1978 Ampeg SVT Cap Replacement

[Jagmantom]

Does anyone know if there are upgraded replacement cap kits for a 1978 Ampeg 6650 SVT?

The only kit I can find is from Fliptops and they say the vales aren't original...

Also, how much should I expect for a tech to replace the caps? My local guy is quoting me $730 and the kit is only $104 so it seems high.

Any assistance would be greatly appreciated.

[Leo_Gnardo]

Does anyone know if there are upgraded replacement cap kits for a 1978 Ampeg 6650 SVT?

The only kit I can find is from Fliptops and they say the vales aren't original...

Also, how much should I expect for a tech to replace the caps? My local guy is quoting me $730 and the kit is only $104 so it seems high.

Any assistance would be greatly appreciated.

About some of the values not original, not surprising. I doubt you'd hear any difference if exact-value parts were used. Some were standard at the time the amp was made, others may have been custom made for Ampeg, not a problem when you're ordering 10,000 at a time. Fliptops had to have those 70+40+40 uF can caps custom made, that costs some $$$. $730 guesstimate for only filter cap replacement is sky high whether the caps are included or not. Granted, SVT are very time consuming to work on. Besides they typically have lots of other problems to solve beside filter caps - may be tech is taking that into account. I reckon that tech is telling you in a sidelong way, he'd rather be occupied with anything else than an SVT.

[gui_tarzan]

A lot of people that repair all sorts of things base their prices on difficulty of doing the job. Time = $$$

I have given very high quotes to avoid doing a particular job but I will tell the person their item is a PITA to work on which is why the price is so high.

[Enzo]

Does the amp work as it is, and you merely want to freshen the parts? Or is the amp not functional, and you want new caps as part of the repair? $730 seems very high to me. Whenever anyone gives me a high sounding estimate, I ask for them to break down the estimate. WHat is labor, what is parts. If they are quoting six hours of labor for a cap can change, I'd be suspect. Of course if you are in Manhattan, the labor rates will be double what they are here in Michigan. I suspect a can of green beans is also twice as much there, so...

Then again, Leo might be right. Wouldn't be the first tech to give a high estimate for something he'd prefer not to take in.

Values like 90uf and 70uf are not standard values. Parts they used to make 40-50 years ago are often no longer made. But 68uf and 82uf are both standard values that are close enough. 100uf is close enough to 90uf as to be the same. Can caps in those days had tolerances like -20/+80%. So a fairly close modern cap could actually be closer to the schematic than the original was when new.

[DrGonz78]

Where are you located? Perhaps there are techs here on the site nearby you that would take on the challenge for a more reasonable fee.

[Jagmantom]

Thanks everyone for the info. I'm in CT. The tech said the electrolytic caps in the output stage had leaked and were shorted. He said that caused the output stage to draw a lot of current which burnt out some resisters. He wanted $380 to just to change the two? output caps and the resisters. He also said that he should do the pre-amp caps as well when he was in the for another $350. I know a SVT is a pain to work on, but is the cap kit is $104 then $626 seems like a lot of labor to change 8 caps and 2 resistors.

[Enzo]

Yes it does. Why not seek out a "second opinion"?

[Leo_Gnardo]

An auto dealer will think nothing to charge you over a grand, closer to two grand, to fix up some widget that's gone wrong behind the dashboard. Five buck part, $120/hour to disassemble/reassemble your car. Plus tax. Indie mechanic, half to 3/4 that price.

SVT's aren't quite as difficult, you don't have to stand on your head while jamming your scalp into a filthy footwell to work on 'em while having debris fall into your eyes, nose & ears. But nearly so.

What I do in a case like this, is ask the customer for a DNX price, Do Not Exceed. Then I can go in, get amp or whatever improved to some extent, make a buck & keep the customer well, happier if not totally satisfied. And I don't take that DNX price as an excuse to spend every last penny, but it can happen with a difficult complex amp like an SVT.

FWIW I tried to help a poster on The Amp Garage a couple years ago, he was a bit east of Hartford and the tech close to the city. Tech liked to work on nice clean items like mixers, outboard gear, effects, video gear, like that. When asked for a guesstimate on the poster's funky amp, big price. The tech you spoke to - might be the same guy? Same attitude anyway. I don't remember how it worked out. Just for fun what town in CT? As Dr Gonz says, maybe someone here could help you.

[Jagmantom]

I just got my 1976 Ampeg SVT head back from service. The amp works now but doesn't have as much gain as it used to and lacks bass & "umph". He put in two 80-40-30-20 caps in the power supply,two 100/450 caps, and one 30/600 cap. Anyone have experience with this problem?

[Jazz P Bass]

Wholesale recapping of an amp can often lead to some unpleasant surprises.

Take it back to the tech & have him assure you that the amp is up to snuff.

[Jagmantom]

Thanks for the info. My friend is bringing over his 70's SVT head and we are going to compare them to see if the problem is in my head or in my head. The tech who worked on it said he would make it good. If not, Dennis at Central Jersey Music Service said he could get it back in shape. Apparently Dennis worked at Ampeg back in the day and was involved in the development of the SVT! Wish I knew that a month ago...

[Jazz P Bass]

Please keep in mind that the old filter caps may have given the amp a certain feel, tone, mojo............whatever.

By bringing the power supply into 'spec', it may now be a totally different amp.

(For better or for worse.)

[martin manning]

But more bass and "umpf" is what I'd expect from a power supply recap...

[Justin Thomas]

Maybe those replaced power supply caps were the ones that had drifted to the +80% that was typical spec on electrolytic caps of the era!

Justin

[The Dude]

Has the bias been checked since the caps were replaced?