Vintage Synth Repair

Thanks, I'll take a closer look at those ICs shortly. I did some tests
and none of the LEDs on the voice board are triggered by the keyboard.
Also I noticed that when I flick it on and off a few times sometimes
the LF) 1/2 rate LED is off and other times it's solid on. The rate
nob doesn't control it at all. I looked at the battery and it doesn't
LOOK like it's leaked onto anything, but I'm still gonna test those
chips (or just replace them.)

I'm beginning to wonder if the problem isn't related to the power not
getting to some of the boards... hmmm....



--- In vintagesynthrepair@yahoogroups.com, Scott Nordlund <gsn10@...>
wrote:
>
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> I have a broken DK 600 (with Expander) myself that I hopefully will
be working on shortly.  Get the Opera 6 service manual from Sander
Meyer's website- it *should* be the same as the DK 600 (though I have
heard all sorts of confusing and contradictory info about the Opera 6
and DK 600- you may want to verify, just to be sure, that it
corresponds to what you're actually working on).
> 
> The main problem with the DK 600 (other than the fact that it's a
Siel) is the NiCd memory backup battery, which leaks onto the CPU
board (like in the Polysix).  So the first thing you'll want to do is
check out the CPU board (under the keyboard) and see what's going on
under there.  In anticipation of fixing mine, I've analyzed the
problems that a leaky battery can cause, depending on what chips are
affected.  If IC15 or IC16 are bad, the front panel buttons and/or
tape dump won't work (IC15 buffers panel inputs, IC16 buffers the tape
dump in/out and the front panel "data available" interrupt signal). 
IC20 controls waveform selection.  IC28 and IC29 control display
blanking and the "Enter" LED.  I don't know what would cause the knobs
to not work- check TP8 (multiplexed knob readings). There also should
be LEDs on the voice board connected to gate signals, so you can see
if the voices are being properly triggered.
> 
> To: vintagesynthrepair@yahoogroups.com
> From: cockandswan@...
> Date: Sat, 1 Mar 2008 03:26:56 +0000
> Subject: [vintagesynthrepair] siel dk-600
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>             hey, i just got a siel dk-600 which i am excited about.
it's different
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> than the older synths i've been working on but i thought i'd see if
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> anyone else has any experience trouble shooting these. 
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> problems:
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> it powers up but there's no sound and no response form the
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> buttons/nobs. one of the LEDs is burned out too. i'm hoping that since
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> all the nobs and buttons are non-functional that there is some master
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> routing for the controls that has gone bad. any ideas? how about led
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> replacements? 
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> thanks for all your help guys!
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> -johnny 
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