trinityamps.com

hello, sIII builder here from way back. lost my account so I re-registered. no big deal. Was hoping some folks still frequented this and could answer a quick question.
troubleshooting hum on the normal side, it changes with volume; goes completely away with normal volume all the way to zero. With the volume up, I can hear it even when playing only on the TMB side. So to enjoy the tmb side I must have the vol all the way down on the normal side. If I use the Y button on my AB/Y box the hum goes silent and I can enjoy both sides. I suspect its something to do with my 47uf cap (c16). I believe its one of the bargain bin caps I got at a surplus shop. At this point knowing that my TMB side is fine, do you think I should just go ahead and swap out this cap? I was going to order one since the only other cap I have is probably close to 10 years old. Seems like there aren't that many components to look at so just wondering what someone else thinks of this.
thanks,
Don

I doubt it is the bypass cap (C16) but you could try swapping it out.

I'd be looking for loose grounds, cold solder joints, etc. Also try tube swapping, preamp tubes can cause hum. It's possible that one half of a 12AX7 can go faulty (making the TMB channel fine but the Normal channel noisey).

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http://pdfelectronics.com

yea I think thats possible, was my first and only amp build and it appeared to work perfectly on first fire up so I was proud that I was able to pull it off on first try. I should have known it would have some kind of issue over the years but now I find myself having to re-learn some things so I will definitely see if I can find something that needs cleaned up.
thanks