Solid State Fender Twin Reverb SR2100 from 1968 - Hum and Low Volume

[Gh987oo]

Solid State Fender Twin Reverb SR2100 from 1968
I am getting a very low volume and hum from this amp. I am wondering if anyone can point me in the right direction regarding where to purchase and what type of power caps I would need for this amp.  The values are 4000 MFD at 45 Volts (C 3 and C6) and 500 MFD, one at 30 Volts  and the other at 35 volts (C 5). Please see schematic. Any help would be greatly appreciated.

Rick

[sluckey]

I would look at Mouser for those caps.

[shooter]

what are the main voltages on J4?  how close are they to the schematic?

[Gh987oo]

Shooter,

I will get that info out to you when I have the amp in front of me which may take a little while. 

Thanks

Rick

[sluckey]

I suggest you put your hands on this amp before buying any caps. Those 4000µF just may be chassis mount cans.

[Gh987oo]

I am thinking that radial caps with a value of 470 UF at 50 volts and 4700 uf at 50 volts might work and the cheapest way to go and the closes in value to the original. There are 3 chasis mounted caps and one of them is hot.

[sluckey]

There are 3 chasis mounted caps and one of them is hot.

Caps should be room temperature. A hot cap is a bad cap.

[Gh987oo]

My bad. I was referring to the ground on the caps. Two of the cans are grounded to the chasis and one (the "hot" one) isn't.

[shooter]

since we have a schematic, could you reference the part, like C6...make helping lots easier

[Gh987oo]

There are two cans at 4000 UF at 45 Volts which are at position C 3 and C6 on the schematic and a two value cap can at 500 UF, (one at 30 Volts  and the other at 35 volts) which is at C 5. Please see schematic. Again thanks for any help.

[PRR]

> Solid State Fender Twin Reverb SR2100 from 1968

That is a very OLD amplifier. Nobody makes power amps like that (with driver transformer, 100W/pr) anymore, with good reason. I think there is a high chance both of the power transistors are blown. And they don't make those fat-junction types anymore. I'd hate to see you pour a pot of cap-money in there and find it wasted.

Are these really worth $400-$800???

https://www.thegearpage.net/board/index.php?threads/what-the-h-kinda-fender-twin-is-this.1409654/

[Gh987oo]

Yes I would have to agree with you PRR probably only worth some of the parts that are in it. It was just something I picked up. The power transistors were totally insufficient when designed but I will check them. There is a great series of articles about this amp. Again I am a newbie and I just wanted to see if I can bring it back to life. The power caps that I want to use to replace would only be a couple of bucks anyway but I would have to improvise hence my request above for any help or advice.
The articles are
https://gitec-forum.de/wp-content/uploads/fender_ss_twin_reverb_pt_1.pdf
https://gitec-forum.de/wp-content/uploads/fender_ss_twin_reverb_pt_2.pdf
https://gitec-forum.de/wp-content/uploads/fender_ss_twin_reverb_pt_3.pdf

Article 2 has a comprehensive review of issues regarding the circuit of this amp.

[PRR]

Go ahead and improvise.

[Platefire]

Well Anyway, seeing these SS amps is interesting. Somehow I missed these model Fender SS amps. I thought I had seen all the old vintage fenders but not these. I hope you can get it going on the cheap!

It's always amazed me the way they boldly presented the type amp "Solid State" back in the earlydays of SS. That was cutting edge technology supposedly in those days. Here 50 years latter they still trying to out-do the tubes. They getting closer but not sure they made it yet. Platefire