Greetings - I'm new around this board, and looking for recommendations on buying caps for a 295 simul-class. Any dealers / distributors you can recommend ? The amp has very few hours on it - but it's been around since the late 90's I'd guess. It keeps popping the 1A fast acting fuses on the front panel. I'm assuming it's caps need changing. Also have a Studio pre-amp that will need some service... but the 295 comes first on the list. Will a simple Fluke cap test be first thing to do ? Should I trust that or- just take a bite and replace?
Need advice - Re-capping a 295 Simul-Class
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woodbutcher65
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Mesa stocks all the caps you need and they stock good quality parts. Just do that.
I had one of those amps. It was very good.
I had one of those amps. It was very good.
That was my hope as well, I found a couple of the spec caps on their site. I couldn't get them to add to my cart so I e-mailed Mesa and asked for a quote on basically all the power caps ( 22 Caps total ). They responded and said - if you can't put them in the cart then they are not available. I have made a list at antique electronics and am going to probably order there instead. Was hoping to keep it as factory spec ( and look )as possible. It's all good - but I'm going to test all tubes and maybe buy the the whole lot. So far it's running about 450.00 for the whole package. Tubes and caps. The amp is nearly mint looking and realistically probably has less than 50 hours on it's life. Built in 1987.
woodbutcher65
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If original spec caps are not available, you can get away with caps with a higher voltage rating, or caps that are slightly off value. A bit higher in value is better than going a bit low in value but usually there's no effect on the amp's performance if you undersize caps by as much as 25 percent. So if they don't have 220 uF caps in stock, but have 160s, that's close enough.
joey_truelove
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Wow, I'm about to recap a Fifty Fifty which is just a fraction of what you have on the table.
Most newer caps are shorter, which is a bonus these Sprague bgers being quite a handfull.
I'd look for some kind of brand caps, like the ones TAD sell as theirs, JJ, Philips or similar. I am probably going with TAD Golds, the Audio Caps being of too large a diameter.
Most newer caps are shorter, which is a bonus these Sprague bgers being quite a handfull.
I'd look for some kind of brand caps, like the ones TAD sell as theirs, JJ, Philips or similar. I am probably going with TAD Golds, the Audio Caps being of too large a diameter.
meesa_jarjar
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If your amp takes any 30uF caps, these are the ones Mike B recommended, I imagine other Sprague caps would be good for wherever you might need them if Mesa doesn't have what you need in stock:
https://tubedepot.com/products/sprague-atom-30f-500v
They are using Illinois 220uF/300V also if that helps.
https://tubedepot.com/products/sprague-atom-30f-500v
They are using Illinois 220uF/300V also if that helps.
Much appreciated. I had the tubes checked and just received an ESR meter to check the all the large caps. Everything seems to checking out pretty well so far.... seems the 30uF caps are hitting a bit higher at around 5 ohms. But, I'm still learning what to really look for. I only have one of the boards freed up and only checked half of the 220uF. There are a number of very low value ( like .022 and .1 orange drops that are reading open with the ESR meter. So , I'm not trusting that I'm checking those correctly. I'll probably try to score or borrow an actual capacitance meter before I go and buy and replace everything. I also have a Studio pre-amp that I'm going to get into shortly.
woodbutcher65
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Today, use Sprague Atoms whenever and wherever possible. They've always been premium quality and anybody who's recapped any number of Mesa amps knows full well that tomorrow a 45 year old Mark II might come in the door for recap and the original caps are still there, still doing their job, and are either Mallory or Sprague.
I'll use F&T, ARS, or Ruby, if necessary.
I've got a Mark IIB that needs recapping. It has all Sprague caps. No hum and no visible issues with the original caps, but they're due, being about 40 years old. However I'm not in a huge hurry. It's just not a time critical situation.
I'll use F&T, ARS, or Ruby, if necessary.
I've got a Mark IIB that needs recapping. It has all Sprague caps. No hum and no visible issues with the original caps, but they're due, being about 40 years old. However I'm not in a huge hurry. It's just not a time critical situation.
Just a quick follow up. The 295 was build in1987 . All tubes tested great, very stable and well matched. I took all the pains to allow removal of the boards - enough to test ESR on all electrolytics, they were all very low ESR, basically like new. So - being that the amp looks basically new and everything I could check tested well. I thought what the hell... shot a little D5 into the tubes sockets and proceeded to re-assemble. Popped new 1 a fuses in and fired it up......working just fine - minus a little low level squelching when working one level pot. The pot was cleaned before assembling - so my thought is that maybe there is an orange drop that's off on capacitance but works fine when the pot is settled. On to the Studio preamp repair. Appreciate the feedback. Maybe I'll start a new brain pick thread on that.
Theresa
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I recently was talking with Mike and aside from telling me that the "Blue Caps" are all but gone, they rarely need replacing. Chris at Boogie also said that in his 32 years there, he has never seen them needing to be replaced. (Just a PS here...) He did say that they are always indiscriminately swapped out by over-zealous techs. Leaky tubes are presumably the number one reason for scratchy sound according to early tech bulletins from Mesa Boogie. ("Scratchiness in other volume controls is usually caused by leaky tubes and not controls." from original Mark II C+ manual)
Thanks for confirmation. I was surprised how steady all the measurements were on all the electrolytics. I have just a little less knowledge needed to be dangerous, all this information is very helpful. I've always been sceptical of the " Just change the caps " advice. I re-capped my 79 Twin a couple of years ago. I happened to re-measure all the old ones. Only the paper oil caps measured a little high - even those were probably useable - all the Aluminum ones were still good.
woodbutcher65
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I'm by no means against replacing caps after they've reached the age of 30. Some lower quality brands won't make it that long.
But if you want to keep the original caps in service and they show no signs of being near the end of their life, by all means, keep them in, but do keep an eye on them. Watch for swollen vent seals, over-shrunken shrink wrap labels, high ESR, hum, crackling, and of course, capacitance values that are significantly out of spec.
But if you want to keep the original caps in service and they show no signs of being near the end of their life, by all means, keep them in, but do keep an eye on them. Watch for swollen vent seals, over-shrunken shrink wrap labels, high ESR, hum, crackling, and of course, capacitance values that are significantly out of spec.
The one I bought is pretty low cost. It's a Sinestek MESR100. You can find it on e-bay and amazon etc. There is another that is pretty low cost that measures capacitance as well. I wish I spent a little more for that one : it's the Peak Electronic ESR70. A Google search for ESR meter will get you a number of options. There's some you tubes on using them that's pretty helpful.
woodbutcher65
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You can't check ESR with the capacitors in circuit. That doesn't work because the parallel resistances in circuit around the capacitors are going to greatly alter the readings.
To check a capacitor properly it needs to be fully removed from the circuit and then tested.
The reason to check the coupling capacitors is "when it's misbehaving". If the amp is running normally, there's probably no reason to worry about checking the coupling and bypass capacitors.
Just a couple weeks ago I got a Mark III in for a checkout and it was red plating two tubes. I found a shorted .1 uF orange drop and replaced the pair with Panasonic film caps. Oddly, the orange drops were 400 volt rated, and in that circuit they'd never see more than bias voltage, so even 100 volt rated parts should be good in that application. I put in 250 volt rated parts because I have them. And it runs fine.
To check a capacitor properly it needs to be fully removed from the circuit and then tested.
The reason to check the coupling capacitors is "when it's misbehaving". If the amp is running normally, there's probably no reason to worry about checking the coupling and bypass capacitors.
Just a couple weeks ago I got a Mark III in for a checkout and it was red plating two tubes. I found a shorted .1 uF orange drop and replaced the pair with Panasonic film caps. Oddly, the orange drops were 400 volt rated, and in that circuit they'd never see more than bias voltage, so even 100 volt rated parts should be good in that application. I put in 250 volt rated parts because I have them. And it runs fine.
Ty WB! Now I'm confused. While shopping for one, the one mentioned says in circuit testing.
. the Orange drops need to be lifted and tested with an ESR meter just as if you were testing a resistor?
