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Subject: Re: [yamahacs80] 1 voice card not triggering. any ideas/leads? (cs80)รพ

From: rj krohn <r_j_d_2.phila@...>
Date: 2007-11-15

thanks alot for the help, kent. this is great. here's what i've got on the scope, and elsewhere:

1-w/ noise at 10, key triggers properly. so i can rule that out.

2-hp and lp filter affects noise, so i think i can rule that out.

3-VCA at 10 vs. 0 gives me a difference in gain, so i think i can rule that out.

4-i dont get any shapes at all on the scope from sine, triangle, or pwm.

so this is basically a bad VCO chip, right? now, where can i buy one of these?

thanks again kent! once i tackle this issue, i have one more little one (i think!) to take on, then its 100% working!

kent_spong <kent_spong@...> wrote: Hi RJ,

Possible causes:

Look see if the trig voltage is present at M23's TR point on the
back edge of the voice card. If it is not there, then there is a
brake in the wire from M13's TR point. If it is, then it may well be
a filter ic or the vco ic or the final vca that may be gone. If you
have a scope look and see if there is a waveform on the vca's useing
the front panel for square and sine outputs. Also check the O point
and see if the wire has come away. This is the white wire at the
bottom edge of the voice card.

Let me know how yo get on.






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