A list of problems with my Dual Rectifier...

[Botch]

Hi guys. Well as the title states I have a list of things that are wrong with my amp (it's the 2 channel version). If you could shed any light on them it would be great. Here we go...

a) The channel footswitching doesn't work. I tried switching channels via the back to check and it also doesn't do it round there either. When i flick it onto orange channel it just cuts out mid strum.

b) Lack of gain on the red channel. It sounds dull, lacks sustain and generally sounds bad. I switched the 4 6l6s for 2 EL34s and changed some of the pre amp tubes and it sounded slightly better but i'm sure theres something more serious going on.

c) THIS IS THE BIG ONE...The tone controls don't seem to do much, they're not very responsive at all. The treble control is especially screwed. As I turn it UP the amp gets quieter :S

This is my first Mesa and I really have no idea what's making it behave this way if anyone has any ideas it would be GREATLY appreciated. Thanks.

 

[Guitarted]

Yikes! Sorry to hear that. Unfortunitly I can't help; I am not an amp tech. It's a shame that such an early Rectifier is so f'ed up.

 

[Boogiebabies]

Well, the old 2 channel has 20+ LDR's for the complex switching system.
If one or more go out, the amp may not be switching channels or adding the necessary cathode caps, tone stacks and other functions that make the amp sound as it is supposed to. Also, after time the tiny cheap pots will go bad or get so dusty that they do not work. You have to check them all with a multi meter to see if they sweep the proper resistance. Cleaning them first will help. A general peek at the circuit board may yield a cold solder joint or a burnt spot that may lead to the culprit. If you feel uncomfortable poking around, use a # 2 pencil and the eraser to wiggle the components. Look at the big blue filter caps and see if they are leaking or have a corrosive look on the sides.

 

[Botch]

Thanks for the replies. Well after much panicking I called a few people and found a tech that was recommended by a few music stores so I took it down today for him to give it a look at. I figured if it was in this state the previous owner probably hadn't had it looked at for a while so i thought I'd let a pro take look at it. Fingers crossed it fixes up OK...I'm determined to get it back to how it should be.

 

[tele_jas]

My Tremoverb head (1995 dual rectifier) had a similar problem, and it was a LDR... It took my repair guy about an hour with a soldering iron and a can of air to do the heat/cool method to find the LDR with the problem. Once he found it, it took him about a minute to swap out the $2 part and cost me $75, but it was worth it!

That's what it sounds like is going on with your amp too.

 

[Boogiebabies]

If it makes noise, you cannot be in that bad a shape.

 

[Botch]

Cool, that's good to hear. I'll post an update when i speak to him again. Could someone explain how the MID and TREBLE controls work on the amp, because right now the mid has to be set at 3:00 and the treble at 9:00 for it to sound anywhere near decent. The 'instant gratification' settings from the manual are pretty much unusable on this amp. what my main concern is the fact the treble control makes the amp louder as you turn it down.