Bottlehead Kits > Crack-a-two-a

Hum in right channel, developed a few months in

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eudisld15:
Hello,

So it seems like my crackatwo developed a hum on the right channel. Audio volume in the right is also significantly lower as well. When I first built this kit, it passed all voltage and resistance tests at stock. I then added in some mundorf caps (100uf and 0,1uf) and it passed all tests too. About 2ish months in right channel seemingly developed a hum literally a few hours after powering it down for the night and then powering it on in the morning.

I re-ran all the tests and got significantly off results on the High Current C4S board closest to power outlet.

I went and checked all the cabling and solder, reflowed some traces/joints and replaced seemingly loose/bad cables. Returned the caps back to stock and still the voltage tests fails.
I also swapped around some tubes with 1 to 1 equivalents I had and swapped high current c4s boards. Still fails voltage test on the side closest to power inlet. Swapped 100uf cap sides. Still fails on the same side. Also checked all the traces of the low current C4S and I cannot see any bridges.

I put back the mundorf caps back on and went back to square one to mimic the day the right channel went bad and remeasured voltages, below are the results:

Low Current C4S

IA 95
OA 69
KRegA 0.344
bRegA 97.7

IB 199.4
OB 66.3
KregB 17.4
bRegB 199.4

High current C4S (closest to power inlet)

IA 201
OA 199
bA 0
IB 0
OB 110
bB 199


High Current C4S (furthest from power inlet)

IA 196
OA 97
bA 0
IB 0
OB 74
bB 96

Does anyone have any Idea on where to start checking for defects again?

eudisld15:
For some reason when I try to upload images the site times out, here's a Google drive folder with pictures

https://drive.google.com/folderview?id=1qOeSiA1fVzfX006OrQuOrESk5sGNLn6J

Paul Birkeland:
Neither channel is working properly. Both have unique issues.  I would suspect loose connections or broken wires that got disturbed when you parts swapped.

Paul Birkeland:
I hate to say this, but you make a huge gamble putting in sockets like that.  I used to do a ton of kit repairs where I would pull out fancy sockets from people's kits and put our sockets in to get them working properly. It got so common and tedious that we disqualified kits with different sockets from our repair services entirely. 

eudisld15:
Only the two center tubes have the fancy sockets. Do you recommend I swap it back to the stock ones first. I don't mind doing it tonight.

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