Re: [PolySix] Re: PROGRESS!!!!
2016-02-13 by jw_dewdney@yahoo.com
Bob, well I can post some links i was reading on the subject... to explain further about the resistor business. But it really doesn t matter... since it was
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Re: [PolySix] PROGRESS!!!!
2016-02-13 by Bob Grieb
Hello, Please forgive me for saying this, but measuring the resistance of a zener diode does not make a lot of sense. This component was designed to break
Re: [PolySix] Re: PROGRESS!!!!
2016-02-13 by Bob Grieb
I suspect you are not applying the 47K resistor correctly. Here is what that procedure is actually doing: The CPU should be held in reset as power is first
Odp: [PolySix] Re: PROGRESS!!!!
2016-02-13 by Roman
MG, EG, VCO, VCA, EFFECTS, PROGRAM sections are on CPU board (middle one), while ARP, KEY ASSIGN are on voice board (right big one). So you know where to
Re: PROGRESS!!!!
2016-02-13 by jw_dewdney@yahoo.com
Thus far the MG, EG, VCO, VCA, EFFECTS, PROGRAM sections have been unresponsive. Though the ARP, KEY ASSIGN and other basic functions seemed to work okay (and
Re: PROGRESS!!!!
2016-02-13 by jw_dewdney@yahoo.com
(though i still find it disturbing that a brand new zener diode was somehow impeding my progress - something I never would have suspected - since I d been over
PROGRESS!!!!
2016-02-13 by jw_dewdney@yahoo.com
WOW. I can hardly believe it - everyone (who I am incidentally VERY thankful to for their patience) will be greatly relieved to know that I think i ve LICKED
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by Bob Grieb
I have the code image, if anyone needs it. Bob ... On Fri, 2/12/16, grantbt@jps.net [PolySix] wrote: Subject: Re: [PolySix] Re: The
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by <backshall1@bellsouth.net>
Andy Jury burned an 8749H for me a few years ago. It’s pin-compatible with 8048 and might be easier to find. Don B. From: mailto:PolySix@yahoogroups.com
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by Roman Sowa
I d say you should try to resolve problem with comparator voltages you measured, because of them 8048 is held at reset and will not start whatever replacement
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by grantbt@jps.net
Regarding the 8048, I m guessing you could replace that with an equivalent part burned with the P6 code in it. I don t recall making one myself but I can look
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by jw_dewdney@yahoo.com
ahhhh... i see... funny that s what I previously thought - though I ve managed to convince myself over the last few months that it was just a stock 8048
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by Bob Grieb
I suggest you fix the problem that has already been identified. Then see where you stand. No point in simply replacing things because you can. ... On Thu,
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by Bob Grieb
The 8048 has the code for a Poly6 in it. You can t replace it unless you get a chip from another poly six. ... On Thu, 2/11/16, jw_dewdney@yahoo.com [PolySix]
Re: [PolySix] Re: The Post I wanted to make....
2016-02-12 by jw_dewdney@yahoo.com
yes - sure. that makes the utmost sense. Though maybe trying a brand new processor might not be a bad idea either - as the old one was pretty lousy with
Re: [PolySix] Re: The Post I wanted to make....
2016-02-11 by Bob Grieb
If reset is asserted, that should be the first priority, in my opinion. The cup is not executing code, so there is no way it can work. Bob ... On Thu,
Re: [PolySix] Re: The Post I wanted to make....
2016-02-11 by jw_dewdney@yahoo.com
thanks Bob... though in this case my zeners do not seem to have any printing on them. but i guess that s a mistake i won t be making again. i am sorry to
Re: [PolySix] Re: The Post I wanted to make....
2016-02-11 by Bob Grieb
Also, most of the switching diodes I have seen say 4148 or 914 on them Zener numbers are 4733 or similar. Pretty different. ... On Thu, 2/11/16, Bob Grieb
Re: [PolySix] Re: The Post I wanted to make....
2016-02-11 by Bob Grieb
Zener diodes are made to break down with reverse voltage If you put a ten k resistor in series and then apply six volts with a power supply in the reverse
Re: [PolySix] Re: The Post I wanted to make.... [1 Attachment]
2016-02-11 by jw_dewdney@yahoo.com
well it s great that you mentioned that - I THINK I spotted a ZENER instead of a 1N4148 at D3.... though it s a bit hard to tell them apart... Perhaps a ZENER
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by jw_dewdney@yahoo.com
Yes - i totally agree with that! No reason to change something if they are known good components - esp. with caps - I think there s a lot of people who
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by jw_dewdney@yahoo.com
.... because of the aforementioned probe problems - i couldn t trust ANYTHING i was seeing on the screen - turned out one of my two x10 probes wasn t talking
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by <backshall1@bellsouth.net>
Don’t go replacing all the resistors because of unusual capacitance readings if you are doing the readings with the resistors soldered to the board. In fact
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by jw_dewdney@yahoo.com
oh Bob you are such a tease! :) no but ... i am deeply grateful for your help. i am in here way over my head... i was hoping that if i did everything by the
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by Bob Grieb
Some reason you don t want to read voltage and frequency off the screen of your scope? One pin of the oscillator will look more sinusoidal. The other will
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by Bob Grieb
My posts were intended to give you some info that would help you troubleshoot the reset circuit. Better for you to figure out how this simple circuit works
Re: [PolySix] Re: The Post I wanted to make.... [1 Attachment]
2016-02-10 by Roman Sowa
I think you should see about 1V at pin 2. Since it s nearly 0, my guess is that D2 (3.9V zener) is missing or burned out, or there is a short somewhere around
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by jw_dewdney@yahoo.com
actually i discovered the probe i was using was bad - not only semi intermittent but it was a 10x probe that didn t trigger the 10x compensation on the scope
Re: [PolySix] Re: The Post I wanted to make....
2016-02-10 by Roman Sowa
Maybe that s just faulty/dirty/corroded range switch on the scope. Try to turn it like crazy quite a few times so the contatcs should wipe out a bit and clean.
Re: The Post I wanted to make....
2016-02-10 by jw_dewdney@yahoo.com
Bob..? you around? (the above posts were for you)
Re: [PolySix] Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
fair enough eidorian_aladan... though this scope s adjustment range is only ± 50% max. Everything else was zeroed out - been using scopes for 40 years - but
Re: [PolySix] Re: The Post I wanted to make....
2016-02-09 by eidorian@aladan.net
I don t mean to insult you, but if you re new to scopes then you might not be aware that many have adjustable attenuation controls on X/Y inputs, via either or
Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
so i scoped the pins on the 8048. pin 2 gave me a pretty healthy looking hf sine wave. pin 3 gave me a rather lumpier looking sine at about a thurd the
Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
also currently having super annoying scope issues (needs service i guess) with the scope losing signal at vertical scaling below 1v/div and also only able to
Re: [PolySix] Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
I will try swapping out IC5 for another just in case this one is bad... getting totally different readings from IC6 - which is also a LM393.
Re: [PolySix] Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
curious how when I post from the tablet (ipad) the post happens instantly - whereas posting from the computer (firefox) takes about an HOUR to show up...
Re: [PolySix] Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
testing
Re: [PolySix] Re: POLYSIX SRAM CHIP REPLACEMENT?
2016-02-09 by Roman Sowa
yes, that was 32KB part, basicaly the smallest one you can get in reasonable prices now. In first version the PCB was ready for banking, few of address lines
polysix TC5514APL-3 from aliexpress
2016-02-09 by reboot@hotmail.com
hello i ordered this and they all works , in case of ... Free shipping 10pcs/LOT Original New TC5514APL 3 DIP18-in Integrated Circuits from Electronic
Re: POLYSIX SRAM CHIP REPLACEMENT?
2016-02-09 by grantbt@jps.net
That s cool Roman. I assume you can t buy the original SRAM in SMD, so it must e much larger. Any chance there is banking allowed for? ;-) GB
Re: [PolySix] Re: The Post I wanted to make....
2016-02-09 by Bob Grieb
If reset is at 0.24V relative to ground, then the CPU is being held in reset. It s an active low input, so it s active. Measure pins 5, 6, and 8 of IC5 please.
Re: The Post I wanted to make....
2016-02-09 by jw_dewdney@yahoo.com
HI Bob - sorry it took me awhile to dig the scope out and find the probes etc. So - I got it all up and running and damned if i can see a signal ANYWHERE. From
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. From: backshall1@bellsouth.net Sent: Monday, February 8, 2016 10:07 PM To: PolySix@yahoogroups.com Subject: Re: [PolySix] Re: The
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
The Post I wanted to make....
2016-02-08 by Bob Grieb
That s great news. We can help you a lot more easily if you have a scope. Probe TP4, pin 32 of the MCU. Connect the scope probe gnd to TP3 or the big gnd
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
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
Re: [PolySix] Re: POLYSIX SRAM CHIP REPLACEMENT?
2016-02-08 by Roman Sowa
FWIW, I ve made pin-for-pin replacement of the RAM using regular low power RAM SMD chip and PCB adapter with pins. Only slightly wider than real chip. Still
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.
Re: [PolySix] Jorgensen KLM367 Bug Alert - C22
2016-02-08 by Jed Jorgensen
Wow, hard to believe a new bug was found so many years in. Nice work! I m on vacation but I ll get that posted on the website soon. Thanks all, Jed On Feb 7,