Calling all Fender Twin enthusiasts -- need amp repair help!

[jndietz]

Hi guys ... today I made a random stop at the pawn shop on the way home, and saw a lonely Fender Twin sitting in a pile of stuff. I asked if it was for sale, and long story short, I walked home with it for $200.

I am the second owner, apparently, as the shop owner knew the guy who owned it previously. The guy at the shop plugged it in and it played okay, but was only hooked up to one speaker. Two of the original Fender power tubes were laying in the bottom of the amp, I plugged 'em in and they worked just fine. I'm guessing he pulled them to reduce the headroom ? When I got home, I wired up the second speaker and it sounds great, but I guess I want to make sure I wired it correctly (to not cause too much of a load on the amp, right?). Can you guys explain how the speakers should be wired? It has the original speakers.

Also, the reverb doesn't work. It was working in the shop when he tested it out, but when I got home, it didn't work anymore. Also, does the vibrato require that a footswitch be plugged in for it to work (I read that somewhere, not sure if its true)?.

Finally, I would like some other reccomendations on what should be replaced or cleaned before I start using this as a mainstay amp. It is sure beat up, and would like to restore it as best as possible. Below, I attached some pictures. Maybe you guys can help me identify what year it was and what type of speakers they are. I might end up sending it off to a tech anyways to let him throw in some brand new tubes and replace/clean whatever else.

https://i276.photobucket.com/albums/kk3/jndietz/Fender Twin/0324092032.jpg
https://i276.photobucket.com/albums/kk3/jndietz/Fender Twin/0324092033.jpg
https://i276.photobucket.com/albums/kk3/jndietz/Fender Twin/0324092034.jpg

 

[stevieb]

YOu can find schematics easily on line, that will include speaker wiring.

Both reverb and tremolo probably require either a pedal or a RCA plug, with the two connectors, to be plugged into the RCA jacks on the back.

And if I had not paid even less for a Twin Reverb a couple years ago, I would HATE you. Good score.

 

[GOYA]

Speakers should be wired parallel.

I looks like you've got a 100w, tailless, master volume, 73-77 Twin. You might be able to pin it down using codes on speakers, transformer or pots.

Here's a good list from Tonequest:

Here are some basic checks that should be performed on any amp when it’s on the bench to be "tuned up":

1. Replace filter caps as needed.

2. Check values of voltage dropping resistors and change any that are off more than 10%.

3) Re-tension all tube sockets

4) Check and replace tubes as needed.

5) Set bias current on power tubes.

6) Clean all pots, jacks and switches.

7) Check all coupling caps for leaking DC (especially in tweed and brown and/white Fenders and any other '50's amps). Replace as necessary.

8) Replace all pre-amp electrolytic caps (on the cathodes).

9) Replace bias electrolytic cap.

10) Check values of screen and grid resistors on the power tubes and replace any that are off in value.

11) Replace junky components like chocolate drop coupling caps in Fender amps.

12) Inspect for cracked solder joints and repair if needed (several key spots are always suspect, and I’ve learned which ones they are).

13) Inspect all grounds for evidence of problems, re-solder as necessary

14) Check all key voltage points in the amp.

15) Inspect speaker cone for evidence of cracking or rubbing coil. Clean out any dirt accumulated around surround (otherwise it acts as sandpaper to destroy the outer edges of the cone).

16) Check the polarity of the speakers. You'd be surprised how many speakers are wired out of phase in multiple speaker amps (when the original speakers have been changed).

If you're not sure what to do or how to do it, spend time learning before you try anything. And if you don't know how an unplugged amp can kill you, don't even remove the chassis.

 

[GOYA]

BTW, the two tubes were pulled to lower the power of the amp and and one speaker disconnected to match the new impedance caused by pulling those tubes.

 

[jndietz]

So, I should probably just take it to a tech, eh? I don't have a big knowledge on electronics. I can change and bias tubes, thats about it. I wonder if learning and working on the amp would be more cost effective than repairing it, plus I'll learn something from it, too.

Also, whats a good OD pedal that will sounod good with this? I put my Boss DS1 in front of it and it sounded kind of trashy.