Got a fender blues deville mexican, fixed a few problems but reverb feedsback bad.

[Corben]

Ok well originally i opened it up and found that the first preamp tube socket had been retightend so many times i just thought id replace it. SO i did. Then i found where another tech didn't have the correct 91k 1/2watt resistor and so used four series parallel resistors to make up for it. This cause some poor solder joints and anytime the amp vibrated or when i gave it the rubber mallet test it would distort and cut in and out. So i replaced it. Then i noticed that those terrible little ribbon-wire connectors that go to the tube board from the main board all had broken solder contacts on it so i repaired or replaced those and put some silicone glue on it so it wouldn't break as quick next time. Then i found some lose wires that were the crimp on type on the main board that were lose and would do the same thing during vibrations. SO i solderd those on.

After all this i thought well i better make certain that Ive found all these bad connections. SO i took my rubber mallet and one step above gently tapped about the amp cabinet the chassis and lightly with a piece of wood on the circuit boards. All of a sudden the reverb started to feed back hardcore i believe it started squealing incredibly after a tap on the left side of the chassis. Now if i turn the reverb control up it causes the amp to get quite if the tank is not connected. I tried checking for mechanical causes to the feedback by removing the tank from the cabinet. Then hooked up a spare tank and the hard feedback squeal was still there so i believe it to be somewhere in the reverb circuitry.

I'm stuck at this point and have put so much time into repairing this amp i could use some help. Thanks guys.

[stokes]

I would try a different tube for the reverb first,no,first I would stop whacking it with a hammer.There was a tech bulletin I read on either this or the blues deluxe,forget which,but they are all basically the same construction.Anyway,a cause of HF oscillation in these amps is sometimes caused by one of the ribbon cables merely being bent in a fashion that causes an oscillation,I doubt this is your problem,but you never know.

[Corben]

no reverb tube in this buddy. its solid state reverb circuitry, oh and if it cant take a weak bump from a rubber mallet it def can not take years of gigging. So board failure from slight bumps is a prob in need of resolving until it doesnt continue.