NAD: Mesa Mark IV - service

Sprague 10,000 big brown caps. They may emit residue all over the board and make an awful mess that Mike B says is much more labor intensive that just replacing them. And congrats, one of the best amps EVAR.
 
Congrats!

Take the amp out and check the dates on the caps first. Should be a two digit code.
Someone may have already had them replaced before you got the amp.

My Mark III came with original caps from 85 and 87. Replaced them with a 2020 set.
 
My Mark IVb is from '96 and I believe I have those brown caps in mine... They look good to me and the amp sounds great, you think i should still send it in for a re-cap?? Or can I wait a few years still, cause I really don't have the cash do get it serviced.
 
I believe only the early "A" amps have those caps. I seem to Recall Mike telling me that when I spoke to him before getting my amp overhauled.
 
I have a B and mine didnt have the Brown cap but it did have some that were on their way out(just started leaking.) I personally would send it in for piece of mind. It really isnt that expensive. Now when it comes time to send it in the cost will go up. It's an old amp, some maintenance now will go a long way.

BTW the price really isnt that bad. I think I paid 250 all in.
 
Chris6870 said:
I believe only the early "A" amps have those caps. I seem to Recall Mike telling me that when I spoke to him before getting my amp overhauled.
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That's what I thought too, but when I opened my amp up there they were, two brown caps exactly as described, so IDK... My Mark IV is one of those transitional amps too, as in it has some cosmetic qualities of the A revision (attached power cord) and is sometimes called the IVa/b.
 
anomaly said:
That's what I thought too, but when I opened my amp up there they were, two brown caps exactly as described, so IDK... My Mark IV is one of those transitional amps too, as in it has some cosmetic qualities of the A revision (attached power cord) and is sometimes called the IVa/b.
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I would wait till you have the cash to get the caps changed. I mean they are well over 20 years old, but it’s not like it’s an urgent thing. Worse case they explode and you have to pay more.

I have a 1990 mark Iva and as of last year the caps were still going. I ordered them, but still haven’t been able to clear my bench to get to the project. I miss that amp, need to find a way to work it in. Spring is always a flood of amp repairs and this year is not different.
 
anomaly said:
That's what I thought too, but when I opened my amp up there they were, two brown caps exactly as described, so IDK... My Mark IV is one of those transitional amps too, as in it has some cosmetic qualities of the A revision (attached power cord) and is sometimes called the IVa/b.
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I was wondering about the one I recently got. I am new to Mark IV. I thought mine was a version A because of attached power cord. But I saw on the Boogie Board Mark IV thread that version B starts at SN 6000. Mine is SN 7xxx. So is mine a A or B how else to do u tell? Maybe transitional model? Thanks
 
Look at the effects loop - the A models have two, one is normal and one is switchable, and they are both mono. The Bs have one loop, with left and right returns
 
Mike B told me if the caps blow the cost to clean up the amp and get them replaced was around $600! Yikes. He said when the caps blow they make a huge mess all over the board which is a pain in the ass to clean. And that $600 probably doesn’t cover the shipping to and from Cali from wherever you are.
 
Also came with the original combo shell. Which it’s going back into until I buy a new headshell. The tech is giving it TLC and replacing the pots that’s broken too :)
 

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For reference, I contacted Mike B about my IV B, serial 12xxx and he said: "Those are not the nasty SPRAGUE timer bomb caps, they are the early version Illinois caps we used. I have seen no disasters but I do pull them to replace and usually find a touch of leakage on about 20 % (?) of them."

Edit - here is my Mark IV with the Illinois caps:
 
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Meeotch said:
For reference, I contacted Mike B about my IV B, serial 12xxx and he said: "Those are not the nasty SPRAGUE timer bomb caps, they are the early version Illinois caps we used. I have seen no disasters but I do pull them to replace and usually find a touch of leakage on about 20 % (?) of them."

Hopefully this photo can help.
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So is that a photo of the bad caps or not ?

Other than the color how can you tell if they are the caps that need to be replaced ?
 
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