Mark V as it relates to Mesa's "troubleshooting" video

[Jiveman]

I watched that troubleshooting video that Mesa put out (http://mesaboogie.com/news/2010/11/mesa-amplifier-tube-troubleshooting) and I guess I'm not quite 100% clear on how some of those things apply specifically to Mark V. This is probably mainly because I'm new to tube amps in general, so anything tube-related is a new world to me (but I'm learning ;-)). So I figured I'd throw all the questions I have out there and hope that you guys can clarify.

For example, in the video, they test the tubes one by one, starting with ONLY the rectifier tube(s), then adding power tubes (i.e., testing ONLY the rectifier tubes AND a single power tube, and so on). First question, is that ok to do on Mark V (only the rectifier tube + one power tube)? Does it matter if the switches in the front are set to 10W vs. 45 vs. 90W modes? I imagine to test the rectifier tube alone, you'd have to flip the switches to 10W mode, correct? How about when you add the power tubes?

Then... Is it ok to perform these tests WITHOUT the speaker/load plugged in? The manual says NEVER to do that, yet in the video, they "test" the power tubes by turning the power AND standby switches without the speaker cab. Is that because they're only briefly toggling the standby switch?

Preamp tubes... How do you test those on Mark V? They seem to be pretty hard to reach with all the power tubes plugged in. The power tubes DO have to be all in while tap-testing the preamp tubes, correct?

And just for general reference/knowledge... Can a rectifier or power tube be "going bad" but still be operational? In other words, if the amp works (there is sound), would going through these motions (shown in the video) still be beneficial as a preventive sort of thing? For example, I bought my MKV used, and I'm still only scratching the surface of knowing everything I should about it, so once place to start would be to make sure all tubes are in good working order (without just blindly swapping them with new ones).

Thanks!

Noob out.

 

[lerxst88]

I would think so; 10 watts for testing the rectifier.

While you MIGHT be able to get away without a speaker, take a look at the receipt for the amp and re-evaluate. Is it worth it?

Try removing the chassis to get to the preamp tubes. On my Mark IV and on my old Nomad there were 4 screws on top. Take out the chassis and hook everything up (except for reverb cuz thats a pain in the ***) and you should have much easier access to the preamp tubes. Test them with the power tubes in.

If the rectifier tube wasnt working you wouldnt get any power. I suppose you could check it but wouldnt you rather be playing? Tube amps are pretty sweet because if theyre working, youre good to go. If something is amiss, just pop in a different tube and youre good to go again!

One thing they didnt mention in the video is to replace power tubes as a set. I wouldnt feel right just changing ONE power tube whenever one went out. Replace in pairs or quads and try to get them matched whenever possible!

Either way if it sounds good, your tubes should be good!

 

[rocknroll9225]

I would think so; 10 watts for testing the rectifier.

While you MIGHT be able to get away without a speaker, take a look at the receipt for the amp and re-evaluate. Is it worth it?

Try removing the chassis to get to the preamp tubes. On my Mark IV and on my old Nomad there were 4 screws on top. Take out the chassis and hook everything up (except for reverb cuz thats a pain in the ***) and you should have much easier access to the preamp tubes. Test them with the power tubes in.

If the rectifier tube wasnt working you wouldnt get any power. I suppose you could check it but wouldnt you rather be playing? Tube amps are pretty sweet because if theyre working, youre good to go. If something is amiss, just pop in a different tube and youre good to go again!

One thing they didnt mention in the video is to replace power tubes as a set. I wouldnt feel right just changing ONE power tube whenever one went out. Replace in pairs or quads and try to get them matched whenever possible!

Either way if it sounds good, your tubes should be good!

+1 to everything he said. i'd think you could also check the rectifier in 45 W on channels 1 or 2, with the toggle in the back set to tube.

and NEVER EVER EVER turn your amp on if its not plugged into a load. doing so will fry your amp. you can turn it on and leave it in standby without a speaker connected, but i wouldnt recommend it. thats just asking for that switch to accidentally get flipped.

 

[Jiveman]

Thanks for the words of advice. Yeah, I always thought that I wouldn't want to turn the amp on without the speaker load, but it seemed they were doing that in the video, so I wondered.