For Waisznor and Mike Brown

rmason · From: Caracas, Venezuela

I operated my amps from country to country
from 110v to 220v (with a voltage transformer) and back to 110v again over
many years in the Foreign Service and never
had a problem. Mike is right of course,
about the transformer's capacity; a small
500 watt xfmr will do for most any amp.

Here in Caracas, most every dwelling is
now wired for 110v. I visited a German
friend last New Year's eve and plugged my
amp directly into his wall. Turned out he
had had the apartment voltage rewired to
supply 220v to all his European appliances.
It was an acoustic party after that.
Fortunately, when I got home and opened it
up, it was just a blown fuse. No other
damage that I could see or hear.

And speaking of fuses: Mike, I've got two
amps, a Peavey and a Crate, both with the
fuses deep inside the cabinet on the chassis.
What's with modern amp mfrs? There's plenty
of room on that front panel for a fuse
holder. Otherwise, love my Peavey, but it
won't be perfect 'til those fuses are
reasonably accessible. I'm thinking of doing
it myself.

------------------
Rod Mason

Earnest Bovine · From: Los Angeles CA USA

I am surprised that your plug would fit a 220 volt outlet. Different plugs make the different voltages idiot-proof. (I am not calling you an idiot!)
Japanese plugs are like USA plugs, but 100 volts and 120 volts are near enough as makes no difference.

rmason · From: Caracas, Venezuela

True, Ernest, but in this case the wall
receptacles were left as they were when
the apt. was built, our standard U.S.
110v types; typical workmanship here in
Caracas. I didn't know it until after I
blew my fuse but my host was using the opposite kind
of plug adapters for his stuff with a
blade-type male end and little round holes
on the other. I think these may have
developed in Paris. When I was there in
mid-60's I was told 110v and 220v was
sprinkled all over the city and could vary
from block to block.

------------------
Rod Mason

Mike Brown · From: Meridian, Mississippi USA

There are several reasons of why some fuses cannot be accessed externally on some Peavey amps. Certain amps can have multiple internal fuses for several reasons. For instance, a tube amp has a filiment fuse to prevent major damage to rest of an amplifiers circuit should a tube become intermittent. Certain sections of an amp are fused to avoid major repair costs and save the consumer additional expenses. It may seem that this method of protection costs the consumer "up front", and it does, but the cost is not near as expensive compared what the repair costs could be should the amp fail.

Now, the idea is to build an amp that doesn't fail, right? Well, since tubes are an expendable part and have to be changed periodically, they "can" become intermittent. And the word is that the quality of tubes are not what they used to be.

Normally, when fuses blow, its not going to be just the fuse. Also, fuses deep inside the amp are there to fuse the low voltage preamp section or other critical areas which lessen the damage done.

Safety is another point that has to be considered when designing amplifiers. In the past we have included a circuit breaker switch on our PV series of power amps, but unfortunately these had to be removed as users would continually reset the amp when the amp had a problem internally. However, the circuit breaker ensured the safety of the amp if the building voltage was sufficient.

The bottom line is that if an internal fuse blows in our amps, there is a problem internally that needs to be repaired by a qualified technician.

Bob Metzger · From: Waltham (Boston), MA, USA

Mike, excellent answer. I've 'gone over' to the other side of this issue. I believe all fuses on all amps should be internal. Almost never is the fuse the only part that fails. It's almost always an indication of something pulling way too much current (something failing or about to fail) and fuses save us all from vastly bigger and more catastrophic repairs (and bills). Amplifiers today are generally much safer and protected (fused) more extensively than ever before.

I currently advise amp users as follows: If an amp blows a fuse, power down the device, pull the fuse, replace it with a fuse of the correct value (it almost always says the fuse value on the unit), if it has a 'standby switch' use it, if it's a tube device, examine the tubes while on 'standby' (and shut it down if observing anything out of the ordinary) - before moving on to 'play' position, and then, re-power up. If it blows a fuse again, it's time to take it to a qualified tech. I've only had one instance in many, many years of being around amps that the 2nd fuse corrected the situation and the amp worked fine after that. Apparently, the fuse itself became fatigued and failed physically (not electrically) as it had been in that particular amp for twenty years plus. If a manufacturer puts the fuse(s) internally, a decision is being made that the probability of a parts failure and the unit needing expert attention is great. Although, it is 'traditional' for tube amps to have external fuses, and solid state amps to have internal fuses, many manufacturers (tube guys as well) fuse multiple functions internally, as well (as Mike said). It's not really a user serviceable function anymore.

Bob

Jack Stoner · From: Kansas City, MO

Mike Brown has some excellent points for non-user accessable fuses. I've repaired stuff that could have been avoided (or minimized) if the user had installed the proper size fuse. However, equipment cannot be totally "idiot proofed". Even with internal fuses people will still get into them and screw things up - sometimes worse than if the fuse had been accessable from the outside. But, putting the primary fuse internally penalizes the majority because of a minority that screw things up.

I'm not drumming up business as I no longer do amp repair other than my own and for a few friends.

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