Fortron 400W Burnt Out

[Chris]

Well guys i'm after a little advice I bought a Fortron/Sparkle 400W PSU from ebay a while ago, and used it for a coulple of week. I then opened it up and noticed some burn marks inside it, it was too late to contact the seller so I put my Antec 300W back in a put this in the cupboard until now.

I really would like to use it again as its an excellent PSU and I could do with the extra power. If you look at the picture I have attached it looks the the resisitor has caused the burn marks to the PCB yet the Resistor its self is in perfect nick, witch leads me to belive that its been repaired. Do you think its been repaired? Do you think its safe to use?

 

[larrymoencurly]

I have a TV that's been running for years with a hot resistor and a circuit board burned under it. A new resistor with a higher power rating will run cooler, but just raising the existing one off the circuit board by melting the solder on its leads and pulling it up could improve the air circulation enough to lower the temp. I've seen circuit boards with holes drilled in them for cooling resistors and other hot stuff.

 

[L337 M33P]

What part of the PCB is this resistor on?

That is a high-power resistor, and obviously it is meant to heat up a fair bit. In my other 300W PSU there is a resistor about the same size with that goo all over it (stuff they use to secure large components to the board) - the goo has gone brown. Ever wonder why a new PSU smells "new" for a couple of days? It's the resistors inside heating up and doing their thing.

Resistors and PCBs can get hot without much damage, but I would be more worried about that zener diode right next to it. I think it is there to provide a control voltage of sorts and so having a crispy resistor in the vicinity will alter the voltage across the zener.

Without more info I can't really say. Have you got a shot of the underside?

 

[Oklahoma Wolf]

I myself think it'll probably be ok to use, but in my repairs I usually desolder and resolder these resistors so they're a couple millimeters off the PCB when I see this type of moderate heat damage just as a precautionary measure.