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<p>Hi,</p>
<p>Check the buffer transistor. That had blown on mine.</p>
<p>The Mark II PSU is nicer than the Mark I PSU for VCS3/Synthi-A.</p>
<p>About the same time as the Mark I and Mark II shift, they moved
the transistors off the PSU board. If they are on the board, move
them out as this remove heat and it will eventually fail. Guess
how I know.<br>
</p>
<p>Cheers,<br>
Magnus<br>
</p>
<div class="moz-cite-prefix">On 2022-09-13 21:50, Mattias
Rickardsson wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAP92RBWzvSMJ_gGkaYpsNobRzGO7jDJgp9UA3x6Z8sw0_grcVw@mail.gmail.com">
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<div dir="auto">Hey,
<div dir="auto"><br>
<div dir="auto">I'm trying to revive a VCS3 II where the power
supply has issues on the negative regulation. With an
incoming -25 V it puts out roughly -24 V instead of the
supposed -9 V. Does anyone have experience with similar
problems?</div>
<div dir="auto"><br>
</div>
<div dir="auto">(The transformer was fried on the negative
half, so I'm running it from a bench supply. I have also
replaced the regulating 741 and TIP3055 power transistor)</div>
<div dir="auto"><br>
</div>
<div dir="auto">((The <a href="http://phutney.com"
moz-do-not-send="true">phutney.com</a> site and its very
readable schematics also magically disappeared, which didn't
help)) :-)</div>
<div dir="auto"><br>
</div>
<div dir="auto">Best,</div>
<div dir="auto"><br>
</div>
<div dir="auto">/mr</div>
<div dir="auto"><br>
</div>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
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