[PVRCNC] Dead power supply question

Keith Zeringue kazeringue at aol.com
Mon Jan 14 09:00:21 EST 2008


Okay, I thought I'd give you jokers first crack at this question.  Odds 
are 95% of you are better qualified to guess at it than I am.

Set up:
The dead power supply is the Yaesu FP-1023, a switcher rated for 22A, 
25A surge.  NO schematic available, dang their evil hearts.

Besides the blown fuse, the only part on this power supply that is 
showing obvious signs of physical damage is a small axial capacitor 
across the output.  It failed dramatically as a "carbon cinder", making 
a dead short across the 12v, 20A output.  My first guess is that is was 
originally an axial dipped ceramic cap, but the corpse was pretty much 
toasted.

Question:
Any guesses as to the purpose such a cap might be performing?  Seems to 
me it must be an RF bypass.  If so, any educated guesses as to a 
replacement value?  .01mf sound about right?

Anybody else out there OWN an FP1023, and can read a value off the cap 
(C24)?

Hopefully Rat Shack will still have a box of fuses.  Danged if its not a 
6.3 amp fuse.  (Like I've got a box of those laying around.)

If I can locate a fuse, I'll cut and scrub the remains of the carbon 
cinder away and see if it fires up without the dead short.  If the fuse 
goes ka-blewie without the short, the corpse is off to somebody's junk 
box, and I have a nice small project box.

Any pertinent speculation and WAG appreciated.  Impertinent speculation 
appreciated only if humorous. :)

73,
W4KAZ


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