M-Audio AV30 V2.0

[Greg Green]

Looking for M-Audio AV30 V2.0 schematic. Have V3.0 did the Z1 thing and filter caps. Has loss of left channel signal from input to pin 2 U2 quad op amp. V2.0 has U1 4558C dual op amp that V3.0 doesn't have. Any help would be greatly appreciated.
Greg Green

[Jazz P Bass]

When checking an opamp, it is best to look at the output pin.
Not sure how you checked it.
Opamp input pins are sometimes 'unreadable'. (virtual ground something or other)

[Greg Green]

Yes, I understand your statement. There is no left channel output, however I could touch the input pins with a screw driver and get a hum, fairly equal from both channels. So everything is passive going to the input of the op amp. With the power off to the amp, I had my HP sine wave generator on and had readable signal to pin 6 right channel of U2 and nothing at pin 2 left channel. I haven't gotten more to the point to point circuit tracing, but the board isn't exactly as on the ver. 3 print that I am using. That is why I was trying to get a ver. 2 print. With power on, my scope won't show a signal at the highest sensitivity of .01 volt.