[R-390] Blown B+ Fuse - Cont'd

[Barry Hauser]

Lee wrote:

> Fuses wear out and blow for that reason besides protecting a circuit.
> Surges and vibration also take their toll on a fuse besides just the every
> day daily current flow throught the fuse.


Barry mentioned that he had just put in the correct fuse (1/8 instead of 1/4 
amp), though slow blow rather than the F/B that's supposed to be used.

In addition to wear and tear, defective fuses aren't unheard of.  If NOS --  
really old -- there could be some deterioration on the shelf, depending on 
storage conditions.  Fuses aren't sealed.  I've seen some where the glue had 
given out and just installing them causes one or both end caps to twist --  
also some that looked corroded inside or had an awful lot of rosin showing 
in the end-caps where the wires are soldered.  I suspect a bit of corrosion 
or a slight twist can affect the actual current "tolerance".  And there can 
be some that were just made wrong/defective.  I'd check another one with 
just one of the meters in series, since they read the same when the current 
was measured before.  May as well put in another order for 1/8th amp 
fuses -- fast blows -- from another source.

Barry