Mesa Boogie 50w Rectoverb needs an exorcism!!!

[stokes]

bob,I dont mean to sound like I totally disagree with "books" or that the data you quote is wrong.I do dissagree with your first observation that it is most likely caused by a poor solder joint,and I base this on "odds".Like what are the odds that the Mesa factory did a poor job of soldering and then somebody else did a poor job twice.And the statement that if the component heats enough to melt the solder that it is probably shot,I know if the heat is left there too long of course the component will fry,we dont need data to tell us that,we all learned that the hard way at one time or another,but in this case it doesent seem to be the case,as the res.is popping out while playing,so the heat could be just enough to melt and then the component is knocked loose,just the reverse of installing it.In this case it is likely going to be tough to diagnose the problem with the amp idling as it seems to be occuring while he is playing,I would bet if you check the current on that screen at idle it will seem normal,if that werent the case the tube would probably blow when a signal is applied for a while.While the scenario and fix Rob described with the evil twin would be fine for that part of a circuit,I think that type of fix would be detrimental in a screen circuit,kind of like putting a 3amp fuse in place of a 1 amp to keep it from blowing.Its obvious that we have different approaches to these problems,and it may sound like we are being argumentative,but different opinions are what keeps these boards going.If my comment about "getting your head out of the book" seemed offensive,it wasnt my intention,it was said as half a joke,if you took offense,I appologize.I just feel there are a lot of times that books and formulas and math are more time consuming than they are worth,and it would seem,that is where you and I disagree the most.Hey,we could be completely wrong on the dignosis,we are after all just speculating based on what we are being told.Now,if we havent completely bored the poor guy who started this post to death,maybe he will tell us how he made out.

[Enzo]

And it depends upon the part. If a 5W wirewound resistor unsolders itself, it will have been stressed a lot less than a film or composition part would have been.

[Steve Conner]

You do have the right impedance of speaker hooked up to the right tap?

[Peter Clothier]

Non of this would be an issue if Amp manufacturers used quality components and methods. High watt ceramics should have plate type legs with 2 or 3 tabs at the end to form a reasonable mechancal connection with the board. But of coarse this is all extra expense to our accountant led profiteering manufacturers.

We have all heard the arguments fore and against PCB valve amps. It is very very rare that a fault on a PCB amp is down to the PCB itself. It is almost always down to the crap they stuff in it everytime.

" If it were good enough for my Grandad, It's good enough for me." A famous Yorkshire phrase. What a load of bolloxs.

[Mars Amp Repair]

My 2 cents...I couldn't agree more...I've been working on stuff with PCB's in it for years...pcb's have no inherent issues as far as I'm concerned other than poor waving, cheap phenalic, or traces that evaporate when you touch your temp controlled soldering iron to them, which all really just translates to a cheaply made board.

The toughest part in music amps that I run into is where the design makes it very difficult to get to the reverse side of the board without disconnecting just about everything in sight..then you can't run the unit in that state.

Then ya just gotta look at it & say...what the hell where they thinking....mostly cost savings me thinks...g

[Steve Conner]

Well, how much do you guys want to pay for your amps? If poor quality gets you down, you just need to boycott current production Mesa, Marshall and Fender, and insist on boutique, or painstakingly restored vintage amps, for which you'll pay twice or three times as much. Or build it yourself, which costs even more by the time you factor in your labour costs.

I work as a designer with a small electronics company, and we try our utmost to squeeze as much "customer impression of performance" as possible out of the fewest, cheapest components, with PCB fab and assembly subcontracted to slightly-trained monkeys in China, and then sell the resulting mess at as large a markup as humanly possible. If we tried making guitar amps, guys like you would have us for breakfast. I actually respect the above mentioned makers a lot for being able to mass produce tube amplifiers in the 21st century at all, and turn a profit.

Some people think that profit is somehow bad or greedy, but a company needs to make money to pay its employees, and then a little extra to reassure investors that it's not going to go bust any time soon.

[bob p]

I'd have to agree with you Steve -- making tube amps in the 21st Century just isn't do-able if you want to use 40+ year old production methods. The production cost of the amps would be so high that you couldn't produce the garden variety amp that way. Only the very expensive boutique items, and restored vintage items can be made that way.

With that said, I think that the Mesa production quality is pretty good. At least it is in my 1990s Mark IV head. Sure, there's a lot of stuff crammed into a small space, and it you ever wanted to mod the amp you wouldn't enjoy the job -- but on the flip side, Mesa did a really good job of shoehorning a lot of stuff into a small space, and the amp wasn't very expensive to purchase considering its features, top quality compoents, and assembly methods.

Mark IV Porn

There's no way on earth that I'd consider trying to build the Mesa out of parts -- its just too complex a circuit, and my production costs (NOT including labor) would end up being higher than the cost of buying the amp -- because Mesa buys in huge volumes and I don't.

Regarding profits, there's another thread about Gas Prices where someone said that anything over a 10% profit margin is unreasonable. I'd have to disagree. If manufacturers couldn't make LOTs more than that on manufacturing, then they would not be in manufacturing. We wouldn't have stuff to buy and we'd all be trying to build evertying in our basements or on our kitchen tables.