[davehanc]

Hi,
#1 is pretty well sorted. With the ground lift switched so there is no continuity between signal and amplifier grounds, there is fairly low level hum overlaid with buzz which is noticeable at low volume or between tracks, and hum/buzz increases if signal ground is touched. With ground lift unswitched, it is dead quiet.

#2 is the same with ground lift switched, but there is no output unswitched. Where should I look to fix this?

Thanks
David

[hagtech]

Wow, I can't figure this one out.  I assume you've tried swapping L & R input cables, to make sure it's not an external issue.

I guess check R25 and R30.  Not sure what else could be off.  It can get a little confusing with the mirrored channels, as many parts are not installed, depending on if left or right.

jh

[davehanc]

I did swap signal & AC cables - it's not external. Looks like the problem is R30 - #1 measures 46.5k across R25 & R30 in circuit; #2 measures 46.5k across R25 and 0 across R30. #2 R30 measures OK out of circuit, and the empty R30 points on the PCB measure 0. Any clues here?

I'll measure other differences in the vicinity between #1 & #2.

Thanks
David

[hagtech]

Could be a faulty gnd switch or solder short somewhere?  Even with R30 shorted, you should get sound.

jh