Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Rockranger on March 19, 2020, 06:00:40 am
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Bought a tube depot 5E3 Kit 4 years ago (my first amp build). Worked pretty good but after a while it took longer and longer warm up time to get sound out of it. You can hear the hum of the amp when you flip the standby switch on but no sound from the guitar, until like 20-30 mins warm up! The project was my first and pretty messy inside so after several successful amp builds over the last few years I decided to redo this one. Brand new hand wired board instead of pcb style board that was in it, all new wiring, and new on/off and standby switches. Everything looked great and worked perfectly right away, then after about 2 weeks I began having the exact same problem as before, if anyone has any suggestions as to what the problem may be, it would be greatly appreciated!
Thanks
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Tubes?
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Everything except for V2 is new
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Record all voltages ,power supply nodes and all tube pins, while the amp is working. Then repeat when the amp is not working. Post results.
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Alright thanks sluckey
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I'm guessing it has to do with heat; a bad connection somwhere which makes contact as it heats up and things start to expand. As it's probably not something on the board or the tubes, suspects would be tube sockets, jacks and pots and any off-board components.
I'd start by poking around inside the chassis with a chopstick while the amp is warming up (and not working) to see if you find a glitchy connection somewhere. (All the usual safety precautions should be observed of course...)
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The amp was already warmed up yesterday when I posted the problem, noticed that the normal channel (which I never use) seemed to be working fine, reflowed all the solder in the pre amp and tube sockets. Everything is now working fine again, all my voltages are matching when I first built the amp and it was working fine and look good compared to the suggested voltages on robrobs webpage. I fixed the problem before I could get any readings when it was not working. d95err is correct I guess the problem here is heat (it is the hottest amp I own), it is the only thing the old build and the new build have in common. Thanks guys!