Hi Tony,
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.
You probobly know this Tony, but these caps have a polarity to them.
So you have to notice where + is and put the new one in the same
way. + to +. Also you can go higher in capacitance and voltage
ratings but not lower.
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 don't know about the DAC mono test, but if you can get the voices
to tune, then the DAC's probobly good.
Good Luck
Karl
--- In xpantastic@..., "Tony Cappellini" <cappy2112@...>
wrote:
Voice 1 seems to be bad, so I've turned it off.
With Voice 1 Off, This is the status of Autotune
VCOs- PASS
PW - PASS
RES- PASS
VCF- PASS
VCA- FAIL
(With VCO1 on, all the above tests FAIL.)
On Master Page, Page 2, Voices On.OFF, All Voices show FAIL
DAC Tests
DAC Mono- Page 2 LED blinks about 2 times per second (Is this good
or
bad? Nothing in the service manual about the blink Rate.
I hear a Buzz in the audio- which sounds like a sawtooth going
about 5
times per second.
DAC OFFSET- Page 2 LED blinks about 2 times per second. Good or bad?
All other tests on the Service Page are OK
Out of tune Points to the DAC, pray it's is not failed because
it's
even harder to find than the CEMs.
Can you tell if the filter still sweeps well? Or - Turn off the
VCO
waves and turn the resonace all the way up,and the cutoff all the
way
down, Mod by keyboard to see if you can play the filter like a
voice.
Self resonating? Yes.
Once we know if it's the DAC or
not we can go from there.
Also- after hitting untune on the DAC page, then doing auto tune, my
VCOs sound much better. In tune, that is.
So- it only looks like Voice 1 is fialing, and the VCA test.
Now what ?
