Minor buzz in right channel [resolved]

[MikeSattler]

I tightened down all the transformer hardware as well as the ground screw on the chassis last night. Used some needle nose pliers and a screwdriver so it's about as tight as it's going to ever be. I also re-soldered the pot and 9-pin socket just in case I missed a joint last time, and cleaned out all the tube pins with de-oxit but nothing has worked so far.

Just to clarify, there's 2 separate noises going on: one is a buzz in the right channel that increases with volume, and the other is a 60hz ground hum when I touch the input tube. The ground hum goes away when I touch the chassis.

I tightened down all the other socket screws and hardware just in case it was another loose screw but that didn't help either.

[Paul Birkeland]

The ground hum goes away when I touch the chassis.

Do you have 3 prong outlets in your home?  Have you put an outlet tester on them to check that the ground is actually there?

[MikeSattler]

Thanks for the help so far PB!

Yup my outlets are all grounded. I've ruled out any sort of interference or outside noise since the amp was working perfectly for years in the same room and now all of a sudden is having issues.

I went through and traced the ground connections according to Graingers sticky and had good ohm readings on all of them so I'm not sure what else to do at this point. My last guess is that the 9-pin socket may be bad so I'm going to order a replacement and solder that in to see if it fixes it. I have been doing a lot of tube rolling lately so maybe one of the pins on the adaptor wore out.

[MikeSattler]

FIXED

Wow... So it turns out the brand new Alps Blue velvet pot I bought was bad. It must have had something wrong with the ground connection in the pot since the noise never switched channels when I re-wired the pot. I ordered a new one just on a whim and installed it, and now it's fixed!

[Paul Birkeland]

These are easily damaged if they aren't paired with a small PC board that has external wire pads for the connections in the amplifier.

[MikeSattler]

Yea that makes sense, the prongs don't seem very sturdy at all. Since this is now the third Blue velvet I've had to install in here I might just make the leap to a good stepped attenuator instead.

Anyways, thanks for all the help troubleshooting!

[Deluk]

Some Blue Velvets have eyelets instead of pins. Even if you don't use the hole it gives you more surface area for a lay on joint.