To: vintagesynthrepair@yahoogroups.com
From: cockandswan@...
Date: Tue, 23 Dec 2008 17:58:26 +0000
Subject: [vintagesynthrepair] Re: Siel DK 600, strange problem
weird problem. i have a DK 600 too and it doesn't really work at all.
i turn it on and can sometimes get the first lfo's led to flash and
one of the digits on the display to light up, but that's it. i've been
shotgunning ICs on the board underneath the keyboard and somewhere in
there i got the other digit on the display working and i even got a
couple of the voice chip LEDs to light, but now it's back to normal.
any thoughts? (i replaced the battery too, though i don't think it was
leaky)
thanks,
johnny
--- In vintagesynthrepair@yahoogroups.com, Scott Nordlund
wrote:
>
>
> I repaired the NiCd battery corrosion problem in my Siel DK 600 (and
also the Expander module), then attempted to address a CV demux/sample
and hold problem (envelope release time was too short because a
defective component was draining the charge from the capacitor). I
replaced the associated parts (4051 and TL084), and it fixed the
problem, but also introduced some new ones. The CVs associated with
these chips (filter cutoff, oscillator detune, etc.) are unstable when
the synth is first switched on, and will actually change (in an
interesting way) when there's some kind of mechanical vibration. It
mostly resolves after the synth has had a few minutes to warm up. I
do appreciate the added "vintage driftiness" and "innovative
performance controls", but I'd really rather have it do what I want it
to do. I've tried reseating the chips.
>
> It won't be a big deal to just rework the whole thing by replacing
all the parts (sockets included) and then thoroughly cleaning off the
flux, but the crappy DIP connectors seem to have a very limited
lifespan and I don't really want to go plugging and unplugging any
more than absolutely necessary. I'd like to fix it and be done with
it. I'll redily admit that using salvaged components (sockets even)
probably isn't the best idea, but I'm too cheap and lazy to order
parts, and it's probably not any more likely to cause problems than
the original flaky construction.
>
> So based on this, is the problem more likely to be a bad solder
joint or bad socket, or is the solder flux on the board interfering
with the high impedance stuff? I'd guess the former, but again I
don't want to risk breaking a pin on a DIP connector if I have to
rework it again.
>
> There's also some sort of interference that seems to affect the
pulsewidth and cutoff CVs (?) of voices 5 and 6. I probably won't be
able to address this without an oscilloscope, but it's not extremely
intrusive, so it can wait (though I'm also open to suggestions here!).
>
> __________________________________________________________
> Windows Live Hotmail now works up to 70% faster.
>
http://windowslive.com/Explore/Hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_faster_112008
>
i turn it on and can sometimes get the first lfo's led to flash and
one of the digits on the display to light up, but that's it. i've been
shotgunning ICs on the board underneath the keyboard and somewhere in
there i got the other digit on the display working and i even got a
couple of the voice chip LEDs to light, but now it's back to normal.
any thoughts? (i replaced the battery too, though i don't think it was
leaky)
thanks,
johnny
--- In vintagesynthrepair@yahoogroups.com, Scott Nordlund
wrote:
>
>
> I repaired the NiCd battery corrosion problem in my Siel DK 600 (and
also the Expander module), then attempted to address a CV demux/sample
and hold problem (envelope release time was too short because a
defective component was draining the charge from the capacitor). I
replaced the associated parts (4051 and TL084), and it fixed the
problem, but also introduced some new ones. The CVs associated with
these chips (filter cutoff, oscillator detune, etc.) are unstable when
the synth is first switched on, and will actually change (in an
interesting way) when there's some kind of mechanical vibration. It
mostly resolves after the synth has had a few minutes to warm up. I
do appreciate the added "vintage driftiness" and "innovative
performance controls", but I'd really rather have it do what I want it
to do. I've tried reseating the chips.
>
> It won't be a big deal to just rework the whole thing by replacing
all the parts (sockets included) and then thoroughly cleaning off the
flux, but the crappy DIP connectors seem to have a very limited
lifespan and I don't really want to go plugging and unplugging any
more than absolutely necessary. I'd like to fix it and be done with
it. I'll redily admit that using salvaged components (sockets even)
probably isn't the best idea, but I'm too cheap and lazy to order
parts, and it's probably not any more likely to cause problems than
the original flaky construction.
>
> So based on this, is the problem more likely to be a bad solder
joint or bad socket, or is the solder flux on the board interfering
with the high impedance stuff? I'd guess the former, but again I
don't want to risk breaking a pin on a DIP connector if I have to
rework it again.
>
> There's also some sort of interference that seems to affect the
pulsewidth and cutoff CVs (?) of voices 5 and 6. I probably won't be
able to address this without an oscilloscope, but it's not extremely
intrusive, so it can wait (though I'm also open to suggestions here!).
>
> __________________________________________________________
> Windows Live Hotmail now works up to 70% faster.
>
http://windowslive.com/Explore/Hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_faster_112008
>
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