Have a mesa mark 1 I bought in 1977. Have not played through it much in the last few years because I started having electronics problems with it. Am very familiar with tube problems and I don't believe that's the issue. Replaced all tubes a while ago and no change in issues. Major problems are noise and inconsistent volume. Have heard the caps need to be changed because they breakdown after twenty years. Anybody have any suggestions on who has experience repairing a boogie this old. Have the schematics, fentron was replaced years ago when they were no longer available per R. Smith's instructions. Serial number is A475. Due to it's age only want to trust it to someone who knows this vintage boogie well.
mesa boogie mark 1
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Filter caps do deteriorate after about 10 years,it is even faster if the amp is not used for a long period of time.They dry out faster if they do not get current thru them regularly.You say you havent used it in a few years.I would bet filter caps are 99% of the problem.They supply the power your amp needs to function properly,if they dont do their job efficiently,your amp cant do its job.Change them first.Any competent tech can do the job,its just an amp,nothing magical about it,and I would insist on the best quality caps,I use F&T and Sprague only.The Illinois and other asian caps suck,avoid them like the plague.
Whoopysnorp
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What's so bad about Illinois caps? I recently replaced the new Sprague Atoms in my Studio .22 with a new set of equivalents from Illinois Capacitors--the reason why is convoluted but irrelevant--and it sounds just as good now as it did before.
jonarobb
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Whoopysnorp said:
The Illinois Caps have a bad rap because their quality control sank when they went overseas in 2002. Electrolytic caps were literally exploding in amps left and right. They immediately stabilized production and currently their caps are excellent. The damage was done and folks are still scared to use em'. They are just as good as Sprague and in some instances superior to Sprague.
Significant tests have been conducted by the cats over at alt.guitar.....
Here's the blurb from them:
"When I measured "dialectric absorption" (a measurement related to the ability of a cap to recharge itself on its own...after discharge and removal of supply), ALL caps measured a healthy scant 4%.
In general, the Illinois caps are made to tighter tolerances. Read and weep! Illinois caps generally had lower S/Ds. Values were closer to their rated values. Still, both mfr's caps are HUGELY more precise than what was available 35 years ago where a tolerance of -50%/+75% was not uncommon. Illinois' average tested at an amazing 1% for the 100uF and 12% for the 22uF, Sprague's was 8% for the 100uF and 16% for the 20uF.
ESR for the 100uF was significantly lower for the Illinois, but Sprague had the edge for the 22 (20) uF cap. In all cases, the values fell within acceptable limits.
These tests are obviously non-musical. I didn't listen to 24 filter caps, just took some reliable and relevant numbers. Also, there's no indication on what will happen after 10 years in service (anybody want to do THAT test?)
But hopefully, this will put to rest the myth that Illinois caps are unsuitable crap. At least according to what I can measure, they're as good if not better than the Spragues (at least at the 100uf/350V value). Admittedly, ESR and leakage were higher for the Illinois than Sprague at 22uF, but they're still within normal limits of acceptability.
That said, I still prefer the Spragues for applications where lead length and strength are important, and Illinois where space is at a premium."
Whoopysnorp
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That's a relief. The going rate on 450V 30uf Sprague Atoms is truly outrageous.
If Illinois caps are good enough for you,then thats fine.I base my statements on 30 years of experience.I did my first cap job back in the mid-late '70's.I am not an engineer,so ESR and tolerances mean nothing to me.In fact tolerances mean nothing,or very little when it comes to filter caps,and guitar amps in general.Every other component is +/- 10%.So it really dont matter if your 100uf filter reads 96uf or 110uf.In my experience,the F&T and Sprague do sound better and give a tighter response particularly in the bass.When I do a cap job,I give the guarantee that if your caps are over ten years old,even if they dont seem to be bad i.e. noise power level,if I put the new ones in and you dont notice an improvement,I put the old ones back and you dont pay.I have never put the old ones back.In fact,in the last year and a half I have done over 60 Boogie amps,many thanks to one client I picked up here,based on this statement.Most of those didnt even think the caps were bad,many were even told by MB at Mesa they didnt need new caps.Now I aint saying I know more than him,but in this regard he is dead wrong.Every one of those guys were blown away by their "new" amp.I recently had a guy bring me a Blues Deluxe with a blown preamp filter cap.The amp was less than a year old.I suggested he take all the crap Illinois out and change them for F&T's,again with my usual guarantee,he is now a beleiver.Like I said if you use the Illinois or any of the asian productions and cant hear a difference,then for you,it doesnt matter.If you cant hear a difference,there is no difference.I would never use or recomend anything but F&T or Sprague.Your power supply is the heart and soul of your tube gear,why cheap it?jonarobb said:Whoopysnorp said:
The Illinois Caps have a bad rap because their quality control sank when they went overseas in 2002. Electrolytic caps were literally exploding in amps left and right. They immediately stabilized production and currently their caps are excellent. The damage was done and folks are still scared to use em'. They are just as good as Sprague and in some instances superior to Sprague.
Significant tests have been conducted by the cats over at alt.guitar.....
Here's the blurb from them:
"When I measured "dialectric absorption" (a measurement related to the ability of a cap to recharge itself on its own...after discharge and removal of supply), ALL caps measured a healthy scant 4%.
In general, the Illinois caps are made to tighter tolerances. Read and weep! Illinois caps generally had lower S/Ds. Values were closer to their rated values. Still, both mfr's caps are HUGELY more precise than what was available 35 years ago where a tolerance of -50%/+75% was not uncommon. Illinois' average tested at an amazing 1% for the 100uF and 12% for the 22uF, Sprague's was 8% for the 100uF and 16% for the 20uF.
ESR for the 100uF was significantly lower for the Illinois, but Sprague had the edge for the 22 (20) uF cap. In all cases, the values fell within acceptable limits.
These tests are obviously non-musical. I didn't listen to 24 filter caps, just took some reliable and relevant numbers. Also, there's no indication on what will happen after 10 years in service (anybody want to do THAT test?)
But hopefully, this will put to rest the myth that Illinois caps are unsuitable crap. At least according to what I can measure, they're as good if not better than the Spragues (at least at the 100uf/350V value). Admittedly, ESR and leakage were higher for the Illinois than Sprague at 22uF, but they're still within normal limits of acceptability.
That said, I still prefer the Spragues for applications where lead length and strength are important, and Illinois where space is at a premium."
jonarobb
Well-known member
I hear ya'. I've also been working on Boogies, and other tube gear for quite some time. I don't have 30 years experience. I have enough to know that the Sprague name was sold off years ago to international conglomerate Vishay. Point is, Vishay owns the Sprague name and farms it out to whoever can make them the cheapest and still meet spec. Unless you're buying in bulk from United Chemicon in North Carolina, like Mesa, or Barker Microfareds in Virginia, yours, mine and everyone else's Sprague Atom TVA's are made overseas. If your Spragues have an H or an L in the production code then they are the last batch to be made in the USA as far as I know.
I do however agree partially. I like Sprague in the power section. And most of my clients ask for em' by name so I keep fully stocked. But IC, F&T, Xicon....all well within spec and very durable.
I do however agree partially. I like Sprague in the power section. And most of my clients ask for em' by name so I keep fully stocked. But IC, F&T, Xicon....all well within spec and very durable.
Okay.I'll give you the Spragues have fallen off somewhat of late,but I still find them better than the IC's,Illinois,Xicon etc.In fact these are the only ones I've ever seen explode/fail prematurely.I have been leaning more to the F&T's lately,mainly due to the price of the Spragues.And either of these always gives a marked improvement in the amps response over the IC's etc.,especially after a couple of years.Hey,we all have our reasons for what we like,and like I say,if they work for you....Could be a little bit of"you cant teach an old dog......"
