Discussion about the Korg PolySix synthesizer

FIXED !!

I found that the "technician" who tried to fix it before, put one 
4011 in the wrong direction on the Synth control panel...
fixing that caused the synth section EG/Filter/VCO to respond 
correctly. 

I alos retraced a few traces at the circuits of Voice 6 and 7 on the 
Strings Keyboard Tracking board, and replace two LM chips; replaced a 
few 4xxx chips on the Synth board - where I found the stample between 
of on of the ICs legs, retrace the left are on the Signal Generator 
board who had some corrosion on it and also the 6 caps on the upper 
connector, repalced the TL9130 chip on the Strings board which 
connects to the octave selector (16' and 8' didn't work), adjustted 
the reset trimmer in the computer board as noted before and replaced 
the two 4051 where the control panel gets in (before I realized the 
mistake of that "technician", and a few more things  (including 
recapping where needed)

All in all I find it a beautiful instrument, especially for strings 
and brasses !

Going to build a MIDI IN retrofit to it soon and mod to Lithium 
battery support.

BTW, does it make sense that once I replaced the electrolytic 
capacitors on the KBD Track Strings board, the sound got less fat ?

I once replaced a few capacitors in a Hi-Fi amp with chinese ones and 
notice that it didn't sound as good. It has Elna caps (like on the 
Trident) before, and once I got them back it had its sound again.



--- In PolySix@yahoogroups.com, Johannes Hausensteiner <johau@g...> 
wrote:
> It seems that there is a problem with the CV:
>  > PM doesn't play sound, and PWN plays a what sounds like a
>  > contineous "ta-ta-ta-ta-ta".
> Probably the PW control is at maximum.
> 
> I only have the schematics of Trident MK I (you can find it at
> "old Crow's"). It is very similar to MK II except for the synth
> section, especially the "Programmer". But we know that the
> programmer CPU is the same as on the Polysix, so the Programmer
> board will be similar to KLM-367.
> 
> You can measure the multiplexed analog CVs e.g. on pin 3 of
> the 4051 demuxers with oscilloscope. Obtain trigger at 32 of
> Programmer CPU. You should see all control voltages in a
> time-multiplexed fashion. From missing / sticking CVs you may
> draw next conclusions.
> 
> Hope this helps
> 
> Johannes
> 
> P.S:
> Funny enough, they did not use a microprocessor for storing
> patches in the MK I but a very simple counter driven mechanism.
> Analog controls were at 6 bits resolution, the same as digital
> switches! Multi-switches (e.g Wavefrom) are built via a resistor
> ladder/divider. At the output side the digital signals are
> recreated by means of window comparators.
> Furthermore the "Piano" and "Clavi" Presets had a set of
> controls (separate trim pots / fixed dividers) of their own
> like the presets in the CX3 organ. Yamaha use a similar technique
> in their CS-60 and CS-80 synthesizers. In the CS-60 you could save
> *one* (!!) patch besides the "Manual" setting, in the CS-80 it
> was the amazing number of 4 patches that could be "saved" by
> setting the patch parameters by a second set (3., 4., 5.) of
> sliders normally hidden under a flap in the control panel.
> 
> 
> 
> 
> 
> gil_we wrote:
> > Current situation -
> > 
> > Trident powers up correctly, String section works OK except for 
> > unable to click the 16' and 8' on/off. Besides all section works.
> > Brass section doesn't play any sound. Synth section plays the saw 
> > waveform ok, PM doesn't play sound, and PWN plays a what sounds 
like 
> > a contineous "ta-ta-ta-ta-ta". VCF sectiob doesn't make any 
change 
> > to sound.
> > 
> > 
> > What I did so far -
> > 
> > 1. changes battery to another NiCAD battery of 3.6v - don't know 
how 
> > much Ah it is (can this be the problem ?)
> > 
> > 2. Retraced two black traces on the computer/battery board (I 
can't 
> > see any corroded traces / parts other than those)
> > 
> > 3. Replaced all 4xxx ICs in the synth board as I found a staple 
> > between the legs of one of them.
> > 
> > 4. Cleaned the corrosion of a few traces on the oscillator board, 
> > these are the traces that are placed under the coputer board, 
right 
> > under the bettry position.
> > 
> > Any directions / idea ?
> > 
> > Thanks
> >  
> > 
> > 
> > 
> > --- In PolySix@yahoogroups.com, "gil_we" <gil_we@y...> wrote:
> > 
> >>Thanks !!
> >>
> >>I made a search here and found that by the Polysix service manual,
> >>VR1 on the computer board is supposted to be responable for the 
> > 
> > reset.
> > 
> >>I changed VR1 setting on the Trident and now the leds/banks seems 
> > 
> > to 
> > 
> >>work OK ! i.e they do not lite up contantly as before, but acts 
> > 
> > what 
> > 
> >>seems to be normally (I can select presets / write)
> >>
> >>Still I find that the Synth section plays hiss and noise (no 
> > 
> > sound) 
> > 
> >>as well as the brass section.
> >>
> >>The Strings section seems to function (beautiful sound !) as well 
> > 
> > as 
> > 
> >>the effects (flanger, vibrato, ensemble, bowing, joystick)
> >>
> >>The sting section even sounds quite tuned (surprisingly...)
> >>
> >>So now the main problem is the misfunction / silent of the brass 
> > 
> > and 
> > 
> >>synth section.
> >>
> >>I'll retrace the other what-seems-to-be bad traces on the other 
> > 
> > board 
> > 
> >>(voice?) and see if that helps.
> >>
> >>Any other ideas at the meantime ?
> >>
> >>Thanks !!
> >>
> >>
> >>
> >>
> >>
> >>
> >>--- In PolySix@yahoogroups.com, "Chromatest J. Pantsmaker" 
> >><chromatest@g...> wrote:
> >>
> >>>----- Original Message -----
> >>>From: gil_we <gil_we@y...>
> >>> 
> >>>
> >>>>Also, I can see a few partially black traces on the KLM-379B 
> >>
> >>board,
> >>
> >>>>right at the place that is below the battery.
> >>>
> >>>I'd start here.  Get a nice voltmeter and visually and 
> > 
> > mechanically 
> > 
> >>trace all of the darkened traces.  I bet a couple of those are 
> >>hosed...
> > 
> > 
> > 
> > 
> > 
> > 
> > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> >