| Author |
Topic: Q: Wha' happened???? A: Internal Fuse |
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 2 Jul 2008 1:12 pm |
|
I was just playing through my 65ri twin, stopped to answer the phone, and when I hung up on the telemarketer (who else?), my amp was dead as a doornail. No juice. No funny smell (as in a fried transformer). No blown fuse. No nuttin'. No electrical storms in the area (anyway, my RV3 that is plugged into the same power strip is still on and happy).
I'll take her in to the amp doctor tomorrow, but does anyone have any guesses as to what happened. Evil-wizard telemarketer?? Twin didn't like my playing and couldn't take it anymore??
Dan
Last edited by Dan Beller-McKenna on 8 Jul 2008 11:36 am; edited 1 time in total |
|
|
 |
Donny Hinson
From:
Glen Burnie, Md. U.S.A.
|
Posted 2 Jul 2008 3:59 pm
|
|
| Make sure you got juice at the outlet. If you do, then the problem is in the power cord, fuse, switch, or power supply. If the amp has an accessory outlet in the back, see if there's any power there, too! |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 2 Jul 2008 4:10 pm
|
|
Tried several different outlets; no go. Fuse looks fine. I would have expected something like the power supply to give some other symptom than just disappearing, but I'll bet it's that. Hopefully the tech will tell me otherwise.
*Sigh*
Good thing I bought a silverface twin a couple of months back!
Dan |
|
|
|
Steve Hamill
From:
California, USA
|
Posted 2 Jul 2008 4:29 pm rectifier
|
|
| had the same thing happen to me once and it turned out the rectifier tube had gave up the ghost. Replaced it and all was right again. Might try a different one if you have it. |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 2 Jul 2008 4:37 pm
|
|
| I don't think this twin has a rectifier tube. SS rectifier. |
|
|
|
Mark MacKenzie
From:
Franklin, Tennessee, USA
|
Posted 3 Jul 2008 4:29 am
|
|
| Did you look at the speaker connection? |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 3 Jul 2008 4:39 am
|
|
Not the speakers. We're talkin no electricity period. The light is out. Nothing alive in there at all. "You could hear a teardrop fall."
Dan |
|
|
|
Jim Palenscar
From:
Oceanside, Calif, USA
|
Posted 3 Jul 2008 5:36 am
|
|
| At the risk of sounding lame- you might consider checking the fuse with an ohm meter regardless of what it looks like- just to be sure and keep the egg off your face when taking it to the tech (I've had to wipe it off mine on numerous occasions). I know it's a long shot but they don't always fail where you can see them. |
|
|
|
Bill Creller
From:
Saginaw, Michigan, USA (deceased)
|
Posted 4 Jul 2008 7:22 am
|
|
| A few items could cause a failure, like even the power toggle switch. If you have a VOM you can check incoming power to the switch, and after the switch. If no tubes are lit, the PT may not be getting line voltage. Hopefully the PT is OK. |
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 4 Jul 2008 7:36 am
|
|
Does the TRRI have a courtesy outlet? As per Donny's post, if you have juice flowing there then that gives at least a little info. And if it does have juice, then you could plug your amp into it!
I like the idea of rechecking the fuse. Without even a glowing pilot light, it would seem that there's a fundamental power problem. Schemos for the original TR shows power comes into ground switch, courtesy outlet, fuse, light, on/off switch, all before going anywhere else.
And no, Twin Reverbs don't have tube rectifiers. If yours did, then I'd say "there's your problem."
----edit---the light not being lit would not be an indicator of much. It could just be burned out. This would not (should not) affect the power downstream). |
|
|
|
Greg Simmons
From:
where the buffalo (used to) roam AND the Mojave
|
Posted 4 Jul 2008 8:53 am
|
|
FWIW, I had similar behavior (though intermittent) with my silverface Deluxe Reverb a few years ago; as mentioned above by Donny & Bill, it was the power "on/off" toggle switch.
_________________
<i>�Head full of this kaleidoscope of brain-freight, Heart full of something simple and slow�</i>
-Mark Heard
|
|
|
|
Jim Sliff
From:
Lawndale California, USA
|
Posted 4 Jul 2008 10:12 am
|
|
As someone already noted, TEST the fuse - "looks fine" is meaningless.
With no smell, I doubt it blew a transformer or cap.
A couple of other things to check:
1. These amps have a removable power cord to meet export codes. Are you SURE it's plugged in all the way? If so - next try another cord (the one from your computer should fit if you don't have a spare.
2. If you still get nothing, turn on just the power switch (standby should be off (and look at the tubes. Do you see a filament glow inside them? If so, that's a good sign - it means at least power is getting to the power transformer AND part of the power transformer is working.
If there's no glow you're not getting power as the 6.3V filament tap isn't lighting up. It could be a switch or something before the power transformer...if so, you're very lucky and it should be an easy fix. If the PT is bad - ouch.
And yes, no one could have had the same problem and fixed it with a new rectifier tube - there IS no rectifier tube. Twin Reverbs have always used a solid-state (diode) rectifier, but if the tube filaments are dead the rectifier would not be the problem (it's not part of that circuit)
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 4 Jul 2008 11:08 am
|
|
Hi folks,
thanks for all of the ideas and sugegstions. The amp's at the shop now with a trustworthy tech. He did check the fuse on a meter before taking the amp in: fuse is fine.
To reiterate: there was no electricity operating in the amp at all: no pilot light, no tube filaments glowing, no souind faint or otherwise--dead as a cold slab of New Hampshire granite. I did not know about the detachable power cord(!): should have checked that! I'm crossing all my digits hoping it was something as benign as that or a bad toggle switch. However, seeing as I inherited this amp, I can't really feel too miserable if I do have to shell out a couple hundred buck to bring it back to life.
Dan |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 8 Jul 2008 11:24 am
|
|
Internal fuse blew.
Apparently there is a 10 amp internal fuse for the transformer filaments (???: I'm trying to repeat what the tech said, but am probably making up all sorts of electro-impossibilities as I go). The holder for the fuse had come loose, causing it to overheat when it came in contact with something on the board, thus eventually blowing the fuse.
The tech guessed that this was likely caused by a bad solder point or just flexing of of the very thin pc board. (Why would it flex?) I suppose this could be a downside of the pc-board, modern reissue twin construction as opposed to an older, handwired, sturdier construction. On the other hand, the entire repair took about an hour and cost $52, so I'm not sure, at least in this case, concerns about the difficulty of repairing a re-issue vs. an older tube amp are borne out.
Also, to clarify: the power cord on this twin ('65 ri) is not detachable, and no, it does not have an auxilliary courtesy outlet.
BTW: the tech had a hard time finding a 10 amp fuse. He finally located one at a nearby marina(!) I told him that seemed appropriate since twins WEIGH AS MUCH AS A BOAT ANCHOR!!! 
Have my new Weber speakers arriving tomorrow; can't wait to try them out in this and my SF twin.
Dan |
|
|
|
Ken Fox
From:
Nashville GA USA
|
Posted 8 Jul 2008 12:22 pm
|
|
You must have a rare amp there. No internal fuse is shown on the 65 Twin Reissue amp's schematics.
Maybe it was an add on. Marshall likes to do that in their amp. Helps a lot when a power tubes goes south and shorts out its other elements to the heater elements. |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 8 Jul 2008 1:25 pm
|
|
May be "rare"; I was just glad the tansformer wasn't "well done." 
It's all foreign to me. Ken, do you mean that Fender might have added this fuse to the circuit later in the amps production? I'm curious because I don't know what year the amp is. The double letter code that should be on the service assurance tag is a "W" (??? uoside down "AA"???)
Dan |
|
|
|
Ken Fox
From:
Nashville GA USA
|
Posted 8 Jul 2008 2:17 pm
|
|
I am not sure. May have been added by a tech as an after thought! I doubt it was original equipment.
Still, a nice feature to have. |
|
|
|
Jerry H. Moore
From:
Newnan, GA, USA
|
Posted 8 Jul 2008 5:23 pm
|
|
My 65 ri blew the same fuse!!! I was working on this guys Hot Rod and was trying to sell him the 65 and he blew it on stage!. For Ken, some of the schematics don't show it. I found it on the Fender CD of schematics. Bastard fuse to find too. The guy had similar problems with his Hot Rod Deluxe. I advised him to upgrade his power supply and maybe split some of it up, He has a ton of pedals! I have played the Twin since and had no problems and the Hod Rod is doing well too. SO....Dan, you may check all your power sources.
I'm not a repairman ..only a novice. The names were changed to protect the innocent. No animals were harmed... |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 8 Jul 2008 5:36 pm
|
|
Jerry,
the strange thing is, the RV-3 was plugged into the same power strip and didn't flinch. But here is one weird phenomenon. The telephone in my study/music room has had a loud (annoying!) humm for years. Since that phone call when the twin died, the hum is gone....
do-do-do-do, do-do-do-do, do-do-do-do .... (sung to the tune of the twilight zone theme)
Rod Serling: "A phone call from a seemingly innocuous telemarketer, an amplifier that suddenly dies, and a fuse that shouldn't exist: either you're living in twent-first century America, or you've entered .... the Twinlight Zone!!"
Dan |
|
|
|
