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

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

Hi all there, new updates.

ERRATA CORRIGE:

I've made a mistake about the value reading from IC18 pin 7, due to a wrong setup of the oscilloscope.

The actual output value is +15V

KEYBOARD SCALING ISSUE:

I've checked the A B C INH clock values from IC 12 on KLM366 to check VCF clocks.

I've checked the A B C INH clock values from IC 31 on KLM366 to check tuning section clocks.

PC1 replaced with brand new VTL5C9.

The issue is still there, so i guess the problem is somewhere in the assigner section.

As you can see in this pic, 

http://img820.imageshack.us/img820/8370/87ux.jpg

I've already replaced some of the involved chips (IC17, IC18, IC31), before this replacement,

Any idea where to dig?

How can i test if the incoming signals from KLM367-A are ok to be sure that issue is located somewhere on the KLM366 assigner section?

Here some pics of the spare in place.

The spare has been mounted upside/down to match the Anode/Cathode pins.

http://img194.imageshack.us/img194/9278/vy3d.jpg

http://img842.imageshack.us/img842/1684/89ng.jpg

To kenichiproductions

Message 7 of 8 , 

The Mask rom were both original, maybe the huge shortcut area on KLM367 have corrupted the data.

Any help is much appreciated,

Thanks for support.  

 

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

Hi all there,

Some updates:

16' 8' 4' pot issue solved.

The pot wasn't working properly due to a interrupted trace on KLM 367.

You can see the huge rework I've done the first day this P6 come into my lab.

The trace about the 16' 8' 4' pot is the one rejoined with the red cable.

I don't know if I can post here this link to the picture, if not, just tell me and I'll remove it.

http://imageshack.us/a/img607/7356/be7v.jpg

So, only three issues to solve remaining.

KEYBOARD SCALING - I'm waiting for the spares  VTL5C9

FIFTH VOICE SOUNDING SO LOW IN OCTAVE - Under investigation, i've replaced or swapped between voices almost all components on this voice section, still nothing.

PATCHES MEMORY SAVING:

I've found another broken trace in the same area mentioned before, this one involving the  TC5514APL-3 memory chip.

Trace has been restored, but the issue wasn't there.

I'm waiting for spares to replace it, i'll keep you posted about that.

QUESTION:

I've done the battery replacement mod to mount a CR2032.

I've replace the resistor R91 with a 1N4148 diode as i've read on oldcrow's page.

Here a pic of the area, does it seems correct to you?

http://imageshack.us/a/img823/5561/vmeo.jpg

Thanks again for help.

Bye,

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

Hey Sandro,

Thats really interesting that most of your problems came from your CPU chips. Were they original or aftermarket replacements? 

I had weird problems like these but mostly the past they have come down to the CPU socket, or D/A converters. haven't had to replace a CPU yet...

I would definitely put in the new opto coupler. Just really make sure of your connections. I think I had trouble with this one time. And then Retune following peoples advice here or by googling for polysix tuning procedures. I left my most recent one on overnight and touched it up continuously using a chromatic tuner and was able to get it really nicely in tune. I had also replaced all electrolytics on CPU and module board on this unit. There is the fine tuning for the middle of the key span as well which could help. D#-E# or something the trimmer says next to it....

With the RAM chips, usually swapping out the 5514APL has done the trick for me in the past. If not that try replacing the memory address decoder while your at it. Can't recall which IC that is off the top of my head.

Regards,

Luke

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

Hi all there,

that's the last update for today.

WRONG SCALING issue:

I've swapped the 8049-217 from a working P6 to the faulty one and there was a big change.

Now, tuning of notes from the faulty P6 doesn't sound scrambled anymore.

I've followed the tuning tips on service manual and there is a fixed drifting at the same intervals.

i.e.

C4 = C#5

C#4 = D5

D5 = D#5

and so on....

The 8049-217 taken from the faulty P6 mounted on the working P6 caused the notes to play scrambled just as the other one, so part of the issue came from there.

Now, on the faulty P6 (with working 8049-217) there's the old HTV1501 mounted on it, and the IC18 Pin 7 is still stuck at 0V.

----

PATCHES MEMORY SAVING issue.

I've checked the traces from and to the TC5514APL-3 memory chip and seems everything ok.

I've bought spares to replace t in order to verify if the issue is there.

Now i'ts late and i'll go to sleep.

Thanks a lot.

Sandro.

 

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

I can confirm VTL5C9 works fine without any modifications. Made this picture for reference.

http://i188.photobucket.com/albums/z222/minebildererdine/Synth/Korg%20Polysix/PolysixOpto_zps31d9ca46-1.png

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