DC-3 Preamp Issues

[Orion_99]

Hello all, I am a new Mesa owner.
I have had a DC-2 for about a month and just acquired a sick DC-3. I can hear the guitar so the signal is getting through, it's just very weak. Lead and rhythm channels are both affected. I have narrowed it down to a preamp issue by running another amp into the fx return to test the output, which works fine. I also ran the DC-3 out to the other amp and I get the same results as the amp alone. All voltages are as they should be to all of the tubes. I tried known working tubes from the DC-2 with no change. All caps and resistors look to be fine. The fuse did blow while I was checking out voltages, although it was a 1 amp not 2 as it call for. It came with the DC-2, the DC-3 didn't have a fuse holder so I installed one, but I haven't been able to find any fuses locally. The fuse got quite warm which has me concerned as well.
Just looking for any suggestions of where to look next for the problem.
Thanks.

 

[dodger916]

Output tranny?

 

[Orion_99]

Thank you for your suggestion dodger, but as I mentioned in the original post the output section is working fine.

 

[Orion_99]

So after checking out the voltages again, I have found that pin one of v4, the reverb tube, is 30 volts over what it should be. Pin 6 is about 10 volts under. Also, using the "click" test, I don't get anything when I touch pin 6.
Very frustrating.

 

[ReverbIsANoun]

All voltages are as they should be to all of the tubes. I tried known working tubes from the DC-2 with no change.
Thanks.

Not much left other than PT, OT and choke, and various resistors, caps, coils. Preamp tubes are OK, but the sockets of the DC3 could be bad. Contact cleaner might do wonders for the DC3. Spray all the sockets, working each tube in and out of its socket a few times, while wet from the contact cleaner spray.

Some clown could have "modded" the amp, because, that clown had a "better" idea than Mesa Boogie. Guitar amps tend to be a magnet for self made geniuses, that aren't.

 

[Orion_99]

I figured out that it was the op amp in the recording circuit. I've ordered a new one, so we'll see if that was the only problem.
Thanks!

 

[ReverbIsANoun]

I figured out that it was the op amp in the recording circuit. I've ordered a new one, so we'll see if that was the only problem.
Thanks!

Interesting, any update?

Not one of those ubiquitous uA741 op-amp chips?

 

[Orion_99]

It was a tl072, just got the new one last week and everything works now. Gotta love a 20¢ fix.
The next thing to do is decide whether or not to keep the dc-2 and the dc-3. I kind of feel like collecting them all now.