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Discussion about the Korg PolySix synthesizer

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The Post I didn't want to make....

The Post I didn't want to make....

2016-02-07 by jw_dewdney@yahoo.com

Well I got the Jorgensen KLM 367 transplanted back into the P6 and thought I'd try to take it on a test run. I even went so far as to get all the VR pots back into the ballpark (compared to measured values from the old board)... I've been SO unbelievably cautious with this build (even did every solder joint under a stereo microscope) - I was kind of half hoping it would work straight out of the gate.

But NO.

what came through the headphone jack sounded healthy at least (the usual P6 hash noise) - but EVERY LIGHT on the front panel was lit up and there was NOTHING I could do about it (no matter how much button pushing etc). Does ANYONE have any idea what the problem could be (wrong DC offset from VR5?) ... grounding problems? Has anyone ever experienced this before from a Jorgensen board build? (yeah I did correct for the bugs in the board etc) - and no - i'm not getting any audio on key depresses.

This particular P5 showed no such symptoms before putting the board in... just the usually flakey KLM367 problems...

thanks in advance


Re: [PolySix] Re: The Post I didn't want to make....

2016-02-07 by Bob Grieb

You should be able to go into Manual mode and see if the board is working.
Then you are using the front panel controls.

I replaced my KLM-367 with the new pcb.   It worked fine.   I think I used the 
standoffs from the old board, BTW.

Bob

--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Sunday, February 7, 2016, 3:38 AM
 
 
  
 
 
 
   
 
 
     
       
       
       or is this fairly normal behaviour before one has
 any patches loaded in perhaps....?
 
     
      
 
     
     
 
 
 
 #yiv9752142725 #yiv9752142725 --

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-07 by Bob Grieb

Check the reset input to the CPU, and the oscillator waveform.
Also, there is a test pt on the side of the CPU towards the effects bd
that I think should have a pulse on it every so often if the code is running
normally.   Of course check 5V at the logic chips.

Lots of other things to check with a scope if it's really not working.
The DAC output is one,   as it should be doing the succ approx on 
the pots over and over.

Bob

--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Sunday, February 7, 2016, 3:38 AM
 
 
  
 
 
 
   
 
 
     
       
       
       or is this fairly normal behaviour before one has
 any patches loaded in perhaps....?
 
     
      
 
     
     
 
 
 
 #yiv6311682205 #yiv6311682205 --

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-07 by <backshall1@bellsouth.net>

Did you use 22pF and 10pF for C23 and C22 near the 6 MHZ ceramic resonator? Many people have found that the new boards are very unstable with these values, and you need to use 10pF for both capacitors to get the clock running properly. I have also used both the original standoffs and the new ones. Just drill the hole out a bit bigger if they do not fit.
Don Backshall
Show quoted textHide quoted text
From: mailto:PolySix@yahoogroups.com 
Sent: Sunday, February 7, 2016 12:10 PM
To: PolySix@yahoogroups.com 
Subject: Re: [PolySix] Re: The Post I didn't want to make....

  
Check the reset input to the CPU, and the oscillator waveform.
Also, there is a test pt on the side of the CPU towards the effects bd
that I think should have a pulse on it every so often if the code is running
normally. Of course check 5V at the logic chips.

Lots of other things to check with a scope if it's really not working.
The DAC output is one, as it should be doing the succ approx on 
the pots over and over.

Bob

--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:

Subject: [PolySix] Re: The Post I didn't want to make....
To: PolySix@yahoogroups.com
Date: Sunday, February 7, 2016, 3:38 AM


 









or is this fairly normal behaviour before one has
any patches loaded in perhaps....?









#yiv6311682205 #yiv6311682205 --

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-07 by jw_dewdney@yahoo.com

thanks for the suggestions Bob! no... i used the 22pf cap on the materials list... i came across the post about the 10pf replacement just yesterday in fact. the one thats supposed to be 10pf measured closer to 3pf... though its pretty hard to get an accurate fix on values in the low pf range even with really good equipment as you know. i think ill order some 10pf caps and do some replacing on the board.

i asked if this was some kind of 'normal condition' because someone just below in a post who just did the same board swap just mentioned something cryptic about loading factory programs and how now 'more of the lights seem to be going away'... or something to that effect... perhaps i should ask him...!

also... is there a FAQ somewhere here on relevant problems? or something from Jed on 'startup procedures' and troubleshooting? im having a bit of a hard time getting relevant search results in this group. as for the reset pin on the processor... what kind of input does in need to start the interrupt? short to ground? guess i should read the manual for that processor...

i could also try swapping processors i guess (have two more p6s to do!... hope i can get one of em right!!). id have tried the board in one of the other p6s though it really looks as though the problem is coming from the new board...

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-07 by Bob Grieb

Hi,

   Let's not mix reset with interrupt, OK?  

   RESETb on the 8048 is an active low signal that puts the CPU in 
a known condition, ready to start executing code once the signal
is released.   It is a low level to reset the CPU, and high to let it run.
Pretty much all CPU's need a reset signal to put them into a known 
state at power up (although some generate the signal internally).
If you don't have a storage scope, it will be hard to see that reset is
low when you power up.   Mainly you are just checking to see that it's
high normally, to let the CPU run.

   In general, RESETb would be asserted for a long enough time to 
let the crystal oscillator start up, and the 5V power stabilize.    The oscillator
would only take a few mS to get going, typically, but reset is often asserted
for maybe 100-200 mSec, since all that does is make the start-up take a little
longer and you want to make sure the CPU is reset properly.

    Bob

--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: Re: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Sunday, February 7, 2016, 1:31 PM
     
       
       thanks for the suggestions Bob! no... i used the
 22pf cap on the materials list... i came across the post
 about the 10pf replacement just yesterday in fact. the one
 thats supposed to be 10pf measured closer to 3pf... though
 its pretty hard to get an accurate fix on values in the low
 pf range even with really good equipment as you know. i
 think ill order some 10pf caps and do some replacing on the
 board.
 i asked if this
 was some kind of 'normal condition' because someone
 just below in a post who just did the same board swap just
 mentioned something cryptic about loading factory programs
 and how now 'more of the lights seem to be going
 away'... or something to that effect... perhaps i should
 ask him...!
 also... is
 there a FAQ somewhere here on relevant problems? or
 something from Jed on 'startup procedures' and
 troubleshooting? im having a bit of a hard time getting
 relevant search results in this group. as for the reset pin
 on the processor... what kind of input does in need to start
 the interrupt? short to ground? guess i should read the
 manual for that processor...
 i could also try swapping processors
 i guess (have two more p6s to do!... hope i can get one of
 em right!!). id have tried the board in one of the other p6s
 though it really looks as though the problem is coming from
 the new board...
 
     
      
 
     
     
 
 
 
 #yiv0913980484 #yiv0913980484 --

Re: The Post I didn't want to make....

2016-02-07 by jw_dewdney@yahoo.com

Okay thanks sorry I was being a bit sloppy with my language i guess. But what sort of signal is the reset pin expecting to see? That's all i'm asking... should i try shorting it to ground? or... shorting it to the +5V supply, etc? or it needs some sort of binary signal? (i'm a bit out of my ken here)

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-07 by Bob Grieb

Do not short reset to ground, since there is an op amp 
output driving it.   You could damage that.    Just check it with a scope
(or a meter if you don't have that) to see that it is normally sitting high. (>3.5V)
I just looked at the code again, and the first thing the CPU does is to 
turn off all the program LEDs.  Then it checks the DAC calibration 
switch.  So if you put that switch in the calibrate position (on?  not sure)
then the CPU should jump to that code and most of the LEDs should be off.
If that doesn't work, then your CPU is not executing, which means you either 
are asserting or pulsing reset, or the oscillator is not working properly, as 
mentioned before.   I think I took the osc caps off of the old board as I didn't 
want to run into that issue.   

    Bob

--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Sunday, February 7, 2016, 3:20 PM
 
 
  
 
 
 
   
 
 
     
       
       
       Okay thanks sorry I was being a bit sloppy with my
 language i guess. But what sort of signal is the reset pin
 expecting to see? That's all i'm asking... should i
 try shorting it to ground? or... shorting it to the +5V
 supply, etc? or it needs some sort of binary signal?
 (i'm a bit out of my ken here)
 
     
      
 
     
     
 
 
 
 #yiv8195600559 #yiv8195600559 --

Re: The Post I didn't want to make....

2016-02-07 by jw_dewdney@yahoo.com

I just checked the test points on the 367 board. Looks like I'm only getting juice on TP4.... so I guess there are deeper issues to resolve. The power supply is working fine (known good and just verified at all voltages). Sorry I should have checked that first... before posting. My confidence was running a bit high. It looks also like someone did some work on the connector wiring previously (some splicing wtih electrical tape on them) - so I'll see if I'm getting the same problem on another polysix first before I delve into problems on the board. I also noticed the new lithium cell is at 0v now... so I wonder if I did cook that SRAM chip... well - could be anything of course.

Re: The Post I didn't want to make....

2016-02-08 by jw_dewdney@yahoo.com

but still... lighting everything up on the top of the polysix - no voices - and the bad voltages on the 367 board make me think something along the lines of ground fault somewhere on the board... any ideas or suggestions for a strategy to troubleshoot? I'm going through the schematic and trying to figure out what could do that... but no luck yet

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-08 by Bob Grieb

If the front panel board has power, the latches that control the LED's may simply come up 
in the state that would light the LED.   Normally the CPU would turn them off right away, 
but if it's not running, then they stay on.  So the KLM board is not turning them on.
It's just not turning them off.

You soldered the big gnd wire to the copper on the edge of the KLM-367, near the battery, right?

If you don't have good power on the KLM-367, use your ohmmeter to measure continuity 
between the power supply and the KLM-367 for each voltage and ground.  (with power off, of course)

Bob


--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Sunday, February 7, 2016, 8:01 PM
 

       but still... lighting everything up on the top of
 the polysix - no voices - and the bad voltages on the 367
 board make me think something along the lines of ground
 fault somewhere on the board... any ideas or suggestions for
 a strategy to troubleshoot? I'm going through the
 schematic and trying to figure out what could do that... but
 no luck yet
 
     
      
 
     
     
 
 
 
 #yiv8800374166 #yiv8800374166 --

Re: The Post I didn't want to make....

2016-02-08 by jw_dewdney@yahoo.com

okay thanks - yes that sure makes sense - and yes I even tried firing it up without the ground wire connected once (just to see) but no difference. But yeah that makes lots of sense... I wasn't sure to what degree the board power was being 'mediated' by the processor or any other devices - though I don't see why it would...

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-08 by Bob Grieb

Some products send around a higher voltage, like 9VDC or maybe 12VDC, and each board
has its own regulator to create 5V from the higher voltage.   But that's a more expensive 
approach.   And if the PolySix were doing that, you would see 3-terminal regulators on each 
board, like 7805 or similar.

    Bob


--------------------------------------------
On Sun, 2/7/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Sunday, February 7, 2016, 9:17 PM
 
 
  
 
 
 
   
 
 
     
       
       
       okay thanks - yes that sure makes sense - and yes I
 even tried firing it up without the ground wire connected
 once (just to see) but no difference. But yeah that makes
 lots of sense... I wasn't sure to what degree the board
 power was being 'mediated' by the processor or any
 other devices - though I don't see why it would...
 
     
      
 
     
     
 
 
 
 #yiv3869858389 #yiv3869858389 --

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-08 by jw_dewdney@yahoo.com

Bob - just found a few components i missed (!!) - the TH1 (whatever that is.... oscillator??) - and on of the resistors (d'oh!) - so that should help things. Still not working though -

question: " Do the vias all have to be filled/soldered??"

- I'd assumed not since they were (presumably plated through... but just in the off chance I somehow missed this.

Thanks for all your help today by the way.

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-08 by Bob Grieb

TH1 is probably a thermistor, a temperature-dependent resistor.
Guessing it's there to help stabilize the LFO frequency as the 
temperature changes.   The transistor that it's hooked to will 
change a little with temp, so having the resistor change as well
sort of cancels that out.

You don't need to worry about the vias.   Only pc bds damaged 
by corrosion have issues with them.  

I am guessing that you don't have an oscilloscope, right?
Did you get a good 5V on the KLM-367 yet?

Good luck,

    Bob

--------------------------------------------
On Mon, 2/8/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:
Show quoted textHide quoted text
 Subject: Re: [PolySix] Re: The Post I didn't want to make....
 To: PolySix@yahoogroups.com
 Date: Monday, February 8, 2016, 12:30 AM
 
 
  
 
 
 
   
 
 
     
       
       
       Bob - just  found a few components i missed (!!) -
 the TH1 (whatever that is.... oscillator??) - and on of the
 resistors (d'oh!)  - so that should help things. Still
 not working though - 
 
 question: " Do the vias all have to be
 filled/soldered??" 
 
 -
 I'd assumed not since they were (presumably plated
 through... but just in the off chance I somehow missed
 this.
 
 Thanks for all your
 help today by the way.
 
     
      
 
     
     
 
 
 
 #yiv4330695207 #yiv4330695207 --

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-08 by jw_dewdney@yahoo.com

Hi Bob... actually i realized about five minutes after posting that was the thermistor, though i missed it because i was working rather slavishly from Jed's spreadsheet which didnt seem to have it on there.

i DO have a scope actually. a lovely Tek 2445A. however I'm a bit intimidated about troubleshooting logic circuits and signals....ive only ever used it for analogue audio stuff really... so theres more to learn for me.

And i DID get some more functioning 5v test points on the board though still not TP1 which is zero... and TP2 is a bit low at 4.1v or thereabouts. I am a bit confused as the manual uses a totally different language like 'TP-J7' and i am not sure how they correspond to the board ...

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-09 by <backshall1@bellsouth.net>

You are probably talking about the spreadsheet of available parts. If a part is no longer available at big parts places like Mouser, Digikey and Farnell, then it was left off the list a few years ago, although I see some of the unavailable parts have been added in as “Salvage”. I guess this is another one for Jed to add. Salvage the thermistor.
Don B.
Show quoted textHide quoted text
From: mailto:PolySix@yahoogroups.com 
Sent: Monday, February 8, 2016 12:51 PM
To: PolySix@yahoogroups.com 
Subject: Re: [PolySix] Re: The Post I didn't want to make....

  
Hi Bob... actually i realized about five minutes after posting that was the thermistor, though i missed it because i was working rather slavishly from Jed's spreadsheet which didnt seem to have it on there.  


i DO have a scope actually. a lovely Tek 2445A. however I'm a bit intimidated about troubleshooting logic circuits and signals....ive only ever used it for analogue audio stuff really... so theres more to learn for me.

And i DID get some more functioning 5v test points on the board though still not TP1 which is zero... and TP2 is a bit low at 4.1v or thereabouts. I am a bit confused as the manual uses a totally different language like 'TP-J7' and i am not sure how they correspond to the board ...

Re: [PolySix] Re: The Post I didn't want to make....

2016-02-09 by <backshall1@bellsouth.net>

Oops, there it is on page 10.
Show quoted textHide quoted text
From: backshall1@bellsouth.net 
Sent: Monday, February 8, 2016 10:07 PM
To: PolySix@yahoogroups.com 
Subject: Re: [PolySix] Re: The Post I didn't want to make....

You are probably talking about the spreadsheet of available parts. If a part is no longer available at big parts places like Mouser, Digikey and Farnell, then it was left off the list a few years ago, although I see some of the unavailable parts have been added in as “Salvage”. I guess this is another one for Jed to add. Salvage the thermistor.
Don B.

From: mailto:PolySix@yahoogroups.com 
Sent: Monday, February 8, 2016 12:51 PM
To: PolySix@yahoogroups.com 
Subject: Re: [PolySix] Re: The Post I didn't want to make....

  
Hi Bob... actually i realized about five minutes after posting that was the thermistor, though i missed it because i was working rather slavishly from Jed's spreadsheet which didnt seem to have it on there.  


i DO have a scope actually. a lovely Tek 2445A. however I'm a bit intimidated about troubleshooting logic circuits and signals....ive only ever used it for analogue audio stuff really... so theres more to learn for me.

And i DID get some more functioning 5v test points on the board though still not TP1 which is zero... and TP2 is a bit low at 4.1v or thereabouts. I am a bit confused as the manual uses a totally different language like 'TP-J7' and i am not sure how they correspond to the board ...

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