MKIII Problem

[ursinus]

About a month ago, my MKIII started loosing its volume when it would warm up. I changed the preamp tubes and the problem went away. On Friday, the family was gone so I shook the walls of my garage for a few hours through a Theile and a LSC 2x12 with Cannabis Rex's. I love this amp! Anyway, after about 2 1/2 hours, the volume would go down to a whisper and then come back up again. I haven't had time to open her up yet and probably won't for a few days as I have three customer's amps I'm working on at the moment. Anyone have any ideas what to look for? My first thought is that it is PI circuit because the problem occurs in all the channels. Any thoughts would be appreciated.

Thanks.....

 

[Schmoog]

any scratchy pots? disconnect the reverb and see what happens, also try patching a short cable from the effects send to the return. open the cabinet and look at the filter caps, see if they are bulging or leaking

 

[Restless Rocks]

Try Schmoog's advice. It's a very common problem on older mark amps for the FX loop jacks to become intermittent. Try some Craig's deoxit and while you have the chassis pulled clean the pots as well.

 

[ursinus]

FYI, Its a non-Simul Greenie. I'll have some time to look at it on thurs. I'll let you know. Thanks for the tips...

 

[ursinus]

does this problem happen at other locations (wondering if it's AC related @ your house).

man, and you're telling me i live in the middle of nowhere. if I blast my amp in the garage, the cops will be there in no time. do you have your garage sound proofed or what?

It happens anywhere in the house unfortunately..... My other amps don't do this.

My neighbor across the street is a cop who likes gear like I do and sometimes jams with me, so no problems with the fuzz. 8)

No soundproofing yet, BTW

 

[ursinus]

Wanted to give an update:

It was dirty connections on the send/return jacks for the loop. Problem solved. Man, I love my MKIII greenie as much as my Fuchs TDS100. :mrgreen:

 

[phyrexia]

Man, I love my MKIII greenie as much as my Fuchs TDS100. :mrgreen:

That's saying a lot as far as I can tell. People seem to like Fuchs.