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<p>Good work! Always a relief when a trivial (albeit elusive!) cause
is found.</p>
<p>I had a similar issue with a Roland MSQ700 MIDI sequencer where
it was not responding to some of the push buttons. Turned out to
be a few invisible hairline cracks running thru the front panel
PCB.</p>
<p>- Oren<br>
</p>
<div class="moz-cite-prefix">On 5/11/23 12:07 PM, g m montalbano via
Synth-diy wrote:<br>
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cite="mid:CADTo2MuBspMuMGVNDJDmHResNm43kTjx8jW5FeoF-RqajMH3eA@mail.gmail.com">
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<div>Finally solved this -- and I'm sorry to say it's not very
interesting.</div>
<div><br>
</div>
<div>There was a microscopic break in one of the ground traces
going to the 60 pin connector on the voice board. When
pressing the meter probe to it, it made contact and showed as
good; with the probe removed, contact was lost, and the tune
circuit was lost.</div>
<div><br>
</div>
<div>Hope to come up with something more interesting &
illuminating next time.<br>
</div>
<div><br>
</div>
<div>Thanks to everyone who contributed ideas.</div>
<div><br>
</div>
<div>~GMM<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, May 3, 2023 at 8:32 PM
Michael E Caloroso <<a
href="mailto:mec.forumreader@gmail.com"
moz-do-not-send="true" class="moz-txt-link-freetext">mec.forumreader@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Short the TUNE button contacts. This will loop
the autotune process then you can start probing on the
'scope.
<div><br>
</div>
<div>I know that a DC offset at the audio autotune summing
buss will mess up the autotune algorithm. Check each
voice audio at the summing buss for DC.</div>
<div><br>
</div>
<div>MC</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, May 3, 2023 at
9:23 PM brianw <<a
href="mailto:brianw@audiobanshee.com" target="_blank"
moz-do-not-send="true" class="moz-txt-link-freetext">brianw@audiobanshee.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Indeed. Tests have
confirmed that the EPROM chips (I think there are three)
have the full and uncorrupted tuning subroutines in them,
because the same digital CPU board can tune a known-good
analog Voice board.<br>
<br>
You're lucky to have spare working P5R2 boards for these
diagnostics (despite the frustration so far).<br>
<br>
Brian<br>
<br>
On May 3, 2023, at 3:45 PM, g m montalbano wrote:<br>
> All very true. However, the problem isn't on the CPU
board, since that board works correctly with another Voice
board.<br>
> The power supply, front panel,CPU board and 60 pin
cable are all good --the fault is on the Voice board.<br>
> <br>
> On Wed, May 3, 2023 at 2:49 PM Jay Schwichtenberg
wrote:<br>
>> For somethings not in the analog realm.<br>
>> <br>
>> One of the first things to check in old systems
like these after the <br>
>> power supplies is the reset circuit.<br>
>> <br>
>> If I remember correctly there are multiple
EEPROMs in it. Could be the <br>
>> tuning code in one of them could of gone bad.
EEPROMs don't last forever <br>
>> and if the code is bad the processor would wonder
off into oblivion.<br>
>> <br>
>> Might very carefully pull the EEPROMs and reseat
them to see if a socket <br>
>> connection might of gone bad too.<br>
>> <br>
>> These are they types of problems logic analyzers
are good for. Big pain <br>
>> to setup but the problem maybe a lot easier to
find.<br>
>> <br>
>> Jay S.<br>
> <br>
<br>
<br>
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