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--></style><title>Re: [sdiy] Oberheim OB-XA autotune procedure
questions</title></head><body>
<blockquote type="cite" cite><font face="Arial" size="-1">Hi
all,</font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">I've just
finished replacing the battery in my OB-XA (along with installing new
bushings and cleaning some problematic J-wires) and I've found that
all voices now fail the autotune procedure. When I press the
button, it cycles through all 8 voices, then the 8 LEDs
flash for about 2 seconds. All 8 voice cards are perfectly
functional.</font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">I have both
versions of the service manual, and neither address the autotune
function other than using it in calibration routines. How
autotuning is implemented and any specific troubleshooting/calibration
strategies are completely neglected.</font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">So I'm
wondering what could possibly be contributing to this problem.
Autotune worked before the battery replacement, although tuning wasn't
perfect. Does something within the circuit rely on battery power
to retain memory for the
autotune algorithm? </font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">At first I
thought bad tuning might be causing the problem. Turning the
voice disable feature off with the test2 switch, I've started
calibrating the individual voice boards to achieve better tuning, yet
reagardless of the more accurate initial tuning the autotune function
still does not want to cooperate.</font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">Looking back
at the AH archives, it seems a few people have experienced this exact
problem, though no answer ever surfaced. </font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1">...Anyone?</font></blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1">Thanks.</font></blockquote>
<div><br></div>
<div><br></div>
<div>Any time one works on something vintage, strain is placed on
solder connections, connectors, etc.</div>
<div>Very likely you inadvertently moved something and it caused
this.</div>
<div><br></div>
<div>Generally the biggest problem I see with people attempting their
own work on vintage synths or anything else (and no slam personally)
is assuming that what they know is all they'll need. It's *always*
what you don't know that will bite you. With that said, I'd recommend
going over your work carefully and inspecting everything closely under
bright light. Power supply solder connections are notorious for being
bad on OB-Xas, along with their connector pins. I won't work on one
without flipping that board to see what's up even before I power it
up.</div>
<div><br></div>
<x-sigsep><pre>--
</pre></x-sigsep>
<div>Regards,<br>
Kevin Lightner<br>
<br>
http://www.synthfool.com</div>
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