Mark IV Footswitch R1 not working...please help!

[UsrName]

Okay, everything has been working fine since I've had the Mark IV, until this weekend. I took it to jam with a full band for the first time and it worked fine when I got there, but after a couple hours, I tried to switch to R1 and nothing. I tried again and it would switch to Lead+EQ, again and it would switch correctly to R1.

So when I hit R1, sometimes it will go to R2, or Lead+EQ, or R1. I sprayed contact cleaner into the switch and switched it on and off a dozen times to work it in, but the problem still remains. I also adjusted the manual channel knob on the rear panel and back to the footswtich setting and made sure the plug was seated tightly into the amp.

One note: the whole band, with the exception of me, was smoking like a chimney the whole time. Could the smoke have caused this problem?

I would be grateful for any help, especially the kind that will avoid buying a new footswitch! Thanks fellow Boogiers!

 

[Pinweaver]

The first one who smokes in the company of me, my guitars and my Mark IV will have a more serious problem than lung cancer. 8)

 

[Restless Rocks]

You can narrow it down to the footswitch or the matrix logic control inside the amp by removing the footswitch from the amp to see if the rotary channel selector switch is functioning properly. Don't spray a bunch of contact cleaner in the footswitch; this just makes it messy inside and smoke is probably not a factor. Either way you'll need a good tech for this one. replacing chips is a whole other league from pulling tubes.

 

[UsrName]

You can narrow it down to the footswitch or the matrix logic control inside the amp by removing the footswitch from the amp to see if the rotary channel selector switch is functioning properly. Don't spray a bunch of contact cleaner in the footswitch; this just makes it messy inside and smoke is probably not a factor. Either way you'll need a good tech for this one. replacing chips is a whole other league from pulling tubes.

Well, I disconnected the footswitch and the channel selector switch functions as it should, so I guess the problem lies with the footswitch itself.

Any ideas anyone?

 

[Restless Rocks]

Yes it would seem that way. Check the cable to the footswitch to see if it has been damaged or cut. Plug it back in snuggly to make sure it is not a dirty jack on the amp or that the cable may have been pulled loose in the plug. You'll probably want to send it to Mesa for repair.

 

[rockhound76s]

I had the exact same problem earlier this year, and my amp was out of warranty.

I tried to troubleshoot over the phone with Mesa, but they said it was too difficult to pin down the problem without seeing the amp, so I drove it to the factory.

I was worried that I would have to get a new footswitch (which costs $219, BTW :shock: ).

They were totally cool and replaced it for free. They said it was a loose cable relay, and fixed it in a matter of minutes. I don't know much about electronics, so you might try calling them and have them guide you through what to do if you have experience with that sorta thing.

 

[UsrName]

They said it was a loose cable relay, and fixed it in a matter of minutes. I don't know much about electronics, so you might try calling them and have them guide you through what to do if you have experience with that sorta thing.

So was the problem in the footswitch or the amp itself? Did they say what could have caused it to become loose?

 

[Shep]

try cleaning these switch contacts..have a look in your footswitch for any lose wires or parts.. it's something thats come lose...

 

[rockhound76s]

So was the problem in the footswitch or the amp itself? Did they say what could have caused it to become loose?

The problem was in the footswitch. They said that occasionally they see this problem with Mk IV footswitch cable because they are not detachable from the footswitch. They said to avoid wrapping the cord around the footswitch when transporting, and to be careful to not step on the cable/footswitch joint.

 

[UsrName]

Well, I opened up the footswitch to see if anything was loose. everything seemed to be fine. There is a circuit board which houses R1, R2, Lead and Lead+EQ switches. I tested the switches with my multi-meter to make sure they made and broke contact. They worked fine.

I then tested continuity from each of the pins on the connector to their respective end on the footswitch, which also worked fine. So, no problem with the cable and no problem with the switch itself.

There are three socketed ICs on the board and I'm thinking one of them is the culprit, since all of the other components checked out fine. I will call Mesa Boogie today to see if they can help. Hopefully I can get these chips and swap them in to test it, or I'll probably have to send it in for repair.

Thanks for everyone that replied and I'll be sure to post the results when I find what the problem was.

 

[UsrName]

Well, not much help from Mesa. They told me to contact my nearest service center, for which they gave me the number. They would not even talk about it over the phone and said it would probably be cheaper to get a new one as opposed to paying them for parts AND Labor.

Good news though, I found a one in the classifieds and should have it fairly soon. I'm going to use that one to troubleshoot this one and I'll be sure to post back with the results 'cause you never know who might need help with the same problem.