Dual Rectifier 2ch Volume Drop Red Channel

[TeeWX]

Hey everyone,

I just picked up a used Dual Rec online from Guitar Center, and unfortunately it's got a problem and I'm trying to determine the severity/easy of repair. It's an older 2 Channel Rectifier. Here's what happens...

When I start the amp up from cold I can play on it for roughly 5-10 minutes before the Red Channel instantly loses 90% of it's volume and low end power. The Orange Channel still seems to work just fine, however. If I clone the Orange Channel to be the Red Channel it also seems to work.

From my research it sounds like there may be faulty LDR's (Light-Dependent Resistors) within the amp. Does this sound accurate? I don't believe I have any techs nearby as I live in a relatively remote area. I am pretty hand with a soldering iron though. Are these parts relatively easy to replace? I couldn't find any information regarding the value's needed or where to get them. Does anyone know? I was going to ask the company for a refund and then attempt a fix. Otherwise I would be returning it.

Thanks in advance!

 

[JCDenton6]

Sounds like an LDR problem to me.
They are a little bit of a pain to swap out due to being in cramped parts of the board but if you're used to soldering in said conditions I think you will be fine.
Watch out for the thinner than normal traces along the LDRs, easy to lift.

I think it's a best bet to swap out all the LDRs to be on the safe side to prevent future failures.

 

[TeeWX]

Sounds like an LDR problem to me.
They are a little bit of a pain to swap out due to being in cramped parts of the board but if you're used to soldering in said conditions I think you will be fine.
Watch out for the thinner than normal traces along the LDRs, easy to lift.

I think it's a best bet to swap out all the LDRs to be on the safe side to prevent future failures.

Thanks for the response! Do you know which LDR's the Dual Rectifier requires and/or where to get them?

Thanks!

 

[JCDenton6]

Mesa uses "5C9" type LDRs throughout most of the amp but use a "5C4/2" type for LDR3 and "5C2" type for LDR 10
The full designation would look like "VTL5C9, VTL5C4/2 and VTL5C2 stamped on the LDR itself.

You can get the parts from Mesa itself, shoot them a call and tell them you have a 2 ch DR with faulty LDRs.
If not, try Mouser or Amplified Parts.