
Not sure if this helps but the noise is connected to whatever is going on in MG. By that I mean, it affects it, not causes it.
P6
2015-09-06 by florian anwander
We should check the signalpath with an scope, where this unwanted signal
can be located the earliest, and then the control voltages.
Check with an: VCO Out, VCF Out (change the cutoff while checking), VCA
Out (turn cutoff down while checking), Chorusboard out (with cutoff down).
Then check the control voltages:
VCO Pitch and Modulation CV
VCF Cutoff at pin 13 of 2044
VCA at R133
My personal suspect is now a multiplexer for a CV or the gate latches.
Florian
Am 06.09.2015 um 10:48 schrieb Eoin O'Callaghan
cliofreak@yahoo.com
[PolySix]:
> I agree. This seems to be a more complex sound than interference. Id say
> there is a ground issue somewhere in there and is seen in action when
> keyboard is lifted in and out BUT I d say you're right...there is
> something else at play here.
>
>
2015-09-07 by synthmans@gmail.com
I'm definitely going to check out Bob's Midi Interface for a bunch of synths - same sort of basic functionality, but in a much more compact and cleaner... ; )
