Hot Rod Deville, reverb squeal...

modding the reverb takes some electronics experience...if you know where the reverb circuit is. all you can really do is change the input caps that make the tone bright or dull... larger uf for dull... lower cap values for bright... it's in the signal circuits... dont mess with power caps. The schematic shows op amp into the tank and out of the tank to another op amp...Output of the tank to opamp.. Id double that input cap ( 330 pf ) to see if you get more response into the opamp... then look at the circuit C17-C18/R33-R34

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/lisa_52daba487e5b4d53

change out pre amp tubes

Hi. If the volume and drive levels are considerably low but you still hear a noise, you may want to consider trying a different guitar cable. The noise may be coming from a ground loop which is being amplified and overdriven by the amp itseld. I hope this helps. :-)

Your reverb spring is most likely broken. If it has electronic reverb, then the chip has gone out. For both of these problems, a qualified amplifier technician will have to look at it and replace the parts.


Hope that helps!

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/cameron_463100ffd54b591d

Without more info can't be much help. IF you are using the foot switch, poor contact of the plug AND also of the switch contacts of the footswitch jack will lead to intermittent reverb. There are MANY components that can cause the problem, including some may be temp sensitive... you need to characterize what MIGHT be changing in the environment. Also does vibrating the unit cause any change? You could even have a loose connection or bad cables that goes to the reverb tank...
This may take electronic test equipment to find the cause. COuld be failing component, crack on the circuit board, bad connector, cable...

First check if the reverb "tank cables" are on tighly where they attach.

probably a bad reverb tank. there is a little inductor inside that shorts out easily/common. you cant repair it. its just easier to order a new tank. what you do to test is........turn on the amp with the reverb turned up all the way........ volume up on the amp at normal playing level.....then tap or knock on the reverb tank itself......if you get sound then the output of the tank is good/ no sound the ouput side is dead.......then what you do is unplug the ouput of the tank and plug the output wire to the input of the tank and tap/knock on it again....if you get sound then the input side of the tank is good/ no sound is dead. this is a way to test the tank independently from input to output. which side is bad is irrelevant, what is improtant is determining if the tank is toast. i can get accutronics tanks from my distributor at a better price than anywhere else. email me thru my contact page on my website with the tank code numbers and letters so i can get you a price also check my price with whats on ebay, etc. my website is yostamplifier.com
good luck

It sounds like a filter capacitor(s) has failed. The electrolytic caps dry out and cease to perform allowing unfiltered power to reach the preamp sections and get amplified.

Being this is tube with high voltages, an experienced person should work on it due to shock danger.

I assume you checked the tubes for shorts as well as emission since a heater to cathode short could cause this as well.

Try this article first for some ideas. http://www.guitarplayer.com/article/reverb-troubleshooting/jun-09/97165.