| Author |
Topic: Help with Fender Twin Reverb Reissue Amp |
Joshua Tschetter
From:
South Dakota
|
Posted 29 Dec 2023 7:13 am |
|
Hi, and thanks in advance…
After a recent move my amp started to act up, it fades in and out of consciousness. The power tubes stay on but I am having trouble on the pre-amp side. I have to hit it on top of the head for the tubes to come on, then after a minute or 2 they fade off again till I hit it again. Sometimes it will stay on for longer periods, like 20 minutes or so…this must be some kind of loose connection, but what exactly should I be looking for?
Thanks, JT |
|
|
 |
James Holland
From:
Alabama, USA
|
Posted 29 Dec 2023 7:57 am
|
|
| One possible issue, the tube sockets need "re-tensioning", where the pin sockets are squeezed back into shape, to provide enough clamping to the pin...it takes a while to re-tension each pin socket. |
|
|
|
Robert Parent
From:
Gillette, WY
|
Posted 29 Dec 2023 8:15 am
|
|
| I would check for a cold solder joint. |
|
|
|
Tim Whitlock
From:
Colorado, USA
|
Posted 29 Dec 2023 10:55 am
|
|
| James Holland wrote: |
| One possible issue, the tube sockets need "re-tensioning", where the pin sockets are squeezed back into shape, to provide enough clamping to the pin...it takes a while to re-tension each pin socket. |
This seems a likely possible cause that you can try to fix before you shell out $ to a tech. Check each tube to see if any of them feel loose in the socket. If they do you can use a small screwdriver to push the tiny clamps that hold the pins back together. Of course make sure the amp is off and your screwdriver has an insulated handle. While you are at it it's good policy to clean your tube sockets with electrical cleaner. Just spray a little cleaner in the sockets and on the tube pins before you re-insert the tube. |
|
|
|
Raybob Bowman
From:
S. Lake Tahoe, CA, USA
|
Posted 29 Dec 2023 11:05 am
|
|
Clean tube sockets with Deoxit.
_________________
Sierra U12 4+5 / 1933 Dobro / homemade Tele B-bender |
|
|
|
Donny Hinson
From:
Glen Burnie, Md. U.S.A.
|
Posted 29 Dec 2023 3:04 pm
|
|
Try wiggling the tubes when it cuts out.  |
|
|
|
Bill A. Moore
From:
Silver City, New Mexico, USA
|
Posted 29 Dec 2023 3:27 pm
|
|
| You guys have it all wrong, I've watched guitar players for years beat on the top with their fist! Seems it either quits altogether, or it starts working until the next gig! |
|
|
|
Mark Peters
From:
California, USA
|
Posted 29 Dec 2023 3:51 pm
|
|
| What Bill said -- percussive therapy. |
|
|
|
Joshua Tschetter
From:
South Dakota
|
Posted 29 Dec 2023 4:32 pm
|
|
| Thanks for your advice gentlemen, I’ll check it out. |
|
|
|
Joshua Tschetter
From:
South Dakota
|
Posted 29 Dec 2023 4:33 pm
|
|
| Bill A. Moore wrote: |
| You guys have it all wrong, I've watched guitar players for years beat on the top with their fist! Seems it either quits altogether, or it starts working until the next gig! |
Bill I imagine this to be true 😂 |
|
|
|
Dave Grafe
From:
Hudson River Valley NY
|
Posted 30 Dec 2023 1:08 am
|
|
Before you poke around in there be sure to drain the power supply caps by leaving it unplugged and turned off but with the standby switch turned on. The bias resistors will allow stored voltage to dissipate in a few munutes. No use in joining the 500 volts surprise club. Check power tube plates with a meter to be certain there is no voltage remaining before proceeding.
The RI blackface amps use the same AB763 circuit as the originals but the power transformer connections are no longer soldered, instead they use push-on clips to make manufacturing less expensive. These have been known to slip and cause trouble and it sounds like these are what is giving you fits. The easy fix is to clean and re-crimp them all, the real fix is to remove the clips altogether and solder the connections permanently, as was done in the originals.
Good luck, that's a fine amp when working properly. |
|
|
|
Joshua Tschetter
From:
South Dakota
|
Posted 30 Dec 2023 9:31 am
|
|
| Dave Grafe wrote: |
Before you poke around in there be sure to drain the power supply caps by leaving it unplugged and turned off but with the standby switch turned on. The bias resistors will allow stored voltage to dissipate in a few munutes. No use in joining the 500 volts surprise club. Check power tube plates with a meter to be certain there is no voltage remaining before proceeding.
The RI blackface amps use the same AB763 circuit as the originals but the power transformer connections are no longer soldered, instead they use push-on clips to make manufacturing less expensive. These have been known to slip and cause trouble and it sounds like these are what is giving you fits. The easy fix is to clean and re-crimp them all, the real fix is to remove the clips altogether and solder the connections permanently, as was done in the originals.
Good luck, that's a fine amp when working properly. |
Thanks for this info Dave, In that case I will solder them on.
Best Regards, JT |
|
|
|
Ken Metcalf
From:
San Antonio Texas USA
|
Posted 31 Dec 2023 7:06 am
|
|
Have you tried the old thump the tubes test with your finger?
_________________
MSA 12 String E9th/B6th Universal.
Little Walter PF-89.
Bunch of stomp boxes |
|
|
|
Joshua Tschetter
From:
South Dakota
|
Posted 31 Dec 2023 8:19 am
|
|
Hi Gentlemen,
I took all ya’all’s advice, cleaning tube sockets, some soldering, and electrical contact spray, and I am happy to report I haven’t had to “knockelhead” the amp for a few days! Thanks so much for all your time and advice. This bunch is the best!
Best regards, JT |
|
|
|
Dave Grafe
From:
Hudson River Valley NY
|
Posted 31 Dec 2023 1:40 pm
|
|
| Success is good 😎 |
|
|
|
