Mrak III cap question - Mandatory replacement or not?

[herrball]

So I picked up a MK III blue stripe combo just before xmas with the original EV12and 1 FS for $600...not a bad deal. But I'm thinking it may need a cap job due to the age so here's the question:

The amp is sounding a bit dull so outside of a tube job ( which I haven't done yet...I know this will make a huge difference), I spoke with my local authorized Mesa tech and he said let's see what the new tubes bring because you may not need a cap job. According to this tech, Mesa used hermeticaly sealed caps for a while and they don't dry out so do not need to be replaced. He would take a look and determine once the chassis is open. Specific runs/stripes used these.
I certainly understand the need for new tubes; its like fresh strings. But in my surfing on this board, all I ever see is that the cap job is a mandatory for original MKs that haven't been touched.

Anyone know anything about this? Thanks for any help.....

 

[stokes]

Hermetically sealed caps?????They never need to be replaced??Where can I get some?If that amp has the original caps,you will definately notice an improvement with fresh,good quality caps.By good quality,I mean Sprague or F&T.Of course,the tubes go without saying.

 

[av8or3]

The 30uf caps in that amp are probably epoxy sealed (hard,red, shiney epoxy) as opposed to the rubber seals you see on most caps. These are what your tech is referring to. Mike B @ Mesa has told me that he hasn't seen a problem with them so he dosen't replace them routinely, only when he finds one thats a problem. I know this to be true because he did a cap job for me on my Simulclass C+ and these caps were not replaced. The big 220uf filter caps are not sealed in this way and should be replaced because they are old and most certainly are not operating to spec.
Ed Morgan (Boogiebabies on this forum) performed an excellant cap job for me on my 60 Watt C+ along with other repairs that were found to be necessary and he DID replace those 30uf caps. Had I understood more about what Mike was doing, I probably would have asked him to replace the 30uf caps anyway, but I didn't. Both amps run fine BTW and were different, better sounding amps when plugged in on their return.
Jim

 

[stokes]

Those 30uf caps are just Sprague Atoms specifically packaged for Mesa with their own shrink wrap label,nothing more.They are a better quality than those crap Illinois 220uf's,which,despite the name are not American made.They should be replaced like any other cap,Boogiebabies is indeed a knowledgeable and very experienced tech when it comes to Mesa amps and that is why he changed those caps.I myself have had quite a few amps bought to me after Mike B. told the owner those caps didnt need to be changed and in every case the owner was pleased with the results and confused at Mike B's point of view.In a great many cases I have people come to me thinking their amp sounds fine,which it does,but after convincing them to change the old caps they are floored by the improvement they didnt think their amp needed.If your caps are over 10 years old,replace them,you wont be disappointed.But as always I have to say this only stands if you are going to use good quality replacements,I wont use any but Sprague or F&T.I think I recall a thread where Boogiebabies mentions another brand he's found that equals them,and I would have to assume they do,I just havent found a need to try them yet,I dont recall the name,maybe BB will chime in here.

 

[herrball]

Thanks for the quick response guys. This is exactly what I was looking for in terms of info. I'm going to do the updates in stages starting with the tubes and then the cap job in late Feb. ( I think it will be somewhere around $200, maybe a little more. at least that's what the tech said) I know the tubes will wake it up and the cap job will bring it back to that tone I love.

I'll post an update once the tubes are in.

Thanks again guys......

randy

 

[Restless Rocks]

As it happens I live about 30 miles from the Barker Microfarad Inc. factory. And only 4 miles from the United Chemi-con plant (formerly Sprague). Barker owns all the exact old machinery from the Sprague plant that produced the familiar orange Atoms for many years. I also managed the dept. in a small electronics manufacturing plant (General Assembly Corp.)nearby where Barker subcontracts the constuction of the end caps for the high voltage electrolytics. I also have used the "BMI" caps with the Mesa labeling and am convinced they are of the quality you'd expect from genuine old school American manufacture. I must also point out that I have never seen a Mesa labeled electrolytic catastrophicly fail. ie. as an open or short circuit. I have recapped many by the request of the owner but only a couple that showed to be leaking (electrically).

 

[fdesalvo]

Speaking of refreshing the filters, it seems as though it wouldn't be that big of a deal to do yourself, provided the caps can be removed with the board in place. Anyone know if removing the circuit board is required for this?

BTW, there are better caps out there than the Sprague Atoms. I've seen them dissected, revealing a smaller cap within a larger package. The Illinois brand isn't top-shelf, but they are fine caps nevertheless. The only time I've seen one fail is when I "accidentally" applied AC to one haha. Lot's of amp builders, even Doug Hoffman, swear by them. I've used them without issue in some of my homebrews. I've also used F&Ts in my latest and I absolutely love them. Not to mention, the black packaging looks sick.

Just my .02uf

 

[av8or3]

Speaking of refreshing the filters, it seems as though it wouldn't be that big of a deal to do yourself, provided the caps can be removed with the board in place. Anyone know if removing the circuit board is required for this?
Just my .02uf

The boards need to be removed for this.
Jim

 

[fdesalvo]

Thanks, Jim.

 

[stokes]

The boards dont need to be removed,just clip the lead close to the cap so you leave enough lead on the board so you can connect a heat sink to insulate the board from the heat of your iron,those traces can be quite fragile.

 

[herrball]

my soldering skills stink for the simple stuff like swapping pickups so I'll leave the cap job to a pro. ;-)

Oh, here's an interesting thing about the amp......along the way someone replaced the 3-way toggle with a 2-way so the EQ can only be on auto or on; no off completely. I suspect it was done out of hurrying through the job and a the previous owner not caring. Not an issue for me right now since I use the EQ on auto for leads anyway but when I have the guy open it up for the caps I'll have him replace the toggle for a 3-way.

So here's a word to the wise on eBay purchase.....check EVERYTHING!. I missed checking the toggle as I never dreamed it would be a 2-way. live and learn.

 

[stokes]

"BTW, there are better caps out there than the Sprague Atoms. I've seen them dissected, revealing a smaller cap within a larger package"
I am pretty sure that "smaller cap within a larger cap" thing is either a myth,or some dubious attempt at selling some cheap knock-off of the Sprague.I saw that post where someone posted a pic of the cap in question so I dissected a 20+ yr old idenntical cap and a brand new one myself,and they were both the same,no smaller cap inside the bigger package.Dont believe everything you see on the 'net.Illinois are not "fine" in my experience.Lately I've seen a lot of new Fenders with bad IC's less than a year old.

 

[Boogiebabies]

I get the BMI caps from Mesa. They are cheaper and made in the USA.

For MK II's, I unsolder the standby wire that runs across the board, flip it over and remove the Red/Red/Red-Blue
HV taps. They snap after flipping the board two or three times anyway. I remove the board because the bias, EQ supply
and all other voltage supplies are close to the resistor leads. The two dropper resistors can move around as well.
Once out, the new caps can be fed through the holes, bent at the ends and soldered. For 60/100's and Simuls, there are
no holes for the bottom caps so you need to bend the leads at an angle where the caps rest on the board.

For the MK III, cut the caps out and carefully heat the joint and pull the old leads out. The power supply board is very easy
and can be removed in 3 seconds. Be careful on the three 30uf's on the main PCB. Try to get one out intact to measure the lead length
so you don't short the new one positive side to the chassis. In the tight area's with a lot of wiring, I cover the wires with masking tape to
prevent the side of the iron from burning them. You may find yourself at some weird angles and I HATE burnt wiring.

 

[fdesalvo]

"BTW, there are better caps out there than the Sprague Atoms. I've seen them dissected, revealing a smaller cap within a larger package"
I am pretty sure that "smaller cap within a larger cap" thing is either a myth,or some dubious attempt at selling some cheap knock-off of the Sprague.I saw that post where someone posted a pic of the cap in question so I dissected a 20+ yr old idenntical cap and a brand new one myself,and they were both the same,no smaller cap inside the bigger package.Dont believe everything you see on the 'net.Illinois are not "fine" in my experience.Lately I've seen a lot of new Fenders with bad IC's less than a year old.

Thanks, Stokes.

 

[boogiemon]

Anybody ever put these in their boogie?

http://www.audience-av.com/capacitors/a_description.php

think it would make a difference?

Speaking of refreshing the filters, it seems as though it wouldn't be that big of a deal to do yourself, provided the caps can be removed with the board in place. Anyone know if removing the circuit board is required for this?

BTW, there are better caps out there than the Sprague Atoms. I've seen them dissected, revealing a smaller cap within a larger package. The Illinois brand isn't top-shelf, but they are fine caps nevertheless. The only time I've seen one fail is when I "accidentally" applied AC to one haha. Lot's of amp builders, even Doug Hoffman, swear by them. I've used them without issue in some of my homebrews. I've also used F&Ts in my latest and I absolutely love them. Not to mention, the black packaging looks sick.

Just my .02uf

 

[stokes]

Those auricaps are overpriced caps aimed at the hi-fi guys.A lot of hoodoo,if you ask me.I have never tried them,but someone I know,yeah,I know-another rumor,said they did nothing for his BF Deluxe.Maybe good for sound reproduction in a hi-fi,but guitar amps are a different animal.

 

[stokes]

Look at the price of those auricaps.I have never used them,but any talk of them in guitar amp circles doesnt indicate anything to justify that price.They are intended for hi-fi applications,but hey,tone is subjective,you might like them,but I cant see paying $15+ for a cap.

 

[fdesalvo]

Sollen/Auricap caps sound like crap in the preamp of a guitar amp- very sterile. For a power supply I can't see how they'd change the tone for better over the stock Mesa caps.

 

[stokes]

Sollen/Auricap caps sound like crap in the preamp of a guitar amp- very sterile. For a power supply I can't see how they'd change the tone for better over the stock Mesa caps.

Not surprising,they claim to be "sonically transparent",in my experience "transparent" always translates to cold,sterile.I've read about using non-electrolytics in a power supply,the only advantage being that they wont wear out,I suspect they would make things "transparent" or cold and sterile.I've never been interested enough in finding out to spring for the extra $$$.R.G Keane wrote a favorable article on it in P.G magazine a while back.

 

[glip22]

I get the BMI caps from Mesa. They are cheaper and made in the USA.

For MK II's, I unsolder the standby wire that runs across the board, flip it over and remove the Red/Red/Red-Blue
HV taps. They snap after flipping the board two or three times anyway. I remove the board because the bias, EQ supply
and all other voltage supplies are close to the resistor leads. The two dropper resistors can move around as well.
Once out, the new caps can be fed through the holes, bent at the ends and soldered. For 60/100's and Simuls, there are
no holes for the bottom caps so you need to bend the leads at an angle where the caps rest on the board.

For the MK III, cut the caps out and carefully heat the joint and pull the old leads out. The power supply board is very easy
and can be removed in 3 seconds. Be careful on the three 30uf's on the main PCB. Try to get one out intact to measure the lead length
so you don't short the new one positive side to the chassis. In the tight area's with a lot of wiring, I cover the wires with masking tape to
prevent the side of the iron from burning them. You may find yourself at some weird angles and I HATE burnt wiring.

Any way you can advise on a MK IV. I have the power board lifted. I only had to desolder one wire going to the switch. Getting to the underside of the 3 500V 30uf and bias caps looks challenging.Thanks