HR 10..attendent hum problems.attn Gareth Gammon

[Guy Giacopuzzi]

> This message bounced, so I hope you get it via the list...
>
> Some other thoughts...
> 1) This might seem elementary, so don't feel offended...does it have a three wire power
> cord, if not, make sure the chassis is grounded....
> 2) Assuming you've done the above, get a scope--I found an SO-4550 at a swap meet for
> $30--and go thru the power supply looking for AC.  Before rectification, you should see some
> nice sine waves; after, it should be rough DC; after filtering, it should look pretty good.
> Then go to the audio section with a signal tracer...you'll have to do some
> disconnecting--try to find the audio output prior to amplification and listen to it--if you
> hear hum, then it's being picked up in the audio amp somewhere....There's two stages of
> audio amp in your HR10--V6B and V4A--the audio input comes off the middle lug of the AF
> gain--disconnect this and listen with a signal tracer--you should have clean audio.  If
> there's hum, then it's not the audio amp...

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