Time for new tubes?

[bird_droppings]

When I turn on my Mark V, all three channels light up on the foot switch. But if I just play, I get my preferred channel 1 by default So I don't usually bother specifically selecting channel 1.

But. Every so often now, on startup, my amp sounds like a busy bug zapper until I choose a channel. If I choose a channel, the bug zapper noise goes away and stays away.

My amp is about a year a half old.

Questions:
1. Is this a tube problem?
2. Is the above enough to diagnose which it might be?
3. Should I just put all new tubes in? Or should I wait until the problem gets worse and I can diagnose a specific tube?

Thanks!

 

[search4tone]

The foot switch and the cable in particular can be a PITA. I turn on power I step on each channel to activate each relay switch then choose whatever channel I'm going to use and take it off Standby. If it's still making odd sounds it's because I've somehow got the cable out of alignment. Back to Standby, reseat the cable and everything is fine. I'm not an amp tech but it doesn't seem like it would be a tube function from what you are describing. I'm hoping Mesa creates a fix for this besides just trying to place the cable so it doesn't move.

 

[bird_droppings]

Interesting.

It never occurred to me that it might be the footswitch. But that makes sense. Twiddling the channels always makes it go away. And it only comes back occasionally when I turn the amp on again.

Well, I have a complete set of replacement tubes. I think I'll just hold onto them a little longer then.

Thanks!

 

[boogieman60]

When you turn on the Mark V, all the channel indicators light up. You should at once select a channel and the Quirks that you mentioned will be prevented. It also is a good time to check all the footswitch functions to make sure the cable is hooked up properly otherwise you may be doing it on your first tune..

 

[Adambomb]

Yea that footswitch can be a big pain. I got some noise from mine and even the EQ switch wasnt working half the time, so I had to send it off to Mesa. But that noise I dont think is tube related. Check the pin connectors on your footswitch and make sure they arent bend and making contact with the cable. Move the cable back and forth once its plugged in and check all switches on footswitch.

 

[bird_droppings]

Well I finally got to the bottom of this problem.

It got worse and worse. When I would turn on the amp it would start making a sound like "tika-tika-tika-tika..." and it would keep doing that until I would select a channel.

Eventually I couldn't even select a channel. If I took the footswitch off everything worked fine (although it is much less convenient to switch everything manually.

I called Mesa and they told me that it might be the footswitch cable and they recommended starting with that. I ordered one, but that didn't help at all.

I finally did what I should probably have done right from the start and took it to the repair guy. He told me there was a little circuit that converted footswitch signals to solenoid instructions (the little mechanical devices that actually switch channels) and it wasn't getting enough power. He had to replace two small components and now everything seems to be as good as new.

He also told me that as near as he could tell from looking at the footswitch circuit, there isn't a lot of surge protection for the circuit and he recommended only unplugging or plugging in the footswitch with the amp off.