Blowing fuses

[fifty9 335]

Hi, I have a Bruno super 100 that keeps blowing the 1 amp fuse. It has both a 5A and 1A fuse. Is this fuse directly related to the power tubes? I have no way of testing the tubes and am wondering if they might be bad. Or might it be something worse?

Thanks All :confused:

[scottl]

Why don't you email Andy Fuchs. He has a Super 100 in his shop. He is fixing it for someone. I know he is familiar with that amp.

Scott

[John Phillips]

That sounds most likely to be a tube problem - if that's the HT (B+) fuse, which it should be if it's the lower of the two values. The high voltages to the tubes are supplied through this fuse, and if one goes bad it will usually blow the fuse.

Are you using the right type of fuse? - if it calls for a Slo-Blo, Anti-Surge or 'T' type fuse, a normal fast-blow will blow fairly regularly.

Does the fuse blow pretty much immediately or only after a while?

Does it blow if the amp is turned on with no tubes in? If so, it's something more serious. If not, it's almost certain to be a tube.


If you gave a good supply of fuses, you can easily test the tubes - run the amp with only two, since I assume that's a 4-tube amp - inner pair or outer pair. If it stops blowing them, the bad tube is in the other pair.

If it doesn't stop blowing them, swap to the other pair. If it still doesn't stop, you've got a more serious problem, probably - it's unlikely that more than one tube has gone.

If it is a tube, you can find out which one by picking one tube from the 'good' pair and one from the 'bad' pair (label them with a marker or something) and trying them.

[fifty9 335]

Thanks John i'll try that. I appreciate your help.
Thank you too Scott. If its more serious i'll call Andy.