Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: awkatche on November 02, 2020, 08:51:39 AM
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Just finished the amp last night. After a fixing a weak solder connection on B2, I powered up the amp. I noticed a loud hum in the left channel only which was present at low volumes at first. After the tubes warmed up, the hum disappeared, so I ignored and I listened to the amp for a bit without issue.
This morning, I moved the amp to my desk, powered it up and there is a constant loud hum in the left channel again, but it won't change now regardless of volume setting. I checked resistances on all of the ground connections after the potentiometer in the signal path with 12U and they were all 0. I noticed that if I tapped the 12AU7 a bit, the hum would change slightly but then came right back. I plan later today to reheat the ground connections and pretty much everything on the left channel downstream of the potentiometer, but is there anything specific connection that I should check? Is it possible that the tube is faulty?
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If you found one solder issue, it's usually a good idea to presume there are more. I would reflow all of the joints in the amp, and this shouldn't take more than about 20 mins.
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Yeah - always good advice.
Re-soldered - seems to be working fine now. Thanks again!