Xpantastic!

Karl,
I went through all the DC voltmeter measurements in the service manuel.
Everything looks good (to me) except for Step 3, +5M text.
On the right side of D4 (as I am facing the Processor Board, sometimes
I measured 6.6 v, other times I measured 3.9 to 4.9 volts.
I suspect there is a bad solder joing on D4, so I will reflow this.


> Power Supply:
> If you have a buzz in the audio output Then the power supply may be
> going. An easy way to tell is to get a new large capacitor of the
> same value and voltage . And use jumper leads to jump it across the
> suspect cap. If the buzz goes away then Replace Em. You will probobly
> not be able to find exact matches. So some retrofitting may be in
> order.

I looked at C3 and there is some dry dusty residue on the negative side of C3.
There is less residue on the negative side of C1.

These caps are old, so I might as well just replace them all at the same time.
There are 4 more electrolytic caps on the PS board, but their leads
are right up against the PCB, so I can't see if they are leaking.

> Voice 1 Problem:
> I suspect a bypass capacitor located at the output of each voice. I
> keep seeing this part failing in more and more M12/Xpanders.( mine
> included) So get a new 2.2uF 50 volt electrolytic cap. and replace
> C749 (for Voice 1). It is toward the front of the board. This same
> value part is all over the voice circuits. So.. It would not be a bad
> Idea to get a bunch of em, and replace all Cx49s. Again you gotta
> observe polarity.

I dont want to trust my baby Xpander to my shaky hands that haven't
used a soldering iron regularly since 1985, so I will have a pro do
this for me.
It will be worth the money to have all the voices re-capped.

>
> I don't know about the DAC mono test, but if you can get the voices
> to tune, then the DAC's probobly good.

In a previous email you referred to a RARE DAC. The service manual
references several whose part numbers look like easy to find
components to me.
Which rare DAC are you referring to?

Thanks


Tony