PC power supply fail after power a power outage

[tedstruk]

I have a strong running Dell small factor desktop power supply that went through a power outage and now the fan doesn't run and the PC won't turn on. So I pulled it out, it's a 250w BEST and SATA in a long box... this is my first SATA repair, and as I would assume it is probably not much different, just series instead of parallel.

Are there any standard procedures I should follow before I test it with my o-scope,?

Where would be a good place to start checking for problems?

 

[tedstruk]

Is there a switch point that turns it on? never mind... I will just probe araound and see shat I can find!!!

 

[tedstruk]

sitchyayshun....

The fan stutters on power on, trys to start, no power on, and all the signals are low, 3 red wires read 2 volts, the rest are way down .8 and lower. Whats my problem???

 

[davenn]

The fan stutters on power on, trys to start, no power on, and all the signals are low, 3 red wires read 2 volts, the rest are way down .8 and lower. Whats my problem???

have you tested all the output rails 12V, -12V, 5V 3.3V ?
are any of them working ?
The fan generally comes off the 12V rail

have you connected the POWER_ON wire to 0V ? ... often a green or purple wire
are the cable connections marked on the PSU ... it may tell you which wire if the power on one
The PSU wot start up without doing that

is .... it's a 250w BEST the PSU brand name?

if not what is the brand name and or model ?

 

[Bluejets]

Units such as this usually wait for a pg (power good) signal from the pc.

 

[davenn]

Units such as this usually wait for a pg (power good) signal from the pc.

yeah ... power on aka power good ... take your pic

 

[jvdbossc]

I am not an expert, but already saved a few of pc's just by looking at the caps. In a lot of designs they are relied upon and fail. A lot of times you can see that they bulge or leak, or you get the "rotten fish smell". I would stop with powering it on and find the fault first.

 

[tedstruk]

melted insulation on this coil?

 

[tedstruk]

This is a good one!

 

[tedstruk]

The importance of fusing and breakers.... what kind and what size of fuse do I put in a PC power supply?

 

[tedstruk]

Got it out of there! Now how do I replace it!

 

[tedstruk]

there are 3 sizes of wire on this induction coil, and I forgot where each of them connect.... thats OK, I have ordered a new supply unit(PSU?) this is more like a project now!... can I use telephone wire to rewrap the coil?(wrong gauge is the wrong induction. What if I only need a couple feet of each?

 

[tedstruk]

There! thats better.. now back to my first question.... anything I should know before I hook it up to my o-scope?

 

[tedstruk]

Part 4. Testing...
Hay Harv.... wanna plug that power supply in for me!