Workbench device question

[mrnisseguy]

Some years ago I had taken one of my big tube amps to a friend who worked as a tech in a stereo store for years.

It's been over 5 years ago but I seem to remember he had some device or equipment that allowed him to test the amp circuit without having the fuse installed, or it was bypassed in some way........if I am remembering correctly, does anyone know what that was called?

 

[VaNarn]

Several methods are used for initial testing of equipment to guard against shorted circuit problems .'Variac' adjustable transformers. Isolating transformer(with inbuilt overload protection and if using a really old type;one with a satureable core.A series fitted light globe,that will indicate excessive current draw.

 

[rayma]

he had some device or equipment that allowed him to test the amp circuit without having the fuse installed, or it was bypassed in some way.

If he removed the fuses, then he likely connected an external dual power supply. These usually have current limiting, so they would be safe to use.

 

[Enzo]

Big darn power supply for a large tube amp. I'd say he needs at least a triple supply for that. B+, C-, and heaters.

I really suspect he was just describing a very common "light bulb limiter", which you can google and see a zillion little articles about. Very simple to make. it doesn't bypass the fuse, but with it, a shorted amp won't BLOW its fuses. If the amp wants to draw a ton of current, instead of blowing the fuse, it simply causes the light bulb to glow brightly.

 

[audiomik]

Using a Light Bulb in series with your mains supply to the Amplifier or other device to be tested is a good way to limit current from your mains supply. Plenty of information on this on the internet. hope this assists Mik