ED Problem

[screamingdaisy]

Lost channel 3 (Vintage Hi).

When I switch to channel 1 or 2 the amp stays in channel 2.

When I switch to channel 3 the amp changes to channel 1.

I've tried disconnecting the footswitch and using the switch on the faceplate with no change.

The amp sounds normal... just can't use channel 3.

 

[YellowJacket]

Oh ****, no way!!! Perhaps call Mesa?

 

[ifailedshapes]

Relay gone haywire?

 

[screamingdaisy]

Problem seems to have gone away.

Hopefully it doesn't come back.

 

[J.J]

Yes, hope it stays gone, but whenever I have had a self repairing problem I have no trust until I know what happened. The fault will probably come back.

The ED switching is resonably complicated and has plenty of places something could go wrong. One area I would suspect is the foot switch sockets. They are required to be part of the circuit cable in or out and there are two. Either one with a dirty or slightly out of spec contact can cause the drama.

 

[screamingdaisy]

An issue with a contact makes sense. The combo sits on top of a 3/4 stack. What I suspect happened is the vibration of the stack cause the issue, and further vibration resolved the issue.

That said, I'm kind of stuck for the time being as it's really difficult to fault find a perfectly functioning amplifier.

 

[elvis]

I generally plug/unplug my cables a bunch of times in a row to break off some of the oxide that forms on the jack contact points.

I have also seen similar switching issues with faulty footswitch cables and with plugs that don't quite fit the jack right. An intermittent connection in the cable could easily be the cause.

 

[screamingdaisy]

It did it when the cable was unplugged and I tried using the channel selector switch on the face plate.

 

[elvis]

Wow. Didn't expect that. Could still be oxide on the switch contacts. I would toggle the switch back and forth many times. Tuner cleaner may also help.

Other than that, likely a bad contact inside the amp

 

[screamingdaisy]

I'm hoping it was just a bad contact and that it's cleared itself up or something.

That said, not much I can do about it now as I won't be able to track down the fault until it does it again...

 

[wekiitoedzo]

I had the same problem. The footswich's jack cable is a stereo cable and it had a contact issue. One filament got slipped out of the sealing. It can be due to carrying, dissasamble, etc. I simply seald it back, but also carry an extra jack in case.

 

[screamingdaisy]

Good idea.

 

[Nooner69]

Did you ever figure out what it was?

 

[screamingdaisy]

Nope. Hasn't happened again since.