RE: Odd hum issue - suggestions ?? - rogerh113

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RE: Odd hum issue - suggestions ??

Posted by rogerh113 (A) on May 31, 2017 at 17:31:41

In Reply to: Odd hum issue - suggestions ?? posted by rogerh113 on May 30, 2017 at 15:41:04:

Yes. My limited understand is that the signal ground (neutral) is best only connected to the ground in one spot. I gather to avoid ground loops, etc. There is an existing connection going from the neutral on the main board to a lug on the chassis at the rear of the amp. I removed it and then checked the resistance between the board neutral and chassis (ground) and it was infinite (no second connection).

As it turns out, the problem seems to have been fixed by connecting the signal ground (netural) at the big power caps to the chassis. I tried connecting the ground lug to the board neutral with a large jumper (assume the wire inadequate to handle the 'load'. No reduction of hum. Connected the main board netural lug directly to the ground lug at the front of the amp where the ground wire is attached - no improvement. Connecting the large cap neutrals to the chassis just eliminated the hum. The wires from the cap neutral lugs to the main board neutral are quite large, so it does not seem they are deficient and were causing the problem.

Hooked up a signal generator, and both sides seem to be working nicely, especially without the hum to get in the way. Just need to calibrate the amplifier boards, and hopefully will be ready to go.

Thanks very much for the tips and suggestions. A bit of support really helps when tackling a problem that seems to be somewhat obscure at times..

regards -- Roger

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Follow Ups Full Thread

Topic - Odd hum issue - suggestions ?? - rogerh113 15:41:04 05/30/17 (13)

RE: Odd hum issue - suggestions ?? - rogerh113 17:31:41 05/31/17 (2)

A couple of suggestions - Ralph 11:00:42 06/02/17 (1)

THAT sophisticated method is way cool, Ralph... Thank You~nT - Cleantimestream 14:23:14 06/02/17 (0)

RE: Odd hum issue - suggestions ?? - Triode_Kingdom 15:59:58 05/30/17 (9)

RE: Odd hum issue - suggestions ?? - rogerh113 16:28:22 05/30/17 (8)

RE: Odd hum issue - suggestions ?? - rogerh113 08:35:42 05/31/17 (3)

RE: Odd hum issue - suggestions ?? - Tre' 09:30:02 05/31/17 (1)

RE: Odd hum issue - suggestions ?? - jwu - snoopy.org 13:47:24 08/23/20 (0)

RE: Odd hum issue - suggestions ?? - Triode_Kingdom 09:10:33 05/31/17 (0)

RE: Odd hum issue - suggestions ?? - Triode_Kingdom 06:41:04 05/31/17 (0)

RE: Odd hum issue - suggestions ?? - Chip647 18:54:59 05/30/17 (2)

RE: Odd hum issue - suggestions ?? - FenderLover 21:52:35 05/30/17 (1)

RE: Odd hum issue - suggestions ?? - Frihed89 02:06:23 05/31/17 (0)

Follow Ups

RE: Odd hum issue - suggestions ?? - rogerh113 17:31:41 05/31/17 (2)

A couple of suggestions - Ralph 11:00:42 06/02/17 (1)

THAT sophisticated method is way cool, Ralph... Thank You~nT - Cleantimestream 14:23:14 06/02/17 (0)

RE: Odd hum issue - suggestions ??

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