Mk V Head acting up

[BigBadWolf]

(start reading this by mentally adding 5 lines of colourful swearing of your personal choise in here)

I bought my mk V head second hand and with an issue of some minor tubeish noise when reverb was used. Since that didn't actually disturb me, i let it be. Also i've noticed problems in effects loop jack (or that is what i've thought) which have gone away when pulled and pushed the plug (those who have children know the routine) continuously. It has been in moderate home studio use and in that, real volumes have rarely been used. Tonite i decided to swap it with my combo and took it in real work. At this phase it began its own show.

It loses power, somewhat half of what i think is pre-amp power occasionally. Problem is linked with channel changing. When the sound comes back, it is normal. Until i change to another channel when it goes away again. Beating the head doesn't help. However strong open Em played gives the power back. There are just few things what an open Em played thru Meesa Mark can't fix ;D

Of course it is about resonating. Silence seems to do bad to it, since after quitting a piece it lost some contact before the next one again. And almost every chanel change dropped the power out of sound. Not out of amp, but sound.

Seemed somewhat like dying tube in V1 position, but i never heard of that kinda tube in which lost power comes pack. Gotta admitt that i have had very little amount of tube failures in my amps and even less when i changed to Mesa's. Knowing that (and the fact that tubes do work more using magic than electricity) it is of course possible that we have just bad case of V1 here.

However it is a head and owners of those know that you just do not change V1 in between 2 songs to that. And i'm not getting the amp back to my hands before tomorrow either. So i spend this time to asking stupid questions. :lol:

I performed the usual acts between (and in middle) of our set: Pedal cable off and switched channels using the knob in behind, did things with loop jacks which published in youtube would've given me strange but interesting reputation, checked all other chords and connections. Nothing helped. Few observations thou.

- From the beginning amp seemed to need more master volume than my combo.
- It sounds and feels like the volume drops in 1st gain stage and happens in all 3. Drops drive off from hi gain.
- While volume drop, there is lots of noise which disappears when power comes back
- I had to change in fly from Fat to Tweed to get my cleans right
- Switching channels triggers it practically every time
- A hunch says it's the butler ... err.. loop, but switcing loop off and taking plugs outta it do not fix it. And part of facts say it isn't

Last observation was that a head owner needs to hire at least one pygmee or educated minor to take care of mk V head on road. If like me, sized (and sadly also looks generally) like people who are getting roles in gangster/biker movies, fitting hand in head chassis is practically impossible. That may tell us that V1 hiding behind one huge transformer has never been changed in this amps lifetime.

Mesa: Y u no use another inch of wood to each side (one side could help, but would look somewhat unprofessional) of the cabinet?!?

If someone has had similar things (and heart enough to forgive me my not so serious style to write), it would be nice to hear of those before i start doing anything bigger with the amp.

Never seen how dying rectifier tube acts. However ch 3 is in 90 Watt. Why could it effect there?

Hints where to start? V1 is obvious. Just in case...

 

[Tat2pooch]

I would change out all the tubes, or go through a process of elimination by tapping the tubes with a pencil eraser, if you hear crackling noise then def change that tube. Most problems are tube related...if then you still have issues you can prob call mesa and they could help you out.

 

[Tat2pooch]

You might have to take the chassis out to replace some of those hard to reach spots

 

[BigBadWolf]

You might have to take the chassis out to replace some of those hard to reach spots

Actually removing the reverb tank did the trick. Took some serious finger power to open one of the screws with fingers since no appropriate tool was found, but otherwise quite easy. Gotta get me some kinda angled philips screwdriver...

However changing tubes didn't help. The sound of course came somewhat stronger. For that we can be sure that the tubes were near their end. But the original buzz is still there.

Now it hapens only in ch1 and with reverb on. I'm just waiting this whole show starting all over again.

 

[BigBadWolf]

I decided to crack it open and find out what's bugging it.

At this point i suggest that it is perfect time to add the "Do not, i repeat, do not do that unless you're sure you know what you're doing".

It didn't actually take long 'til i noticed that V1 tube base is loose or broken. Tapping it with good ole drumstick (avoiding metal tools when touching things in full operating amp helps you live longer) makes wrong kinda noise. Since i have additional "evidence", i believe i know what has happened.

That long tube cover wasn't straight when i first paid attention to it. Since the head cabinet has not enough room to take it out, i left it alone and forgot whole thing. Now, when i changed tubes, i noticed that said cover was bent. I believe that it has seen some force. Looks like some of previous owners decided to change V1 without removing the reverb tank, used force to get cover out and in that managed to twist tube in it hard enough to cause damage in tube base.

Eased the pain a bit with this. Althou still broken, at least it looks like it's not the amp broken all by itself but some human with 5 thumbs per one hand caused this.

So if you're buying used V head, check the V1 tube cover. If that one is not standing straight, there may be damage. Never buy and amp where somekinda noise comes and goes in trust that you can get rid of it by changing some tube.

Funny, but it has wires that are microphonic. Not sure if this is how things should be. However this just strengthens my opinion that tube amps use more magic than electricity to provide sound ;D

Sadly i found V's inestines difficult enough to notice that my skills have ran out. Taking that to a pro shop to be fixed.

 

[OldTelecasterMan]

I'm not understanding the tube replacement issue. I replaced the tubes in my Mark V head after about two years just because I felt it's about time. And it was about time as the amp sounded brighter, tighter and not as mushy. When I am gigging a lot I change tubes in amps about every two years. If I am having a really good year, 2 or 3 jobs a weekend, I change them once a year. I have not had much trouble changing tubes even in the Mark V. I put the head face down on the floor (carpet) and change them. I have big hands, 6' 4" 225lbs I also play piano and I can reach from the "C" over an octave to the "E". So getting tubes changed from what is said here should be difficult for me but it's not. I do, always, pay attention to the positioning of the pins on the tube as I bring them out and I put the new tube in as I go through. Tube out, tube in except for the power tubes cause you can see how the receptacle is positioned. I also have an inspection mirror if one is giving me trouble so I can look at the pin holes. I work slow and never force.

However this just strengthens my opinion that tube amps use more magic than electricity to provide sound ;D

About the "Magic" I don't find this true for me but I do know that I hate it when I cannot or especially if I thought I couldn't use my Mark V at a job. Like when it is a small venue, or I hear the stage is real small and space is an issue I take my Boogie F-30. The F-30 is a great little all around amp but I am soooo spoiled from my Mark V.

 

[BigBadWolf]

I'm not understanding the tube replacement issue...

Dunno if there is any more issues with V-head than V1. As my amp clearly shows, the big tube cover behind large transformer has been troublesome enough to cause damage. I took reverb tank off to avoid any mistakes. Possible or not, better be on safe side.

About the "Magic" ...

Since it was actually me who wrote about magic, i guess i'll have to return to that once more. This one is easy.

There is no such thing as magic in real life nor there is anything in this world which we could call supernatural. However we have this thing called "Sense of humor". Sadly amount of it differs in humankind.