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Dead DECHUB 90 power supply or saveable ?

S

SunDown79

Veteran Member
Joined
Sep 8, 2005
Messages
798
Location
Netherlands
So with a group we acquired some DEC items and among them was a DECHUB 90 which I took over.
But it didn't power up, not a beep, not a boom, no smoke, nothing.
So opened the power supply up and immediately on the component/top side I could see blackness but nothing exploded or melded etc
The bottom looks even more like someone set fire to it :p
See https://stefandump.stack.storage/s/TkgpXfqesvJ2UtBI for some quick pictures.

Your thoughts ?
 
The resistors have cooked the board, but the traces don't look damaged.

C11 might be bulging slightly, and it's proximity to the scorching hot resistors is probably the cause.

I'd re-cap it and see what happens. I'd also check the resistors and see if any have opened due to heat cycling.

CW
 
I should be able to do that, even if I am not that big of a soldering guru ;)
Any idea what kind of resistors these are ? Probably some high wattage but how much ? (can't see anything indicating the watts) The ohms vary but are written on the side, all 5%.
 
They look like wire wound resistors, but I can't be certain. I wouldn't replace them unless they measure open circuit, or are physically damaged.

CW
 
So replaced the one capacitor that looked dodgy and was hoping that would be it but no-luck.
And did order all the other capacitors but thought to have a little more research and try to measure some things as it is doing absolutely nothing (not hindered by any real knowledge mind you).

So I came across this red blob X2 capacitor and I was measuring 230V before but almost nothing behind it.
Now I could be doing it wrong so first question; am I correct into thinking it should produce 230V behind it too ?
And if so, how would I best measure it ?

IMG_7049.JPG
 
X2 capacitors are typically Line to Neutral, so one side being near ground potential isn't unexpected. Usually they fail shorted and blow the associated fuse.

CW
 
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