Deluxe Reverb tube problem

[Alexandre IV]

Hi everyone,

I have a Deluxe Reverb with the following problem: the power light is very dim, almost totally off. I know it means I need to change some of the tubes, but which ones?

It would be useful to have a full description of how to troubleshoot tubes on a Deluxe, after all, there are 9 tubes on this freakin amp!

Thanks,

Alex

[Enzo]

Power light means tube change? That's a new on on me. The power light is just a light. All it does is tell you the amp is turned on. Unscrew the jewel and flick the bulb with your fingernail and it will probably brighten up.

Is there some performance deficit you are suffering? Or is it just the light? If the amp sounds good, then it is good. Light or no light. If it is doing something wrong, we can help.

We troubleshoot tubes on a Deluxe same as any other amp: by the symptom. RG has some excellent troubleshooting guides on his Geofex site. And there are numerous books on servicing your own amps. Amps all work the same, we use the same procedures for all.

[Alexandre IV]

Hi Enzo,

Thanks. You were right about the light. But here are a few symptoms I've noticed last time I used the amp. About halfway into a 2 hour set, it started feeding, like a high pitched sound but I had no fuzz going whatsoever. Guitar straight in the amp, no pedals, and the high pitched countinuous note coming out of the amp. That can't be good, right?

I will get one of the books you mentionned, but in the meantime, I have a gig tonight so I'm hoping I can be prepared if something sounds funny,

Thanks,

A

[Mars Amp Repair]

an easy way to determine if the symptom is a tube or not is to pull off the shields on all the 12AX7's & 12AT7's & just tap the tubes with the handle end of a smaller screwdriver.
If the screaming or whatever you're hearing stops or gets worse...replacing that tube is a good place to start.
Swapping one of the other same type tubes with the one that is making noise will save you having to buy the tube before you know if it's really causing the problem.

A noisey 12AT7 or 12AX7 tube when put in the in the driver postion (usually closest to the power tubes) will usually not cause as much an issue as being in one of the higher gain posiitons, so swapping your noisey tube with that one can help in troubleshooting without initially buying any tubes.
For this test purpose, you can swap the 12AT's & the 12AX7's...just be certain you get them right when you finally determine which one (if any) is bad....glen

[Mars Amp Repair]

OOOPs, almost forgot.
A tube with tarnished pins can also cause big noise problems & make you think you have a bad tube socket. Slightly burnising the pins & spraying them with some contact cleaner can solve this issue. If you actually have a tarnished tube socket pins, this method can also clean them up by working the burnished tube in & out of the socket a few times. glen

[stokes]

As well as the suggestions from Glen,if you are experiencing the squeel with the reverb on,try turning it down to see if the squeel goes away,this will tell you it is related to the reverb circuit,commonly a tube problem.

[Enzo]

Here is the first test: when it starts squealing, turn the volume on the guitar down to zero. Does the noise stop? If not, then the tubes might be microphonic. But if the guitar can turn off the noise, I'd bet on the guitar being at fault. And like stokes says, turn the reverb down to see if it is involved.

You can take the shields off the tubes and whack them, I do it often enough, but usually I leave them on. I reach in the hole at the top of the shield with a fingertip, and flick the little glass pointback and forth with my fingernail. That usually exposes microphonic tubes.