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Based on the schematics, - 47vdc for the outer and - 56vdc for inner (470 plate resistors). I'm assuming that's for both versions but the tube layout may be different in version two. The tubes with the 2.7k' s plate resistors are the lower voltage (-47). But there is a general tolerance usually...

I understand your frustration. That's the only schematic that I could find. I don't understand why Mesa is so notorious for their un readable schematics. P!us lots of errors in them. Techs at times need to be able to understand what they look at. I completely traced my 2:90 out. To my amazement...

Try this. http://guiguijones.free.fr/Electronique & Bouine/electronique/Schema Amplis Effets etc/Amplis/Mesa Boogie/mesa.htm . Mesa is notorious for hiding the component numbers on board. I had to do lots of tracing in my 2:90.

Ty BoogieBabies. I've been searching forever about that. Blessings. Jim

You're welcome. I'm happy I helped. :)

That's great news! I hope it solved your issue brother. Blessings. Jim

You're welcome. No. The signal goes through the input tube then to the PI tubes , then to the power tubes. And yes, roll the 12ax7's to see if it helps. Some preamp tubes may glow brighter than others. Just as long as they glow. When you said power imbalance, are you suggesting that one channel...

If rolling power tubes doesn't help, you may have to open it up . There are high voltage levels inside. If you don't feel comfortable, take it to someone. I would start with the 12xa7's inside for the PI of each channel. Not so much the input tube. But it cant be ruled out though.Then go from there.

Ty for more picts. I was gonna suggest that you get some gut shots too. From what I can tell, the inside looks fairly good . Clean. It has a combo of metal oxide and carbon comp resistors on the screen grids. No biggy. Carbon comp has a reputation of being just a bit more noisy. And that white...

Greetings. Pm me. I've had a 2:90 , first version since 1994. Thats what this one appears to be. I apologize but I don't have time to answer currently.

What does the 120pf cap do in the older C+'s in the effects loop ( connected to cathode to grid on V2A )? My schematic says they were removed after August 1984. My DRG C+ still has it . will someone please explain its purpose and why it was removed? Thank you for your time.

Some ppl I heard just remove the 1 amp fuse of unused channel. I think it just keeps it in stand by. Not sure if this is healthy for transformers though. Cheers and blessings. Jim

Greetings. So is there a fix for the dreaded popping noise with half drive or not? If not, shame on Mesa. That pop is unacceptable.

Ty for the reply. When engaging half drive I get a loud snap sound. Different on other channel. I understand that there's always a little popping sound. Been that way for years.Those LDR's were supposed to have taken care of that. This just recently started. I've been troubleshooting my *** off...

Greetings. Are there any tech/ 2:90 experts in the house? Ty!

That's exactly what I did. And boy, you are so right about their schematics. Tho the one for the 2:90 is really close. But for my C+, wow! Rediculous! From factory. I did find a decent one here in this forum where someone took some time and traced everything out.

Ok. I have the app. I'll add number. Do you need my number? I kinda echo Dan. If you are not 100% certain you can do this, take it to a tech. But since you have some experience working on amps, its your call. Yes. One channel at a time but when powered up, both channels are on. As mentioned, its...

I do not know anything about that app. That's where i'll need your help. First, get components that you wish to replace. I just looked at my LDR's that I replaced hoping for a crossover part number that you can get there but they basically said the same thing on them . The LDR part number on my...

Ty. I completely overlooked that.