Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Platefire on June 07, 2013, 11:33:08 pm
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I finally been accepting PCB board amps in for repair with the understanding I may or may not be able to do some good.
This Stealth-50 is the first amp with 4-6V6's that I've seen up close. Also has 3-12AX7's in the preamp section. The customer said it was loosing power and demonstrated it playing through it and got it to go in and out once. I got it home and chop sticked it live in its low volume mode and after about 30 minets when I touched the effects loop return jack it kicked in. Cleaned the jack with contact cleaner and it's purring like a kitten now.
The thing sounds pretty good but has a little edgy harshnes to it that can't seemed to be dialed out completly. It has a clean and a drive channel and the drive channel has two levels of gain. So with the footswitch hooked up you can get clean, crunch and lead. Not bad! Glad it was an easy fix! :icon_biggrin: Plate
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That has to be the number one culprit with amps that have effects loops and are cutting out.
Good job!
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"That has to be the number one culprit with amps that have effects loops and are cutting out. "
Quite agreed. Hate those plastic 1/4" jacks, and on inputs, too. Just asking for trouble.
By the time you have a big heavy Neutrik male 1/4" plug and big heavy wire, the leverage you have pulling sideways on those plastic connectors is trouble waiting to happen.
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I worked on a Laney Head a while back that the 10 wire connector from the main board to the effects board and was cutting out where it connected to the effects board. I disconnected it and sprayed contact cleaner on the pins/sockets worked it up and down a couple of times. It worked for about a day. I disconnected the connector and gave it an even more complete cleaning. I tested it powering on and off over a period of days many times with no failure so gave it back to the customer. He latter called me and said it worked for a couple of hours of continuous playing and went out again.
I told him he needed to take it to a service center who can service that amp. I didn't want to get into pulling boards, changing connectors and what ever goes along with it. I did locate the problem and had a schematic I got off the net with the faulty connection highlighted for what ever tech to get jump started on it. Maybe someday I would dive in but as of right now I'm too unfamiliar. I'll keep pluggen on them though. Plate