Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

 
 
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N Cook
 
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Default 300W PC power supply, no POST beep, smell, smoke, bang,dead

Jou Jye 300AP
Blown 5 amp mains fuse
There is a 1/2W resistor between the common point of the 2 x 200V mains side
electrolytics
and one of the 2 leads , high V side of the large isolation transformer,
marked on pcb as R5 now reading 98 ohms
Overheated and probably had a brown and a red band somewhere in the value.
Covered with some 125 degree shrink-sleeve that has charred. This was to
protect against touching other parts but this R was on end and lead doubled
back and presumably the bang was the long lead shorted to the other barrel
end of the R as severe tell-tale smoke 'jet-trails' at that point, no
ceramic spacer or anything .

Anyone hazard a guess what the original value might be. ?
The 2 main 2SC2625 and 200V electrolytics seem OK.

Parallel to the 4 wires of the mains side bridge rectifier is a small
sub-circuit
with (2S?) K2645 and a L8561 8 pin IC, is this all a crow-bar circuit to
knock out the mains fuse?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




 
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