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PolySix CPU question...

PolySix CPU question...

2015-05-12 by noddyspuncture@hotmail.com

Hi folks,


Not been on here for some time, but I though I'd pop by and see if anyone can advise...?


My PolySix *had* the dreaded battery leak problem before I bought it... and it was fixed up professionally. And a rather good job was made of it by a highly regarded tech. It's been perfect for years... but now I have a problem with it.


All the LED's are lit... it plays "noises" - pitched, so you can still hear "notes" - but non of the front panel controls in the Osc, Filter or Envelope sections work. The effects section controls do respond though. It does seem like the classic battery symptom...


I have meticulously gone over all the usual lines that open with the battery thing... but they all check out OK...!

I suspected the CPU but it has an output and scoping the data lines shows activity.


My question is... does anyone here actually understand how the CPU and all the associated logic IC's work together..? It occurred to me that I don't really understand that theory/side of things... and I would really like to.


Where can I start? Are there any books etc.. that would get me there relatively quickly?

Is it the kind of thing that someone could "explain" to a technically minded person...? I do understand electronics and electronic theory in general but this part is baffling me.


Cheers,

Tom


Re: [PolySix] PolySix CPU question...

2015-05-12 by Bob Grieb

I think I already uploaded a commented copy of the code that runs
the CPU.  You could start by looking at that code.   Everything you want
to know about how that CPU does what it does to control the patch voltages
is right there.

   Bob

From: "noddyspuncture@hotmail.com [PolySix]" <PolySix@yahoogroups.com>
To: PolySix@yahoogroups.com
Sent: Tuesday, May 12, 2015 4:37 PM
Subject: [PolySix] PolySix CPU question...

 
Hi folks,

Not been on here for some time, but I though I'd pop by and see if anyone can advise...?

My PolySix *had* the dreaded battery leak problem before I bought it... and it was fixed up professionally. And a rather good job was made of it by a highly regarded tech. It's been perfect for years... but now I have a problem with it.

All the LED's are lit... it plays "noises" - pitched, so you can still hear "notes" - but non of the front panel controls in the Osc, Filter or Envelope sections work. The effects section controls do respond though. It does seem like the classic battery symptom...

I have meticulously gone over all the usual lines that open with the battery thing... but they all check out OK...!
I suspected the CPU but it has an output and scoping the data lines shows activity.

My question is... does anyone here actually understand how the CPU and all the associated logic IC's work together..? It occurred to me that I don't really understand that theory/side of things... and I would really like to.

Where can I start? Are there any books etc.. that would get me there relatively quickly?
Is it the kind of thing that someone could "explain" to a technically minded person...? I do understand electronics and electronic theory in general but this part is baffling me.

Cheers,
Tom



Re: [PolySix] PolySix CPU question...

2015-05-12 by noddyspuncture@hotmail.com

Thanks Bob, I couldn't open the download, but if that "asm" file is computer code...?!.. I will still have no idea...:(

I was asking if I could get to understand the way it all works using simple words and explanations...?
Computer programming and code is also beyond me.

When I am scoping all the data busses etc... it would be nice to understand what should and shouldn't be there. Just a basic understanding is what I am after so I can stand a chance of tracing faults in that section.

Cheers,
Tom


Re: [PolySix] PolySix CPU question...

2015-05-12 by Bob Grieb

I thought about my post a little more after sending it.  One thing you might try is
downloading a service manual for a different analog synth from about that same time
period.   The Sequential Six Track comes to mind.   The implementation is quite different,
but the basic idea of how it works is similar.   Scanning the front panel, scanning the pots,
feeding out the voltages to the S&H circuitry.  That sort of thing.   And there is a lot of
text that explains how the different sections work.

The Polysix has a lot in common with a lot of other designs from the early 80s.
Many mfrs gave nice descriptions of the basic circuit operation in their service manuals.
(Which you can find with Google in about 10 seconds)

   Bob

BTW, The assembly code may not be that easy to follow, but my listing has comments
throughout that explain what the code is doing.   That's why I mentioned it.

Unfortunately, if you really want to understand what a microprocessor-based system
is doing, the answer is in the code.   Of course it's possible to troubleshoot without
knowing.  Just look for floating signals and bad voltage levels, in the case of the KLM367.
You could print a copy of the KLM schematic and highlight the connections as you test
them with an ohmmeter set to beep on a connection.   It's tedious, but luckily it's not
that big of a board, and the battery damage is usually in a fairly small area.

I guess you are thinking that this may not be from the battery, but some component
failure, right?

From: "noddyspuncture@hotmail.com [PolySix]" <PolySix@yahoogroups.com>
To: PolySix@yahoogroups.com
Sent: Tuesday, May 12, 2015 5:40 PM
Subject: Re: [PolySix] PolySix CPU question...

 
Thanks Bob, I couldn't open the download, but if that "asm" file is computer code...?!.. I will still have no idea...:(

I was asking if I could get to understand the way it all works using simple words and explanations...?
Computer programming and code is also beyond me.

When I am scoping all the data busses etc... it would be nice to understand what should and shouldn't be there. Just a basic understanding is what I am after so I can stand a chance of tracing faults in that section.

Cheers,
Tom




Re: [PolySix] PolySix CPU question...

2015-05-13 by Roman Sowa

have you tried to reconnect every connector several times so any
possible corrosion or dirt gets wiped out. A tiny bit of corrosion might
have spread more over those years.
Looks like there's some line malfunctioning between panel boards and KLM367

Roman

W dniu 2015-05-12 o 22:37, noddyspuncture@hotmail.com [PolySix] pisze:
>
>
> Hi folks,
>
>
> Not been on here for some time, but I though I'd pop by and see if
> anyone can advise...?
>
>
> My PolySix *had* the dreaded battery leak problem before I bought it...
> and it was fixed up professionally. And a rather good job was made of it
> by a highly regarded tech. It's been perfect for years... but now I have
> a problem with it.
>
>
> All the LED's are lit... it plays "noises" - pitched, so you can still
> hear "notes" - but non of the front panel controls in the Osc, Filter or
> Envelope sections work. The effects section controls do respond though.
> It does seem like the classic battery symptom...
>
>
> I have meticulously gone over all the usual lines that open with the
> battery thing... but they all check out OK...!
>
> I suspected the CPU but it has an output and scoping the data lines
> shows activity.
>
>
> My question is... does anyone here actually understand how the CPU and
> all the associated logic IC's work together..? It occurred to me that I
> don't really understand that theory/side of things... and I would really
> like to.
>
>
> Where can I start? Are there any books etc.. that would get me there
> relatively quickly?
>
> Is it the kind of thing that someone could "explain" to a technically
> minded person...? I do understand electronics and electronic theory in
> general but this part is baffling me.
>
>
> Cheers,
>
> Tom
>
>
>
>
>

Re: [PolySix] PolySix CPU question...

2015-05-13 by chipaudette@yahoo.com

Also, it's important to remember that the Polysix has two CPUs: (1) the key assigner CPU and (2) the CPU that handles everything else (servicing all the push buttons and knobs, saving and recalling patches, etc).

The key assigner handles everything that's "fast".  Primarily, it scans the keybed to look for which keys are pressed and then it continually updates the pitch CV to each of the six voices (multiplexed).  It does this in a fast loop that cycles every 6 milliseconds or so.  I replaced my key assigner CPU with an Arduino, so I had to reverse engineer most of its functions.  You can read about its basic timing loop here:

The other CPU operates independently.  It scans all the user controls (push buttons and knobs) and creates control voltages based on these settings in order to drive the synth voices.  I don't know much about this CPU as it was far less interesting to me than the key assigner.  Depending upon what you want to learn about, however, this might be exactly what interests you.

Hope that this helps,

Chip

Re: [PolySix] PolySix CPU question...

2015-05-13 by Florian Anwander

Hello,

basically the work of the CPU is: addressing something, then reading or writing the addressed source/destination.
To my experience (two polysixes recovered), the first thing to do, is to check all address destinationes, whether there are changing signals. Usually there are two stages of addressing at one chip: the direct address from the CPU and a chip-enable signal (or similar).

I would first check all address lines on the panel boards, then all address lines on the data delivery side (CPU board and voice board).

Florian

On 12.05.15 22:37 , noddyspuncture@hotmail.com [PolySix] wrote:
 

Hi folks,


Not been on here for some time, but I though I'd pop by and see if anyone can advise...?


My PolySix *had* the dreaded battery leak problem before I bought it... and it was fixed up professionally. And a rather good job was made of it by a highly regarded tech. It's been perfect for years... but now I have a problem with it.


All the LED's are lit... it plays "noises" - pitched, so you can still hear "no tes" - but non of the front panel controls in the Osc, Filter or Envelope sections work. The effects section controls do respond though. It does seem like the classic battery symptom...


I have meticulously gone over all the usual lines that open with the battery thing... but they all check out OK...!

I suspected the CPU but it has an output and scoping the data lines shows activity.


My question is... does anyone here actually understand how the CPU and all the associated logic IC's work together..? It occurred to me that I don't really understand that theory/side of things... an d I would really like to.


Where can I start? Are there any books etc.. that would get me there relatively quickly?

Is it the kind of thing that someone could "explain" to a technically minded person...? I do understand electronics and electronic theory in general but this part is baffling me.


Cheers,

Tom