Anyone with older Mark IV's send em to Mesa

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anomaly

anomaly

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Just got my very early Mark IVb back from getting fixed up and re-capped by Mike B and they said those 10,000uf 16volt sprague caps had leaked all over the board and caused a ton of damage, so it's not just the Mark IVa's it's also the early IVb's that have this common problem cause they share a lot of the same components as IVa's. They took 7 and a half hours of work getting the amp done and the price was enormous, but I justified it giving the current cost of Mark IV's and the fact that this amp has killed my amp GAS for the last 5 years. It sounds amazing, and even better now that it's re-capped and had a few upgrades.

Get it done before you end up with a rediculous repair bill.
 
That's a big repair bill. I'm struggling right now having a Triaxis repaired. Last chance is a retired guy that worked for the french Mesa importer in the 90s. If that doesn't work out, it will go to California with Fedex.
 
What year is your amp? Curious as to which batches of these go bad
 
Jack Luminous said:
That's a big repair bill. I'm struggling right now having a Triaxis repaired. Last chance is a retired guy that worked for the french Mesa importer in the 90s. If that doesn't work out, it will go to California with Fedex.
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Mesa does it right if you send it . I never hesitate. It comes back like new
 
Sending it to Mesa costs more, but their service charges are a lot less than local tech.... plus Mesa built and designed the amp, so sending it to them assures the amp will be perfect when you get it back since the know what to look for.
 
psychodave said:
Sending it to Mesa costs more, but their service charges are a lot less than local tech.... plus Mesa built and designed the amp, so sending it to them assures the amp will be perfect when you get it back since the know what to look for.
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I'm close to doing it. I have a Triaxis with a noisy lead 2 and a 2:90 with flickering mode switches. Both repairs are complicated apparently. Shoving both in a 3U rack case and sending everything at once to California seems easier now and more reasonable than it did 6 monthes ago.
 
i bought my mark IVa combo from mesa hollywood on ebay like 5 years ago. it already had the brown axials replaced, and the OP amp chip fix done (thank god), but they didn't do all the electrolytic filter caps. those can be done without removing the board, so i'll do those eventually. everything else sounds and works right, so i don't really want to send it to them with the way shipping prices are, and things are backed up.
Even when mike b retires, they'll still be perfectly capable of servicing all those old marks. he isn't always the one doing the actual work. he might test and diagnose, and then another tech does the actual leg work. at least thats how it used to be, maybe with covid its just him or something now, idk. He does have some of his own mods where you pay him directly (i.e IIB post fx loop mod and i think the C++), but i gotta believe they'll still be doable by someone after him. The guitarologist on youtube pretty much reverse engineered the IIB fx level thing on one of his videos.

to fix those damn brown caps they have to totally remove that big board, and it takes forever. here is a non-mesa tech, doing it, and probably hating his life for those few hours:
 
Holy crap that was amazing. Poor IV. It's like looking under the hood of a high end asian sports car. Everything is so jam packed with goodies.
 
dawnofdreamx97 said:
You don't have to remove the board guys , just did my 91 mark iv a... I made post about this already. If you need info on how let me know....

Wasn't that bad of a job. But the caps had not leaked yet on mine....
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Your idea of breaking those caps and soldering from the top and then gluing worked well for me. Got mine finally recapped last week.
 
TheGreatGreen said:
Mesa charging a grand to repair damage caused by a factory defect caused by a time bomb directly of their making is pretty shitty of them to do.
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I mean there really is no way to know the life of an electrolytic capacitor... that's not their fault honestly. Some of these Amps approaching 30 years old now .... just saying
 
blackba said:
Your idea of breaking those caps and soldering from the top and then gluing worked well for me. Got mine finally recapped last week.
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was it as straight forward as it seems or did you run in to anything unexpected? it seems like just shot gunning a dozen or so components. any particular resistors i should check out or replace that might take a beating? i'm going to get around to doing mine eventually.
 
dawnofdreamx97 said:
I mean there really is no way to know the life of an electrolytic capacitor... that's not their fault honestly. Some of these Amps approaching 30 years old now .... just saying
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mesa didn't know how shitty illinois caps were at the time. fender didn't either, because they're all over the blackface reissues, and hot rod series as well.
 
JimAnsell said:
was it as straight forward as it seems or did you run in to anything unexpected? it seems like just shot gunning a dozen or so components. any particular resistors i should check out or replace that might take a beating? i'm going to get around to doing mine eventually.
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All of the larger caps for the preamp and power section are easy. My suggestion is snip them out and use a needle nose and soldering iron to pull out the leads from the board , then clean up with a desoldering gun or wick.

The radials you literally just rock them side to side and back and forth while pulling up and eventually they will break off leaving you with just the barbs / leads which you can desolder and remove with a soldering gun / wick.

Tip , make sure you have time and patience when doing this. Slow and steady wins the race. Also reflowing some fresh solder in to the old pads while cleaning helps.

I stacked the radials caps on top of the preamp filter caps and secured with zip ties and silicone, using fly leads to attach them to the circuit card.
 
JimAnsell said:
was it as straight forward as it seems or did you run in to anything unexpected? it seems like just shot gunning a dozen or so components. any particular resistors i should check out or replace that might take a beating? i'm going to get around to doing mine eventually.
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there are two 3 Pin ICs T0220 package, Mesa typically adds a small plate as a heat sink to one of these. I didn't do this.

the main risk is lifting a pad or trace, which I did have one bad lift on the brown cap, but was able to get it soldered. I figured the worse case is I would have to pull the board.

Also some of the replacement caps were slightly larger than the original ones, so that made it a big more challenging, but overall I would say a medium skill level job. Solder wick as was mentioned was really helpful.
 
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