Mesa Boogie Mark IV brown leaky caps clarification

dr teeth

Active member
I bought a second Mark IV-A. It was the hardwood cab I thought I always wanted. That is until I picked it up fully loaded with the EVM 12L I love. Now I'm not sure. It's so beautiful and such a great amp but if I keep it I'll have to get a harbor freight small dolly to move it around until getting another combo case with casters.

After buying the amp someone told me about the brown leaky radial caps on the pre amp board so I searched and found people talking about horrid clean up jobs that the factory charges by the handful as it must be a nasty job. I pulled my newest chassis, sub-1000 serial # to have a look. I saw the 3 large brown radials sticking up but mine were 8200uF, not the 10KuF ones I read that everyone was having a problem with.

As a public service clarification for anyone else wondering the same thing I reached out to the factory.
Per Mike B:
"The 8200mf caps are NOT the leaky troubled caps. I have seen a few break loose from the board, but can't recall one that has leaked. The nasty ones were the SPRAGUE 10,000 16 volt."

We need to keep MB working so he'll get back to mods again.
So here you go in case you have the 8200uF and were concerned.

The filters and other E-caps like these are 30 years old now and it sure seems the "new" MB serviced Mark's have better resale value for now despite being contrary to typical vintage collectibles that favor all original. I usually only want replaced electrolytic's when one goes bad or there is sonic evidence (that would likely show on a oscilloscope) that they need changing. If I was gigging it and didn't have a back up I would change them but I do plan very soon to go through my Marks with an ESR meter to make sure the electrolytic banks are healthy. Even 50 yo caps can still be within spec while not expected to be and new caps can always be bad batches that you don't find out about till much later.
 

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Thanks for posting this.:thumbsup:
Feel like I dodged a bullet on this one. Did not want to have to ship it across country to Cali.
Put off looking at it for a long time due to that.
Took mine apart and here's what I found:
 

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yw, good to see!

what range is your serial? maybe we can hone down an approximate transition if people can chime in on the serials of 10k ones in version A

I still need to pull my other IV-A chassis which I'll do and report back but idr the serial on that one offhand
 
I bought a second Mark IV-A. It was the hardwood cab I thought I always wanted. That is until I picked it up fully loaded with the EVM 12L I love. Now I'm not sure. It's so beautiful and such a great amp but if I keep it I'll have to get a harbor freight small dolly to move it around until getting another combo case with casters.

After buying the amp someone told me about the brown leaky radial caps on the pre amp board so I searched and found people talking about horrid clean up jobs that the factory charges by the handful as it must be a nasty job. I pulled my newest chassis, sub-1000 serial # to have a look. I saw the 3 large brown radials sticking up but mine were 8200uF, not the 10KuF ones I read that everyone was having a problem with.

As a public service clarification for anyone else wondering the same thing I reached out to the factory.
Per Mike B:
"The 8200mf caps are NOT the leaky troubled caps. I have seen a few break loose from the board, but can't recall one that has leaked. The nasty ones were the SPRAGUE 10,000 16 volt."

We need to keep MB working so he'll get back to mods again.
So here you go in case you have the 8200uF and were concerned.

The filters and other E-caps like these are 30 years old now and it sure seems the "new" MB serviced Mark's have better resale value for now despite being contrary to typical vintage collectibles that favor all original. I usually only want replaced electrolytic's when one goes bad or there is sonic evidence (that would likely show on a oscilloscope) that they need changing. If I was gigging it and didn't have a back up I would change them but I do plan very soon to go through my Marks with an ESR meter to make sure the electrolytic banks are healthy. Even 50 yo caps can still be within spec while not expected to be and new caps can always be bad batches that you don't find out about till much later.
Boogie will no longer do this repair, clean job. Does anyone know who can clean the PC board on Mark IV amps?
 
Boogie will no longer do this repair, clean job. Does anyone know who can clean the PC board on Mark IV amps?
they said that? damn! i mean any good tech can do it, but they probably won't want to. so time consuming. there are a few guys on you tube who did it, you could email them and ask.
 
they said that? damn! i mean any good tech can do it, but they probably won't want to. so time consuming. there are a few guys on you tube who did it, you could email them and ask.
I don’t even know where to begin.
 
Boogie will no longer do this repair, clean job. Does anyone know who can clean the PC board on Mark IV amps?
Seems odd they wouldn’t work on it, i heard back from them today mikes backed up 2 months so they may be on pause accepting new repairs. Where are you at? My mark 3 I recently got was recapped and gone over by Hatt in lansing Michigan and they did an exceptional job.
 
Did they say specifically the brown leaky cap issue is a no go or something more general? Either way that sucks and it seems like the job from hell if they've leaked. And it sounded like there were levels of horrid so is yours bad? I'm guessing it isn't preventative if they're turning down a basic cap job.

Anyone with the 10k's should get them done if they haven't already shit the bed. It's a straight-forward relatively simple job when it's preventative.

Otherwise, what Jim said.
 
Seems odd they wouldn’t work on it, i heard back from them today mikes backed up 2 months so they may be on pause accepting new repairs. Where are you at? My mark 3 I recently got was recapped and gone over by Hatt in lansing Michigan and they did an exceptional job.
I’m in Michigan. The time it takes to clean the board is the issue.
Someone local is going to clean it. And he’s not charging me very much.
 
Seems odd they wouldn’t work on it, i heard back from them today mikes backed up 2 months so they may be on pause accepting new repairs. Where are you at? My mark 3 I recently got was recapped and gone over by Hatt in lansing Michigan and they did an exceptional job.
Here’s part of the email.

Some later Mark IV’s suffer from LEAKING CAPACITORS, which can badly contaminate the PC board, and which requires a massive cleanup of the board. If our tech finds this is the case on your amp - hopefully not - he can no longer devote the many hours required to fix these.
 
I’m in Michigan. The time it takes to clean the board is the issue.
Someone local is going to clean it. And he’s not charging me very much.
Have you verified the capacitors did leak? Could you post a pic of the mess?
I had an E-cap explode inside a Fender Deluxe reverb due to a faulty tube and I ended up using half a box of Q-tips to clean up the majority of the mess and then some Isopropyl alchohol for the remaining residue.
Took maybe 30 minutes
 
This may be the catalyst for the new policy- on ebay there is a IV right now down in Okieland listed as dead and the following:

"Had it to one repair man for 6 months with no repair (I should have listened to him). Sent it 3 times to another repairman who assured me he could fix it----still dead. Finally sent it to Mesa and got the sad news that it was too far gone for them to get it going. Their assessment was that the caps had leaked on the board and damaged it to the point that it was not repairable."

Sounds like they put a blanket over the leaky cap issue at triage in disgust. A loop mod with clean caps is a lot easier and pays the same per hour. MB is ready for a long break and this is likely the 1st shoe to drop.

Glad to hear you got someone on it. Otherwise there's going to be a fair amount of chassis/trany's/cabs available over time with great front and back plate options for a multi-channel DIY "hand-wired" Mark.
 
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