Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: eojcam on May 07, 2012, 03:22:37 pm
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hi, new guy here with a little old 3 tube epi pacemaker w/tremolo that is making
weird popping and sputtering sounds with volume turned off.
tubes are a j.a.n. 5y3 rectifier, GE 6BM8/ECL82 power tube, and a sovtech 12AX7
in the pre amp.
i've opened it up and with power on tapped the handful of components with a chopstick
and there is a noise produced when the cap/resistor combination over the rectifier's socket
is tapped. no noise is produced when other components are tapped. amp is working, but too noisy.
i replaced the original 3 cap can with new individual caps a year ago.
the rectifier's tube socket is a little wobbly, and wiggling the tube while powered up also produces
some noise.
serial no. is 111024.
2 input jacks, only two knobs, volume and tremolo(tremolo pot is an on/off.) a fuse, and red pilot light round out front panel features.
amp is marked model 50T, but other posts show a different amp altogether.
any suggestions for getting this amp in top condition?
thanks in advance
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i think you answered your own question. the popping sound is there when you wiggle the rectifier. or when you hit components related to the rectifier (and probably wired directly to that tube socket?)
sounds like it's time to re-tension or replace that socket.
do you have a scope? or maybe an analog voltage meter with a needle? if you hook them up to the rectifier and wiggle it you can probably see the pops coming from there. (a digital meter doesn't react very fast)
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Hey Joe! I heard you shot your pacemaker down. Glad you found the problem. Joe's a great guy with a lot of patience.
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i did retention the tube sockets, and she's purring like a Jaguar,
screaming like a banshee.
thanks to all who responded.
Can anyone advise and/or guide me through removal of the
2-proncg ac line and installation of a grounded 3-prong, please?
thanks
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Check out this website. http://www.theguitarfiles.com/guitarfile644.html (http://www.theguitarfiles.com/guitarfile644.html)
Take the warning at the beginning seriously.
If you only know 23 letters of the alphabet, or partner only knows 23 letters of the alphabet then tread carefully (The missing letters are C P R).
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Check out this website. http://www.theguitarfiles.com/guitarfile644.html (http://www.theguitarfiles.com/guitarfile644.html)
If the neutral (white) wire were fused, should the fuse blow, you would still have lots of current, only it would travel through the green wire, not the white. Best have both fuse and switch on the hot (black-wire) leg.
No problem as long as the venue you're playing is wired to code.
IF it is shorting to ground before the fuse and the return to "neutral" ground, that fuse will fail to help to begin with in the neutral line with Ground present. Same if it is moved to the hot line, and between the breaker panel and the outlet the hot and return are reversed: the fuse AND switch will make no difference. In either case, that leaves you with the last, or near last line of defense: the breakers in the breaker panel, and/or the fuse in the power cord (if fused.)
As per the warning... you might not see 500VD, you may see more in some amps, and in most others less... Doesn't matter. Some people have serious problems at 120VAC, and others not show serious problems until 230VAC (+/- 10V)... DCV is worse because it doesn't "pulse" like that (especially after filtering, also 100/120Hz pulses are even worse than 60Hz for letting go.) Also, a single high voltage and current pulse is enough to stop a heart (A charged cap can do just that.) Why risk serious injury or even death? HEED the Warning.
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Urban myth time.
About a half a century ago, I was told by an electrical engineering student, that power contained in a AA battery was sufficient to stop the heart. Base conditions, fingers pricked on each hand, so bleeding is present, and then short out the battery. If the heart is at the right place, your heart goes into fibrillation.
Heed the warnings, the person who finds you might not know all the letters of the English alphabet.
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BS!
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Pick on amp name time.
Is it safe to play that 'Pacemaker' In the kitchen while warming up nachos in the MW, or worse around Sluckey's radar? :laugh: :laugh: (See next post, Sluckey got serf'd to Stuckey, I just sanserf'd )
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Stuckey's doesn't have a radar. But they have some nice pecan pralines.