Express 5:50 5W Mode Quiet and Distorted

[Wrm708]

Recently picked up an Express 5:50 (not the plus model) and noticed that it was having issues on the 5 watt mode. 50 watts sounds fine, but on 5 watts it is way too quiet and distorted even on the clean mode. Again, this is not an issue with 50 watts.

I suspected a preamp tube and have swapped out others to test with no success. I then picked up a matched pair of Mesa 6L6 GCs and, while the 50 watt mode sounds great now, the same issue with the 5 watt is still with issues.

I’m pretty handy with soldering and other simple repairs, so if anyone has any suggestions on caps, resistors, etc to check, I’d really appreciate it. Thanks in advance.

Wes

 

[DrKev]

Email Mesa and give them your serial number. They can send you the appropriate schematic and maybe give you advice on what to check. The power section itself isn't too complicated but finding/accessing the components may be some work.

 

[Wrm708]

Email Mesa and give them your serial number. They can send you the appropriate schematic and maybe give you advice on what to check. The power section itself isn't too complicated but finding/accessing the components may be some work.

Thanks! Email sent.

 

[Wrm708]

So Mesa was no help. Just said send it to a service tech or them. Would really like to sort this on my own if it’s not too difficult. Again, reasonable experience with soldering and replacing caps etc. Anyone else have thoughts on where to start?

 

[DrKev]

Send me private message here with your email address and I'll email the schematic I have to you. I'd start by verifying the voltages. That will help you figure out what part of teh circuit to look at,.

 

[Rawkenstein]

was this problem ever solved ? I have the same problem. I don't plan on using 5 watt mode but I don't like the ideal of it not working 100%. I fix about 20-30 amps a year but would not call myself anywhere near as proficient as I would like to be. always learning.

 

[shawnohio]

was this problem ever solved ? I have the same problem. I don't plan on using 5 watt mode but I don't like the ideal of it not working 100%. I fix about 20-30 amps a year but would not call myself anywhere near as proficient as I would like to be. always learning.

just swap out all the preamp tubes. spray the switch also.

 

[Rawkenstein]

Well , found the problem. Resoldered it and like new!