Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

---In PolySix@yahoogroups.com, <polysix@yahoogroups.com> wrote:

I posted this link a couple of months ago.It’s a blog by Stefan Huebner. He took some measurements with an oldP1501 and a couple of Vactrol parts and made a nice chart showing response curves.His conclusion: The VTL5C9 is a much closer match to the old P1501 than any ofthe parts we have been trying. I think he may be right since I had trouble witha new VTL5C3 in one Polysix not scaling properly and a VTL5C9 worked just fine.I’ve never used the 5-pin VTL5C3/2 dual photocoupler, since there areonly 4 pins on the Polysix that are actually connected to anything.

 http://huebnerie.de/blog/?p=318

 

Don Backshall

 

---

From: PolySix@yahoogroups.com [mailto: PolySix@yahoogroups.com ] On Behalf Of rufushaw@...
Sent: Wednesday, October 30, 20132:29 PM
To: PolySix@yahoogroups.com
Subject: [PolySix] RE: Another P6back to life, but some issues are still there.

 

 

 Hiall there,

 

Some updates:

 

MG LEVEL issue > Solved.

After getting crazy in debugging, I've swappedthe 8047-347 (an 8947 with mask rom written on it) with a regular factory 8047.the issue disappeared.

Called the guy who copied the maskrom for me, hegave me another copy an this one works flawless.

 

------

 

WRONG SCALING issue:

is still there.

 

I've bought some NOS VTL5C3/2 photocouplers.

I've replaced the original HTV1510 mounting theVTL5C3/2 upside-down to match pinouts.

This doesn't solve the issue.

Measured the IC18 pin 7, obtaining 0V

After that, i've tried to replace the R39 with a22K resistor. nope.

 

Placed back the original HTV1510 and originalR39 resistor, measured again the IC 18 pin 7. obtaining 0V just as before.

 

IC 31 Replaced

IC 18 Replaced

IC 17 Replaced

 

I have no points to where i'm going nor where togo.

 

------

 

PATCHES MEMORY SAVING issue.

I haven't checked it at all, is still there justas before.

 

 

 

---In polysix@yahoogroups.com, <rufushaw@...> wrote:

 

Hithere,

 

Someupdates.

 

I'vemade some swapping tests, and these are the result.

 

BrokenP6 had some issues on panel controls, on octave transpose knob 16' 8' 4' and MGlevel knob.

 

I'veswapped the KLM367 with a working one, and both these issues disappeared, so,the panel board with knobs is ok and the problem is somewhere on KLM 367.

 

I'veordered some Vactec VTL5C3/2 to change the PC1 IC, hope this will beenough to restore the voice board.

 

Soquestions are:

 

Whichtraces / ICs manage the OCTAVE TRANSPOSE switch 16' 8' 4' 

Which traces / ICs manage the MG level potvalues?

 

Any help is very much appreciated, thanks.

 

 

 

 

---In polysix@yahoogroups.com, <rufushaw@...> wrote:

Hi all there,

 

I've picked upanother Polysix in good external conditions, but dead on the electronic side.

 

It had the commonbattery leakage on a small area not so bad than others that I've alreadyrepaired, so I've restored it at usual,

 

Now some minorissues are still there.

 

Octave scaling isirregular, so, suspecting a faulty HTV1501 photocopupler as written in othertopics, I've swapped the voice board with a spare working one, and the issuedisappeared, then the issue might be on PC1.

I can't understandwhich spare is better for this IC, someone says VTL5C1, some othersays VTL5C3, 

 

MG level doesn'tworks properly.

This issue isdriving me crazy.

Frequency andDelay Pots are working flawless, but once engaged, it's impossible to dim orturn off the LFO modulation effect by turning the "level" pot.

The pot itself isworking, either the IC2 4051 on control board is working, i've followed theData and A B C cables for signals routing and they are without anyinterruption.

I've checked theIC6 also, perfect.

Connection cablesare ok.

Tips about whereto dig?

 

More than this, itdoesn't save patches.

I've checked thememory chip's electrical signals, and it seems working properly, giving thesame responses than the working one.

.

I have also madethe Lithium battery mod as shown in service manual appendix, but there's no wayto save patches,although  the buttons are working properly.

 

 

Any help is verymuch appreciated, thanks.

Sorry for my badenglish,

Bye,