Help with capacitor rating codes

[Gioanpj]

Hello,

I'm working on a Sunn Concert Bass head. There are two electrolytic capacitors which have a marking code I am unfamiliar with and can't find anything about.

Both capacitors are from the company STM.

Capacitor 1 says "1,5 63v". Obviously it's 63v. I'm assuming this means 1 + 5 zeroes tacked on, but I'm not sure if it's PF or UF. My hunch is that this capacitor is 1uf, but I wanted to be sure.

Capacitor 2 says "31c2/50". So, I'm assuming it is 50v. But I'm not sure about the capacitance rating.

Any help would be much appreciated.

Thanks!

[tedmich]

maybe find them on the schematic?

http://www.prowessamplifiers.com/sch...oncertbass.pdf

lots more info here
http://music-electronics-forum.com/a...rvice-info.pdf

[Gioanpj]

Thanks Tedmich,

I found the capacitors in the schematics you posted.

[Chuck H]

Thanks Tedmich,

I found the capacitors in the schematics you posted.

If the schematic posted the values.?. Could you clue the rest of us in on what those codes mean Those marking wouldn't be on the schem and we aren't aware of the part locations so we (at the forum) might still like to know the answer to this mystery.

[Gioanpj]

If the schematic posted the values.?. Could you clue the rest of us in on what those codes mean Those marking wouldn't be on the schem and we aren't aware of the part locations so we (at the forum) might still like to know the answer to this mystery.

The capacitors in question were "c105" and "c124." C105 was the capacitor that had the markings "1,5 63v." Now, on the schematic it says this is a 1.6uf, 25v capacitor. Either, someone replaced the caps in the head I had at some point (there was definitely some hack work done), or perhaps the head I have has a slightly different circuit. Either way, it is acceptable to replace capacitors with higher voltage ratings than needed, but never lower. You can often get away with going with a slightly higher capacitance rating depending on what the capacitor's function is in the circuit.

C124 is a 2.2uf, 50v capacitor. That was the one with the capacitor that had the markings "31c2/50."

Now, whether that is the actual capacitance or markings of the capacitors in the circuit is a different question.

[caliskan]

Gioanpj, using a capacitor with different capacitance values is not a very common practice when it comes to mass produced PCBs. This is a cleat fault at the level of the person who has stuffed these values on the board. If the capacitor is there just for noise protection in power lines, that’s acceptable because then it won’t matter much but if there is some difference in values of capacitors when I comes to signal lines, this is a big mistake. Kindly inform the manufacturer.

[Paleo Pete]

Kindly inform the manufacturer.

Have fun with that...Sunn Concert Bass head, common in 70's to 80's...Sunn was bought by Fender long ago and discontinued in 2002. They do have a website though.

SUNN® Support

I played guitar through one of those many moons ago, great bass amp, decent for guitar but I'd prefer a guitar amp...

[Leo_Gnardo]

Sunn was bought by Fender long ago and discontinued in 2002.

Thanx Pete, I was wondering what happened to Sunn. I s'pose Fender could rev up the brand name again while they're flopping around trying everything to make a buck.

[nsubulysses]

It's funny how they "reissued" the Model T even though it is nothing like a real Sunn Model T, and it is now becoming a totally expensive and sought after amp. I bought one used like 10 years ago for $600 and now they commonly sell for $1000-2000. I would think if Fender re-released them again they would have a large buyers market.

[Leo_Gnardo]

It's funny how they "reissued" the Model T even though it is nothing like a real Sunn Model T, and it is now becoming a totally expensive and sought after amp. I bought one used like 10 years ago for $600 and now they commonly sell for $1000-2000. I would think if Fender re-released them again they would have a large buyers market.

If I'm not mistook, Fender relabeled the Sunn Model T as a Bassman 300. I worked on a couple, both Sunn & Fender, around 2006-10, nothing like the original as you say, big complex amp. Like an SVT, sounds great when working correctly. One main problem was filament connectors burning where the transformer lead plugs into the circus board. The push on connector couldn't handle the current surge at switch-on. I just soldered the wire straight to the board.

Now back to the thread, apologies for off the road driving.

[nsubulysses]

That's the bass amp version. Still off-roading. The "Sunn" version is the 300T. Same as the Fender Bassman 300, not a Sunn design.

The Model T is a guitar amp that is 120W with 4 6L6s. It is a modern high gain amp with clean and overdrive channel, effects loop and the whole deal


Here's the 300T, essentially a Fender designed 300W "Model T" or whateve ryou would call it. These Fender made Sunn amps were produced from 1995-1999 if I'm not mistaken


And I'm just throwing this out there, and have not confirmed it, but I beleve the Fender SUnn Model T is actually just a Fender Evil Twin with a bigger output section capable of 120W

[Paleo Pete]

Leo - I didn't know it either, I just knew I hadn't seen any Sunn amps in a while and wondered so I did a little digging. I played a time or two through a Coliseum and a Concert in the 70's, have a friend in Memphis who still has an original Sunn he uses, Concert I think but I could be wrong. Normally he'll plug into either of a couple of Mesas, a Subway Rocket or a whatever rectifier head and a 4x12. But every now and then he'll pull out the old Sunn just for kicks...says it still sounds great but I didn't hear it when I went up there for a visit.