Ampeg SVT 6 Pro One of the 5600uf 80 v caps blew, power surge

[Smitty02]

Hi guys This my first time post Love this forum use it all the time ..So I got a ampeg svt 6 pro a friend brought me to look at and 1 of the 5600uf 80v filter caps look like mt st helens.. Not that bad but she blew for sure. I was told it took a power surge how ever it still powers up and works I am looking into loud tech for a replacement cap but was wondering if anybody had any info that might be helpful as i am going to replace the cap, anything else i should be checking? I could use a schemo and layout and Any info from you guys if anybody would care to share one. I am flying blind other than the cap it all looks good no damage at all that I can see visably thanks ahead of time, I know you guys are real good as i follow your forum.

[Enzo]

So replace the cap and see if it works OK. If it works, stop fixing it.

Mouser has 5600uf 80v caps in stock, four varieties. One of them is a 105 degree type insteaqd of the usual 85 degrees. All that means is it should last longer in the heat of the amplifier. Look on your old cap, does it say 85 or 105 degrees? Moiuser has them as low as $5, the 105 is about $7.

I doubt there is anything special about the cap, I assume the lead spacing is 10mm? Most of the Mouser ones are 45mm tall, though one is only 35mm, in case there is low clearance.

I am a Loud service center, and I even would be looking to Mouser or similar supplier, frankly.

[soundguruman]

Its hard to say if it really was a surge that made it blow, or just a defective capacitor...but if it was a real surge, one might expect other stuff to be blown or damaged as well...

[52 Bill]

Welcome to the place.

My first question would be why did your friend ask you to look at it, was it blowing fuses, overheating, etc. or did he just want it checked over because of the "power surge"?

I'm with Enzo on this one, replace the cap, check/clean the jacks and pots, check it out and if all is well call it a day.

[Smitty02]

Thanks for the welcome Bill. Yes I feel the same new cap see how it goes from there, was hoping I might be able to get a schematic and run some voltage checks. They brought me several amps from the backline and a stereo receiver mainly fuses except for the bass amp a fender Rumble 100 the one of the cement resistors and 2 of the diodes fell on the floor as I pulled the chassis. the traces looked burned so i made jumpers. That was the only one other than the ampeg that had any real damage. I played the rumble for awhile and it was thumpin and pumpin like a rumble should, but the owner says it seems quieter now ?? I dont think nor did I feel it was not up to par now or I would have pulled it apart again and run some voltages. They also brought me a Yamaha EM1800 powered mixer that needs new jacks on the aux board, they look just like fender 4 pin mono except for the a metal face plate that is grounded to the board, any ideas for a old yamaha as to the correct parts being available? If I order for mouser Id like to try and get all i need I am also looking for a 24mm 500k lin dual gang pot with a 3/8 bushing for a old ernie ball stereo volume pan pedal mistakenly bought one with not enough thread to make it through the thick aluminum they are made of, also has to be a solid shaft. Love the forum guys ive been following it for a long time picking up alot of info from you guys Finally decided to join yous. I am a novice I know but am pretty good at fixing up pretty much anything that comes my way. As I am disabled i have to do all i can to help support my family plus it makes me feel useful and productive again well some it aint like i make a living for us I wheel and deal and sell stuff to make a buck. Thanks for your insights guys

[J M Fahey]

Welcome.
Agree with above suggestions: clearly you *did* have a power surge, but if replacing the obvious leaky caps, maybe some overheated resistor, etc makes the amps work normally, that's it.
"The amp was louder before" is a typical creation of the Musician's mind; SS stuff basically either works or dies.
Only possibility is if you replaced some resistor with the wrong value, check that, but otherwise ... let it fly.

[52 Bill]

I'm not sure about the Yamaha jacks but everything else is available, unfortunately not all from the same supplier.

[Smitty02]

Yeah.. I know. I was hoping you guys may have a super supplier I didnt know about LOL I get tired of ordering from all over the place... Thanks Bill JM and enzo and guruman for your advice

[Axtman]

Since there are 2 large filter capacitors should he replace both of them or just the blown one? If he just replaces only 1 filter capacitor will that somehow make the output out of balance? We he then get different voltages or ripple on the different rails? Thanks!

[Enzo]

Out of balance? No. Imagine you have two PA speakers with a #16 speaker cord running to each. One cord is damaged so you replace it with a #14 because they are out of #16. Would you fear a lack of balance? If a cap does its job, it does its job.

[mozwell]

i hope this helps