Hi Florian, Thanks man!

I'm enjoying this, nerd that I am.

Indeed can't get the filter to self oscillate audibly as per your
instructions.

There is signal present at connector 14 pin 5 (I seem to have the "new
production" version).
Pin 1 of connector 14 is this great distorted version of the VCO's...
I'll resist the urge to go hotrodding the synth....

anyway...

Got the SSM2044 datasheet.

I have signal at Pin 1 (input) of the SSM2044 - though much lower in
level, though looking at the schematic theres a 33k resistor in line.

But no signal at Pin 3 (output) of the 2044 - totally dead - with the
controls set right.

I've reseated the 2044 and put a bit of deoxit on the pins and cable
connectors but no go.

Seems like the silence at 2044 pin 3 points to a dead filter chip, do
you think

There are some 2044's on ebay, though some of the other numbers on the
top are different. Do you think that matters

Thanks heaps for your assistance Florian, really appreciated.
Sime



--- In korg_mono-poly@yahoogroups.com , Florian Anwander
<fanwander@...> wrote:

>
> Hi Simon
>
>
>
> > when I play keys, I can hear at very low level noise like the "gate"
> > opening.
> > The VCA envelope controls shape the envelope of this low level noise.
> if you turn all four parameters of the VCA-Envelope fully
> counter-clockwise. Playing a key you should hear a klick. -> if yes ->
> VCA is good and the output socket is good.
>
> Then set
> VCA-Envelope to A=0, D=0, S=10, R=10
> VCF-Envelope to A=0, D=0, S=0, R=0
> VCF Cutoff = 5, Resoncance = 10, Envelope amount = 10(+5)
> press a key several times, you should hear a fast resonance
> "Zongggg"-like sound.
> -> if not -> check the VCF-cutoff-modulation input socket. -> many

other

> problems tooo... ;-/ (see below)
> -> if yes -> turn the cutoff frequency fully clockwise and turn up

noise

> volume: do you hear noise
> If no ->
> If you are keen enough to open up the monopoly (ATTENTION: live
> endangering electric power inside!) set the keyboard to hold, press

four

> notes (or unisono) and check the noise and VCOs signal at pin 1 of
> connector 14 (the connector is at the right hand side of the VCO-pcb
> between the volumes of VCO1 and VCO2). If you do not have an
> socilloscope, the connect the output with an mixer and use the tip of
> another cable, connected to the same mixer as signal search (don't turn
> up the volume too loud, the signals might kill your
> tweeters/headphones/ears).
>
> If there is still nothing to hear I assume that the powersupply is
> defect. If there is something to hear, either the cable between VCO pcb
> and VCF pcb is broken, or the VCF chip SSM2044 is gone. Sometimes the
> 2044 is socketed, then you might check whether the chip is seated ok in
> the socket. But this requires unmounting the pcb from the frontpanel,
> which is not much fun.
>
> Florian
>