Studio 22+ Help / advice please...

[rheilman]

Hi, I recently got a hand-me down studio 22. The only problem is that it does not function correctly (probably the only reason i got it in the first place).

When I turn it on, it does play, but only at a fraction of the volume that it should have. All of the controls seem to function, including the reverb. There is not any obvious humming or strange noises, leading me to believe that the caps are ok, but i dont know for sure.

When i plug into the back, in the effects return jack, the amp plays significantly louder than when i plug into the front. this leads me to believe that there is a problem in the pre-amp section, rather than the power amp.

So far i have changed the tubes out with various other el84's and 12ax7's. I have cleaned all of the jacks and pots. I have visually inspected the circuit board for broken solder joints or other obvious problems. There were none other than some slight oxidation on some of the solder traces, which i dont think are severe enough to cause a problem.

I have a mild amount of electronics experience, access to a voltmeter/ohmmeter, and a schematic for the circuit that i pulled from online.

Any suggestion as to what components i should focus on, or general advice as to how to get this amp up and running would be much appreciated.

Thanks
Ray

 

[killerburst]

Sounds like a bad/dirty FX loop jack. Connect a short cable from the FX send to the FX return and see if that solves your problem.

 

[disassembled]

If the above suggestion for the effects loop does not work you should try removing the preamp tubes and placing them in different slots. Better yet, if you can replace all the preamp tubes with known good ones that would help on cutting down time to troubleshoot.


Good luck. Sounds like an easy fix.

Greg

 

[rheilman]

Killerburst, you are my hero!. The amp works fine now, and it sounds great, despite the cheap *** tubes i have in it. Sounds so much better than my other amp (peavy classic 30).

many many thanks! especially since you saved me the 40 bucks to have the amp dude look at it.

I guess i will try to clean those jacks, and replace them if that dosent work.

Peace
Ray

 

[killerburst]

Glad I was of some help.

Killerburst, you are my hero!. The amp works fine now, and it sounds great, despite the cheap *** tubes i have in it. Sounds so much better than my other amp (peavy classic 30).

many many thanks! especially since you saved me the 40 bucks to have the amp dude look at it.

I guess i will try to clean those jacks, and replace them if that dosent work.

Peace
Ray

 

[madvek22]

I have a similar problem with my studio .22+. Mine does not have the GEQ. I recently picked up an EQ pedal and pur it in the effects loop, first time I used the loop. The EQ did sound great, marked improvement. However, I started getting the volume drop problem mentioned above at the first gig I used it with the EQ. Pulled the EQ out and the problem went away. I guess the easy solution would be to just give up on the loop and put the EQ in front of the input. Any other suggestions ?