Studio 22+ Bass Control Not Working

[selectortone]

Hi, this is my first post (long time lurker) so firstly I'd like to say "Hello!" and thanks to the mods for providing such a great resource for Mesa-Boogie owners.

I'm a long-time DC-5 owner, been gigging with mine for over 15 years and absolutely love it to death.

I recently purchased a 22+ which I'm hoping I can use for the smaller gigs my band plays and give my poor old back a rest.

The amp is in great condition and everything is working except the bass control which does nothing.

I'm OK with working on my amps and I have a schematic but on taking the chassis out of the cab I'm wondering how on earth I can get at the component side of the board without unsoldering half the connections. The pot checks out OK btw so I'm guessing the problem is somewhere around C8.

If anyone can tell me the least painful way to get at the component side of the PCB I'd be very grateful!

Thanks in advance

 

[selectortone]

C41 was short-circuit.

Not too difficult, the way to do it is to undo all the pots then the board lifts right up.

I thought I'd better post that, cos I knew by the volume of replies that you were all on the edges of your seats :wink:

I LOVE this little combo. Now the tone stack is working properly it sounds fantastic.

 

[selectortone]

I was finding the lead channel just a bit too overdriven so I tried the Lead Drive mod. WOW! It adds a whole new level of controllability to the lead channel.

I notice that the coupling cap from V1 to V2 is .001uf. The Lead Drive mod is basically just adding the lead drive pot that's in the later Mark amps - I'm thinking it might be interesting to try a .047uf in there, as used in those amps. As is, the 22+ lead channel is quite toppy/thin sounding, a .047 would in theory fatten up the sound a lot. If it sounds OK I could put it on a push/pull.

Has anybody tried this? Is there anybody out there? :wink:

This is a cool little amp.

 

[Monsta-Tone]

That should work. If the .047 is too muddy or thick, you could try a .003 or even a .002.

Congrats on removing the board. Luckily they only did this with a few models. Most of their amps have the components on the top of the board where they are easy to get to.