[R-390] Blowing B+ fuse

[Tim Shoppa]

> I finally got a couple of 1/8A B+ fuses (SloBlo)

I think that the B+ fuses are supposed to be non-sloblo (fastblow).
The idea is that a short/overload on the B+ should break the circuit
immediately.

Incidentally both my R-390A's came to me with 2 or 3A fuses in the B+
positions.  May as well have been a penny...

> [Blowing fuse = bad electrolytic filters]

Probably.  Do the electrolytic cans get noticeably hot (hotter than
the chassis around them at least?)

It's entirely possible for the electrolytics to still have enough
capacitance to effectively filter but have so much leakage that
they blow the fuse.

Also check for burnt resistors on the decks... indication that
a tube is drawing way too much current.

The army manual has a good procedure for finding B+ shorts with an
ohmmeter but it doesn't always show up too-much-current-when-real-power-
applied faults.

Tim.