Rexpower PL-400 rebuild

[shovenose]

Re: Rexpower PL-400 rebuild

You didnt overrate it enough. Turn it into an "okia 900w" lol.

But seriously, whats with the 10a 12v rail, you need to improve that.

[c_hegge]

Re: Rexpower PL-400 rebuild

The 12V diode pack is actually rated for 30A, so it could probably do more.

[goodpsusearch]

Re: Rexpower PL-400 rebuild

I think it could do ~20A.

[c_hegge]

Re: Rexpower PL-400 rebuild

Revised label

[c_hegge]

Re: Rexpower PL-400 rebuild

OK. I powered it on. 5vsb came right up at 5.06v, however, I put it on a PSU tester and nothing happened, no power on, but thankfully, no explosions either.

[goodpsusearch]

Re: Rexpower PL-400 rebuild

Did the psu fan move for a second?

[c_hegge]

Re: Rexpower PL-400 rebuild

No. Absoloutley nothing happens on the tester. Fan doesn't twitch or anything.

[momaka]

Re: Rexpower PL-400 rebuild

Since 5vsb is there, see if there is some voltage on the PS-ON signal. There should be close to 5v I think.
Check for short circuit on all of the rails to ground as well. If none, check for short circuit between the rails themselves.
Also, did you replace the original 12v fast rectifier with a schottky? That could certainly be it.
Lastly, the PSU tester may not be providing a big enough load. If you have an old computer you don't care about or any hardware you don't care about, attach it to the PSU to give it a better load.

[c_hegge]

Re: Rexpower PL-400 rebuild

PS-on is 4.72v. I replaced the 12v fast recovery with an ultrafast recovery. It looks like the 5 and 12v rails are shorted both to ground and to each other. The 3.3v rail shows about 10 ohms to ground. Why would both be shorted??

[POM_MJ]

Re: Rexpower PL-400 rebuild

Did you've forget some isolator?

[c_hegge]

Re: Rexpower PL-400 rebuild

Fixed that and still no go.

[c_hegge]

Re: Rexpower PL-400 rebuild

OK. I found a solder blod shorting the 5vsb with another trace. I removed that and my DMM no longer shews the 5v as being shorted to ground. I'll have to look at the 12v some more when I get home from work.

[370forlife]

Re: Rexpower PL-400 rebuild

Did you replace the primary transformer with a different one? I don't know why, but sometimes they may be pin compatable but it will not work in other power supplies. Have this problem with a "35" sized transformer out of a keerda. Will not work in my Yue-Lin or my Golden Tiger. Golden Tiger's works in the Yue-Lin though and vice versa.

[c_hegge]

Re: Rexpower PL-400 rebuild

Yes, I did swap the primary transformer as the orignal was only a size 33.

[370forlife]

Re: Rexpower PL-400 rebuild

I should say both the Yue-Lin and Golden Tiger display the same problems, only 5vsb but they refuse to power up.

[c_hegge]

Re: Rexpower PL-400 rebuild

I removed the main transfromer, but still the short on the 12v persists. What should I look for next? I can't find any evidence that the solder is shorting the rail.

[Th3_uN1Qu3]

Re: Rexpower PL-400 rebuild

I removed the main transfromer, but still the short on the 12v persists.

Take out the rectifier diode.

[POM_MJ]

Re: Rexpower PL-400 rebuild

Take out the rectifier diode.

Yes, possibly your rectifier was gone.

[momaka]

Re: Rexpower PL-400 rebuild

Take out the rectifier diode.

+1

Also, it looks like you used thermal compound between the diodes/pads and pads/heatsinks - this is unnecessary. Moreover if the thermal compound is conductive, this could be the problem as well.

[shovenose]

Re: Rexpower PL-400 rebuild

you should use either real non-conductive thermal pads or nothing at all - depends how the psu was designed.