Supro rebuild... need some recap advice...

[cdc3jj]

So I have a little boost of confidence after finishing a 5e3. I think I'm going to try to get this old Supro up and running again. I believe it's a "Surpreme 1600" from the catalog scans a fellow memeber sent me a while back.

I labeled a couple of the pics with cap values and can values. I'm going to use individual caps on a terminal strip rather than trying to track down replacement cans. But I don't how to remove the cans. They are riveted down. I don't want to cut it out but I don't know how else to see what is inside (if I even need to that is).

I also don't know what kind of caps I need. I've looked on several sites (aes, weber, digi, etc) but I don't know what I'm looking for in terms of type. I know the values but thats it. If any one could clue me in or point me towards a online tutorial of some kind I'd really appreciate it.

The amp powers up and when the volume is maxed I can hear a very faint signal coming through. I know it needs a cap job so I'm starting there. Here are some pics that show what we're dealing with. Thanks for everything thus far. Can't wait to get this little baby going too.

[ThermionicScott]

That's a cool specimen! You could use Orange Drops or whatever for the coupling caps, regular electrolytic 25uF/50V that you would for a Fender cathode. I think that you should leave the cap cans in place for looks and tuck individual electrolytics inside the chassis. Heck, some radial-lead caps might work best in some of those spots!

- Scott

[TNO]

I've re-capped one of those. Leave the old can in and add a terminal strip or two to support the new caps. The original values were three 10uf but you really want the first cap (to the rectifier) to be at least a 20uf for tighter bass and reduced hum. Don't go over 30uf with a 5y3. You need SMALL filter caps to fit in that chassis. Nichicons are pretty nice but still a little large. The electrolytics from WeberVST fit well and are very cheap. For coupling caps I'd use Sozos/Jupiters/Mojo Dijons. All those are nice caps, better than Orange Drops or Mallory 150s, and are pretty close to the caps used originally.

[cdc3jj]

Cool, I found all the stuff on webers site. I was told the .05 on the right side (in the picture) that sits parallel to the .02 is called the "death cap" and shouldn't be replaced because it redirects the electricity into the chassis if there's a failure in the circuit. Was that your experience?

[cdc3jj]

I'm thinking this is what I need on coupling caps...

3x .022
1x .047 (or two depending on that whole death cap thing)
1x .01
Plus the big electrolytic thats 25mfd/25vdc.

Then there are two 10mfd's in one can and a 30mfd in the other. So would I replace one of the 10uf's with a 20uf or a 22uf?

Those are all electrolytic right?

And is it better to go higher or lower on the 30uf? Weber has a 27uf or a 33uf (if that's even the right kind of cap). Or is it better to put three 10's together?

Found this schematic online. Not sure it's the right one... several of the values are different.

Thanks for the help. This should answer most of my questions.

[cdc3jj]

Here's the link to that schematic, I guess it didn't post.

http://www.valcopages.com/Schematics/Supro_1600.pdf

[FiddlinJim]

I worked on its little brother and I started with a "bundle" of axial capacitors, but ended up drilling out the rivets, removing a little of material from the chassis, and installing a new cap can. See the thread: http://www.tdpri.com/forum/shock-bro...ming-oahu.html

TAD and F&T capacitors are great to work with. They're very small compared to Sprague Atoms and some others.

The little guy sounds good, but I get an annoying hum that I haven't been able to get rid of. At any volume, the hum gets buried, so I guess I just can't stop playing.

[ThermionicScott]

The schematic calls for a 40uF in the first position, so I'd go for that. After the plates, you don't need all that much. You could use 16uF-22uF for the other two, but light filtering might be part of the charm of this amp, I don't know from experience.

It's really easy to put on the "engineer hat" when looking at these schematics, so it's important to reign in that tendency until you've heard the amp as it was originally intended to sound, I think.

- Scott

[pbenn]

There's a Supro feature in the new Vintage Guitar magazine. Billy Sheehan cover, Feb 2010.

[TNO]

The stock values used in your amp are perfect. Make sure the electrolytic caps are oriented the right way.

[cdc3jj]

Fun starts tonight... I got my bag of goodies from weber saturday and the wife came home in a mood so I'll be hiding in the cave this evening. One quick question... Is the "foil side" the positive or negitive? The old caps in the amp have a black band at one end and are labeled "outside foil."

[ThermionicScott]

The banded end is the outside: http://www.aikenamps.com/OutsideFoil.htm

- Scott

[cdc3jj]

New pics and new questions... On the cap can rebuilds, on the one with two caps in it, will they be wired like in the picture? On the one with a single cap does the negitive go to a ground or somewhere else? Posted pics of the bottoms of the caps. Also how do you change from a two prong to three prong? Just an extra ground? Thanks for the help...

[TNO]

Negative goes to ground and ideally you want to separate the grounds of the 30uf from the two 10s to reduce hum. That chassis is painted so you need to take care to get a good, solid ground connection.

[cdc3jj]

Cool... So I realized that I ordered a 40uf instead of a 30uf, which is what the one can contains. Will that cause issues? Should I get a 30uf or will the 40 be ok? The schematic says 40 but wanted to check before applying electricity.

[ThermionicScott]

Originally Posted by cdc3jj

Cool... So I realized that I ordered a 40uf instead of a 30uf, which is what the one can contains. Will that cause issues? Should I get a 30uf or will the 40 be ok? The schematic says 40 but wanted to check before applying electricity.

Either will be fine.

[cdc3jj]

Finished... Power on... Killer tone!! And it's quiet too. I expected a hiss or hum or something. Nada. I half expected the switch to shock me or something to catch fire after the trouble I had with my 5e3.

It's still pretty low volume, (at least at half way. Wife is sleeping and even though my inner Neil Young was itching to come out I restrained) and the 6J7 tube with a big fat wire coming out of the top is microphonic. it's got that annoying pinging sound when I tapped on it. Where could I find one of those? Or should I somehow rewire it for a 12ax7 or similar? Thanks for the help