Mesa Mark IV Issues

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Hello. I'm new here. I've been having some issues with my Mesa Mark IV for a little while now. I've called Mesa and searched constantly to figure this out, but it doesn't seem that I will find a solution to this.

A few weeks ago, my amp was making random noises every once in a while, sometimes it would get bad. Not sure if it was an unshielded cable causing that or what. I also noticed that one time it got really bad sounding and I turned it off, and happened to look in the back. The power tubes were glowing extremely bright. I think it was "red plating"?

Fast forward to my next show. We played our set and on our last song, towards the end. The amp loses volume, then completely dies on me. (Lights and everything). The next day. I changed the fuse, thinking it was the venues power that blew out my fuse.

I found a replacement, and proceeded to practice on the amp. About 30 minutes in. The amp shuts off again. I check the fuse, and it is blown again. I then read up that it is most likely caused by a power tube failing. I went and bought a new fuse and 4 new Mesa 6L6 tubes. The only problem I have now is.. I'm sort of afraid to use it because when I turn it on full power. A few of the tubes start getting bright.

http://i.imgur.com/pvMJEBX.jpg
http://i.imgur.com/Bq6MjnC.jpg
http://i.imgur.com/elso4r8.jpg
http://i.imgur.com/dLazWTJ.jpg
http://imgur.com/3yCBO7o

Do these look normal, or are they "red plating"? I think I might be a little paranoid.

On a side note. When I use my amp in Tweed power. It looks "normal" to me. No bright plates.

What do you guys think it could be?
 
Furthest valve is definitely red plating.

3yCBO7o.jpg


Other valves maybe, dunno for sure or whether it's reflection of the heater element on the glass without seeing it in person. Which you probably don't wanna pay the shipping on.
If you count em 1 being nearest, 4 being furthest in this pic. Then 3 is redplating too. Valve 1 could be reflection.

elso4r8.jpg


That the amp bias is fixed means you have no way of lowering the bias. The grid resistors could be failing. But as the valves are wired in pairs (outside pair and inside pair). It's no job for guesswork to suss why valves 3&4 are redplating. It could be caused by the output transformer going. I saw that recently on a JCM900. Had it myself on a used 800 where the transformer was fine until the volume got to 6.

If your amp has a variac/tweed power setting, you could try powering up in that setting. But the general rule is once a valve has redplated it's broke, it needs to be changed. So if you buy a new pair, you could just be throwing good money after bad. May as well take it into a repair place
 
Are you saying that the brand new tubes I bought for this amp are done for? They still sound fine in both settings, I just use Tweed Power now though. Is the output transformer a huge expense to fix? The manual for the amp said that if a fuse blows, that I'm suppose to get new tubes for it. Plus, that was the general consensus online and when I called Mesa. They just told me that the power tubes failing blew the fuse and it wasn't likely to have been caused by anything else. So, I went downtown and paid 100+ dollars for the tubes and now I'm being told afterward that I just ruined the tubes..?

If that's true.. This is really frustrating. Making me really consider just going back to the Axe-FX or maybe Kemper.. Hell, I'll take a pod bean at this point. Tube amps around me seem to be failing left and right and I think it's about time for me to hang em' up and move on.

I really appreciate your help. Thanks! :)
 
Yeah mate, ruined new valves.

A firmly fixed bias amp, like a Mesa. Shouldn't redplate ever. What that excessive heat has done, is change the structure of the anode (plate) of the valves that redplated. On a molecular level. The integrity of the valve is ruined, you can't guarantee it's continued performance. It needs to go.
It's different for a variable fixed bias amp, like Marshall/Peavey. In that it can be cured by adjusting the grid bias, restricting current from anode (plate) to cathode. You still have to change the valves. However what caused the valve to pass too much current (grid bias) needs to be addressed. For a Marshall/Peavey type circuit a Mr Joe Normal like you or I can learn to do that, without too steep a learning curve. However checking the condition of the bias resistor or the plate voltage, that has to be done while the amp is running. Then getting the circuit board out and replacing any blown components. Is no job for the layman.

There have been tomes written about this. This fella is no lover of Boogie. He is however very skilled and about the only person I'll let work on my Watkins gear. I'm linking this just to show that every company knocks out a duffer sometimes. It could be the valves, it could be the last set of valves going that caused a problem in the circuit that has now ruined the new valves.

http://www.amp-fix.com/biasing.htm

On red plating and why whoever told you that the valves would still be OK are absolutely wrong

https://en.wikipedia.org/wiki/Glowing_plate

Your only option is to take the amp to someone who repairs valve amplifiers. Diagnosing why this has happened over the internet is impossible. There's a chance, albeit slim. That if you switched the amp off very quickly, when you saw the valves redplating, that the valves haven't become damaged. However they need to go on a valve testing machine to determine that. Any amp repair person worth using will have one.
When you get your amp fixed, get your old valves back too if they get replaced. I've seen less than honest people pass old valves off as new.
 
FWIW a valve blowing isn't the same as a valve red plating.
A blown valve will spark internally and cause all kinds of noise. Then blow the B+ fuse.
A red plating valve is simply a valve trying to operate outside of the parameters it's capable of.
 
Thanks for the replies.

No one told me they weren't ruined. I was just saying that when I play on tweed. They don't red plate, and the amp sounds just fine.
However, I do understand that the tubes could be ticking time bombs now.

I'm still deciding whether I want to give this to an amp tech and then have to buy all 4 new tubes (spend 200+ if not more) and could
still give me issues in the future if even ONE thing isn't caught. It's like a car, sometimes things just nickel and dime. When I look back
on all my experiences with tube amps and with other people and their tube amps.. I just see failure constantly. I am pretty much going to
assume and guarantee that you have a different experience and will absolutely swear by tube amps as the ultimate in tone and reliability.
I could be wrong about that, but.. In my experience, tube amps don't seem to be worth the metal they are made of.

I'm not knocking Mesa specifically, it's all tube amps that I have experienced, which are various brands. That completely screw up and were
properly maintained even.

I think I'm just ready to go back to the AXE-FX or even use my computer live with amp sims. At least I can repair that myself without dying
and spending a fortune. Like I said.. I'd take a Line 6 Bean over dealing with another tube amp again.

I do really appreciate your help, thanks! ;)
 
I've owned a few tube amps from a few different makers and I've never had an issue. I got my Mesa used 10 years ago and it is now 15 years old and going fine.

I have little to no knowledge on how to fix amps so if I had the problem you described, I'd have just taken it to the tech first before investing in new tubes but nothing you can do about it now except take it in to get it looked at or cut your losses and sell it for an SS or modeling amp.

If you feel the upkeep is not worth the sound you get out of the amp then just get rid of it. It'll save you the aggravation you seem to have with tube amps down the road.
 
Yea, I wish I would have just taken it in. I told Mesa the details, and they just told me to replace it. Even if you think that is not likely, I remember it clear as day.
I just got done playing it in tweed power to see if it sounds weird. It sounds ridiculous in my opinion without the need for pedals.. I gotta get this thing repaired.

I was sorta venting about the upkeep. Just got frustrated because I want it to work, and love this amp.

I don't currently have a backup, and have a show on the 15th. Amp techs in my area have told me that the wait time is in the weeks, possibly months. :|
 
Missouri actually. When I call up amp techs, they usually say that they have a bunch of amps that got dumped on them. I understand why there is a long wait, it just makes it tougher to recover from an amp messing up.

Amp techs seem to be kinda rare. I've heard of some places letting their amp techs go and didn't refill the position because it wasn't profitable enough to keep them. That is pretty sad to hear, and makes me worry about the long term when it comes to tube amps, if no one is really around to fix them, and you can die trying to fix it yourself. :|
 
The upkeep on a valve amp, isn't hard. It's something everybody can learn to do for themselves.
Trust me, I'm an uneducated plasterer from England. I only went to school to sniff glue and muck about with my mates. The only test I ever passed was my driving test.
There's loads of free information out there on the world wide web. There are plenty of good experienced people willing to advise. If you can work a calculator, a screwdriver and a multimeter. You can bias most amps (except Mesa, that do still need it from time to time due to component value drift).

Your problem is that you received less than accurate (I suspect) advice. Now that may or may not be down to how you described your problem. It leaves you with one big must though.

You have to get the amp fixed.

Even if you decide to sell it. A bust amp is going to sell for between a quarter and a half of what a repaired amp will sell for. I just seen a guy on Facebook a shop tried to rip him off on a bust triple rec. He ended up getting a LP Standard and an LP Studio out of the deal. Bust amps are a non seller. Even selling them to people that fix amps you never get anywhere near what they're worth. I'm currently selling a JMP2203 I bought bust, it cost me £120 for a OT for it. I bought the amp for £240, selling it at £800. Which is about the going rate for em here.

If you decide to keep it, what's the point in having a bust amp kicking round the place?

That the amp works ok in Tweed mode is a get by, at best. What happens in Tweed mode is that all the voltages that the valves see, are reduced. So the valves are never put in a position where they are struggling to cope with what's going on. Now a change like that is going to be caused by one of two things, a component has failed or shorted. Or a circuit trace/ground has become open.
You should at least take the amp into a repair place and get them to have a look and tell you what's gone wrong and how much it will cost to fix. Before you make your mind up about whether to keep it or not.

Two important rules to remember

1, People need to physically see things to ascertain their condition
2, Don't believe the internet.

I dunno how old you are. But you know how mechanics used to look at the spark plugs of petrol cars to tell them what is going on with how the engine is running and how the carburetor is mixing the fuel and air. Well valves are the same thing but for amps. They are indicative of how the amp is running. Just like a sooty spark plug shows the car is running too rich, a scorched valve shows an amp is running too hot. Rather than the valve causes the amp to run too hot, just the same as the spark plug doesn't cause the engine to run too rich.
There's one reason why this "oh it's the valves need changing" near constant reply is so common these days. It's because people make money from selling valves. However modern valve production isn't bad at all. I've two toolboxes full of used valves that are in great condition, just waiting to be paired up. Because people believe this nonsense and insist on having their output valves changed every six months. A friend of mine has a 1985 JCM800 that still uses all the original valves. It's never had more than a tweak to the bias pot. He plays about 3 loud shows a month. My 800 has a five year old set of JJE34L's in, that have gigged weekly.
 
That was very informative. The analogy of spark plugs and valves/tubes puts into better perspective for me. I really do like the amp and do want to keep it. I just kind of get panicked when I own something that only a person with specialized training can repair and they are seeming to disappear from shops, which seems crazy to me that it wouldn't be profitable enough. Makes me wonder if they will eventually disappear completely. :(

Yea, it sounds like no matter what I do. I have to repair it. Since I really do love the way the amp sounds, I think it is worth it to keep it, and really hope that if I do everything right with the amp, it will hold together for a long time.

Thanks again for the advice. I am learning some important stuff. :)
 
No problem mate, really.
One thing I will tell you from experience, it's probably not as bad as you think it is.

Anyone with an electronics background will be capable of diagnosing and fixing the amp. Valves and transistors essentially work the same way, at the bare bones of it. Valve amps are meant to be repaired, these electronics people look at the rise in popularity of valve technology and are amazed by it. Even if they have nothing to do with amplifiers.

And the fella that used to work from a shop. Probably now works from a garden shed or his garage or something.
Years back, when I built my first amp, a very basic 18 watt Marshall clone. I ended up taking it to a guy to sort out. Basically, you always muck your first one up when you're uneducated in electronics. Now I'm lucky enough to live right between the Laney, Marshall and Carlsboro factories. They're all 100 miles in different directions of my house. So there are a good few old chaps round here with good knowledge of guitar amps. The fella I took it to has mainly been building transistor monoblock amps rated in thousands of watts. His own valve amp line. Doing repairs and winding his own transformers. Since the 1970's. He worked on PA systems for Michael Jackson when he last toured here.
He works from his garage.
Repair isn't the same as production. Look at Randal Smith. Guy invented the biggest game changer since the 100 watt stack, from inside a shed.

Try asking around the local players who they use. Or the shops.
 

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