I took my reverb unit to an amp tech yesterday. The unit won't power up. Turns out, it's the transformer. The guy told me that the Fender transformers now have small fuses inside them, but that the fuses aren't needed. He unsoldered the copper that wraps around the transformer. Then, he cut and pealed back a few layers of the transformer. Sure enough, there was a tiny clear plastic fuse with an extremely slender wire inside that had broken.

The amp tech told me that he'll just by-pass the fuse with a small wire. Of course, none of this helps with what blew the fuse in the first place. I guess we'll see, once he by-passes the fuse.

So, my questions are whether or not anybody else was aware of the fact that transformers have those small fuses inside? I'm interested in knowing more about that. Apparently, the company that makes the transformers makes them with and without the fuses, but Fender uses the ones with fuses because of code. I'm also wondering if it's true that bypassing the fuse inside the transformer won't hurt anything? The amp tech told me that the main fuse is all that's really required.

Seems like a weird thing, to have a fuse inside the transformer like that!

eddiekatcher
OSHA dude............the goverment is the REAL reason we can't have amps "built the way they used to be built." It's back to that tort reform crap. The same reason all my old favorite dirt bike riding areas are drying up......... I sneak onto someone's property and ride my dirt bike.....I fall down, bust my ass and sue the dude who didn't even know I was riding there (and sure didn't have his permission written or verbal) I win...........! He was "negligent." He is "liable" for my busting my ass? Now how fuc.... stupid is that?

I'm damn surprised we can even have tube amps at all............CAUTION-HIGH PLATE VOLTAGE!

Ok, I'll get down off my soap box.....................

ksdlkdflksdjflsdhjksdhf pisses me off for sure.

ed

California is even lucky enough to have our own CALOSHA organization regulations to follow. Pretty soon we'll all be sitting around in a protective bubble, so we wont be able to harm our selves or others.

Lots of people know about the thermal fuses. I've seen a few vintage transformers that fried because of a partial short. The short wasn't large enough to cause the main fuse to blow, but it was big enough to make the transformer overheat. When I open up these transformers, I see a whole bunch of black, carbonized paper. A thermal fuse would have kept these transformers from frying.

Removing it will make the amp work again, but it doesn't solve the problem of what made the transformer overheat in the first place. I've heard of amp techs doing this but I would be very hesitant to intentionally disable a safety feature. It is possible to buy a new thermal fuse and install it in the transformer. I know Radio Shack used to sell them but I doubt they still do.

If it ain't broke, fix it until it is.

LHR
eddiekatcher: OSHA? Huh? But you are onto something. In the EU, tube amp sales were right on the brink a few years back. Reason being, they were not CE compliant, I guess. That is, they had too many "user serviceable parts", no protective cage blocking off the tube socket area from curious fingers, etc.

The only casualty so far as I know was the lead solder. Maybe some incredibly safe EU resident can enlighten us as to the final state of affairs over there (and, of course, what standards we can eventually expect imposed in North America.)

First time I hear of this issue. As far as I know the only would-be threat to tube amps were transistors. And we all know how that turned out .
Maybe this was on paper somewhere, but it didn't make its way into wider spread reality.

EDIT: I'm from Europe and have been playing for more than 25 yrs, just for clarification.

Just thought I'd let you know what happened. When I dropped the reverb unit off, I told the amp guy to go ahead and bypass the thermal fuse, but that if the transformer was bad, then I wanted to replace it with an authorized Fender transformer. I told him that it was very important to me for the reverb unit to remain stock. I specifically told him this, because, in the past, he had hot rodded my Dual Showman when I had taken in just to have the tubes biased. When this happened, I took it somewhere else to have the Showman un-modified, but I thought that I'd give this guy another chance, because he's local.

He had the reverb unit for two weeks and when I went to pick the reverb unit up, to my dismay, the guy had modified it! I couldn't believe it.

He told me that half of the transformer was bad, but that half of it was OK. The bad half had caused the thermal fuse to blow. So, what the moron did was to go ahead and bypass the thermal fuse and leave the transformer in, but to disconnect three of the wires that were from the "bad side of the transformer" as he put it. Then, he put in a smaller transformer to drive the tube filaments, which is what he told me had been the job of the part of the original transformer that he had disconnected.

He swore that everything was still stock, but it bothered me that he had done this without asking, especially after my insisting that he don't mess with anything. He told me that he had called Fender and had been told that there was a long waiting period for that model of transformer. I'm not sure whether or not I believe that he really called Fender, but I told him that I can buy an authorized Fender transformer on eBay for $39. He replied that he would never trust a transformer that was bought online and that he wouldn't install it.

At that point, it was worth the $40 service charge just to get it away from him. I took it home and plugged it in and -- no surprise here -- the reverb unit sounded like crap. It had become harsh and shrill. I immediately went to eBay and ordered the $39 transformer. It arrived last Thursday and I took out the old transformer and the new smaller transformer that this guy had installed. In doing so, I realized that he had run three of the wires from the smaller transformer to places in the circuit where no line from the transformer goes, according to the schematics.

Once I undid his horrible job, it only took minutes to install the new transformer. I plugged it in and it sounds great. In fact, I played a three hour gig at a car show yesterday and had no problems at all.

I guess the bottom line isn't whether or not the thermal fuse should be bi-passed, but that amp techs who don't communicate with their customers aren't worth their salt. Also, this shows how amp techs who might be familiar with amplifiers still might be in unfamiliar territory when it comes to reverb units!!!