[TenTec] Model 963 25A Power Supply 'burning smell' problem

[Jerry Volpe]

Anyone else experience over-heat damage to the the fuse area on the 
963's power supply's circuit board? If so, what did you trace the 
over-current problem too? In my case it appears that the mini-glass 
fuses are getting too hot and oozing a reside out one end which seems to 
be contaminating the physical connection of the fuse at that end and the 
circuit board clip.... thus inserting some resistance where it shouldn't 
be. This increase in resistance is creating a current 'hot spot' where 
the clip is soldered to the circuit board and that area is beginning to 
literally burn. The power supply is about two years old.

About two months ago I noticed a bad 'burning' smell in the shack for 
the first time. Took a few moments but the smell was traced to my 963 
power supply running my Orion 565. Power output voltage was correct, 
nevertheless I turned it off immediately and did a visual inspection. 
Inside I found the circuit board had a small chard area on one side of 
the circuit-board mounted fuse clip (as described above). I also noted a 
reside around that end of the glass fuse. There were no other signs of 
overheating on any other components or on any other part of the circuit 
board.

I replaced the fuse with a new 10a, 220v fuse and cleaned the fuse 
holder... checked the solder connections.... reassembled. All was good 
till this morning. Of course I was getting ready to 'chase' a new one 
and that familiar smell was in the air. Turned the power supply off and 
did another internal inspection. Found the new fuse 'leaking' on the 
same end of the fuse clips and that charred area a bit larger this time. 
I drilled the back panel and mounted an appropriately sized screw-type 
fuse holder. I removed the old clips from the board and attached #12 
stranded/insulated wires between the circuit board and the new fuse 
holder..... replaced the fuse. At the moment all is well. However, I did 
purchase an Astron RS-35M to replace the 963 until I can figure this one 
out.

Thoughts?

73,
Jerry, KG6TT

-- 
Ralph Jerald "Jerry" Volpe
Amateur Radio Operator KG6TT
FISTS 12304
http://kg6tt.tomorrowsweb.com
788 Chestnut Drive
Fairfield, CA 94533

kg6tt at arrl.net

510 325-7724
707 399-8838 FAX