Studio .22+ with EQ volume drop problems

[javimm]

Hi. First time poster here.

I bought a Studio .22+ with graphic EQ about 5-8 years ago, and retubed it inmediately as the tubes were very old upon inspection. I bought a set of JJ tubes from Eurotubes, and the amp has worked great untill the other day. After half an hour of playing, the volume suddenly drops to very low volumes after a very subtle noise. It happens in both channels. The sound still retains its character, it just drops in volume and then it recovers. After several seconds volume drops again. This happens playing straight to the amp, no pedals and nothing in the FX loop. I thought of retubing the amp, as the tubes are now a bit old, but the amp hasn't seen much use. Just about an hour or so every three weeks and always at bedroom levels.

I don't know what the problem can be. I've been researching for this problem and I've read about recap works, LDR replacement (BTW, what's a LDR?), resistor change, open solder joints and tons of other things.

I think I'm going to change all my tubes and try if it fixes the problem, but I think the tubes should have lasted a little longer looking at the little use they've seen.

Any ideas of what could be the problem?.

Thank you very much.

 

[Bob Anthony]

Take a patch cord and plug it into the effects loop-The signal goes through it otherwise. It's a chronic problem with this model, and this does take care of it.

 

[JimAnsell]

clean the fx loop jacks.
it happens to pretty much all amps with an fx loop at some point.
IT DOESN'T MATTER IF YOU USE THE LOOP OR NOT!

also clean all the pots while you're at it.

 

[Bob Anthony]

Jim, e-shouting is not necessary--I have seen the plugging of the effects loop as a solution to the volume drop listed many times on this site, and it did work for me and obviously many others. Of course you are correct about cleaning the jacks, so I appreciate you pointing out that this is a problem with most channel-switch amps (It rendered my Fender Blues DeVille nearly unplayable). Not being a channel-switch guy as a rule (Studio .22 excepted), this is good to know. I really like these amps for their versatility and portability.

 

[javimm]

Thanks for the great tips. I'll buy some kind of contact cleaner. It's good to know that maybe the solution is that easy.

 

[texmexboogie]

Power tubes can do that. Put the old ones in and test it

 

[Tacoiardul]

today ,on the lead channel only,my 22+ had big volume drops when playing.the clean channel wasn't at all affected.on the lead channel the volume suddenly dropped and the sound became fuzzy and thin.i checked the tubes and the first tube,V1,was glowing less then the other tubes.i suspect it's broken,am i right?this is my very first tube amp so i am kinda still learning thank you very much

 

[MissingLinkWray]

After 4 years with this problem and $100s in shop costs, this is the first time I've ever heard about the patch cord solution. So far it has worked. It'd be a great thing if it is the solution to my problem because I was just about ready to blow a grand on a new amp.

 

[>Photi G<]

Someone said something about LDR replacement? That is usually unnecessary. LDR's don't usually go bad, since they're solid-state devices. If your amp doesn't switch channels, then we have an LDR problem. It usually isn't the case though.

Oh, and BTW, LDR's are Light Dependent Resistors, but as used in Boogies, their true names are Infrared Optocouplers. Basically the SS equivalent of a Relay. They are usually used for channel switching because relays were found to make popping noises when switching.

 

[trackerdan]

It's to bad that Mesa does not have a list of issues and fixes for their amps on their website. Mesa's phone customer service is second to none in my book but as time goes by their techs get younger and they haven't had the full exposure to the many amps Mesa has crafted over the years. I was speaking with a tech the other day and he was able to get to another support person who was able to give him the right information for me. But that was a fairly unique incident I felt.

If it wasn't for finding this website I'd be up **** creek for resources.

Thank you Boogie Board members.

TD