LiteOn PA-6601-1A (600w) blows its TOP

[godonr]

Have several 600w power supplies which have taken out a TOP249yn upon power up. Just blew the face right off each one with no other signs of heat or damage. This supply is used in PMG5. Anyone had a similar experience? It's marked U801.

[stj]

Re: LiteOn PA-6601-1A (600w) blows its TOP

topswitch often usees a small electrolytic to start running.
often 22 or 47uf.

always replace it, and use a good 105' type.

if the cap drops in value the top will pulse and you will hear a tick sound.
if you leave it long enough it will explode.

i'v had to fix dozens of these in satellite boxes.

[Toasty]

Re: LiteOn PA-6601-1A (600w) blows its TOP

PMG5 = PowerMac G5 ?

Please don't use "code". Someone looking for or having useful information would not find this thread.


Toast

[godonr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

Sorry, it's a PowerMac, Toasty. The Apple part # is 661-2904. I know someone posted on one before but didn't follow through.
Question for stj -- the topswitch does have a TAICON 47uf/25v cap as you describe. Are chances good just replacing it and the TOP249YN will fix it? Also, I have some which have blown the R302 (100ohm/2w) resistor by the L301 transformer. No signs of heat or burning. Any ideas would be appreciated. Thanks.

[stj]

Re: LiteOn PA-6601-1A (600w) blows its TOP

always replace a startup cap when you work on something.

if the top blew you need to check any diodes & resistros too.

in the stuff i was fixing, when the top went it took the fuse, a fuseable resistor and sometimes other stuff with it.

[godonr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

Do components, like the SMDs, need to be unsoldered to get a good read? I have access to a Hunter Tracker which is pretty good but also from before SMDs. It bothers me that I have the same failure on a number of supplies but nothing other than an obvious blown component to show for it. Where do you start looking? The TOP obviously took a shot of current from somewhere, right?

[stj]

Re: LiteOn PA-6601-1A (600w) blows its TOP

if you have a capacitor or esr meter then start with the small cap - i bet every damned blown supply has a bad one.

[godonr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

The Hunter reads caps, just not sure it's esr quality. Should I pull the caps to get a good read?

[stj]

Re: LiteOn PA-6601-1A (600w) blows its TOP

yes, they arent worth keeping.

[godonr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

I'll start pulling and testing. I'll keep you posted and thanks for the direction. Should be able to get something going. Thanks

[stj]

Re: LiteOn PA-6601-1A (600w) blows its TOP



may help.

[godonr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

Attaching some pixs from supplies I've been working. Two basic problems- on some the F1 and R302 (2w/100ohm) resistor fail; the other U801 a TOP249YN blows the face off and no other apparent damage. I've been looking at HS2 which has two MOSFETs (Q301 & Q302). Q301 is a 17N80C3 and Q302 is a FQP7N80. Q1 and Q2 are 20N60C3s and D2 is a STTH8R06D rectifier. I have to pull from a parts board for replacements so I'm wondering if there's any way to test them on the board. My desoldering equipment leaves something to be desired. Anyway, with a DVM Q301 doesn't appear to turn on/off on boards that blow F1 and 302. Is that the kind of dead short that would take them out? I'm hoping the attached pixs might provide some ideas and direction to look. Any testing techniques also would be appreciated. Biggest issue so far is desoldering stuff without damage.

[madamorr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

Any update on your fixing this power supply? I have the same problem of F1 and R302 failing. My TOP looks fine and the caps are not swollen.

What could cause R302 to fail?

Hos did you remove the transformers when the solder is on both sides of the board. The pins are buried under the transformers making them difficult to remove the solder.

Thanks,
Michael

[stj]

Re: LiteOn PA-6601-1A (600w) blows its TOP

the startup cap on a top will not look bad.
but it will go bad.

meter the top to see if any pins are shorted together - it could be that the 100r resister blew first before the top could explode.

[madamorr]

Re: LiteOn PA-6601-1A (600w) blows its TOP

Should I remove the TOP from the power supply for testing?

Thanks,
Michael

[Quasar]

Re: LiteOn PA-6601-1A (600w) blows its TOP

No real way to test it except to see if it's shorted. Better to follow the path R302 is in and see where it leads to. I suspect it is connected to Q301 somehow. That may be the problem device.

Take a pic of the back of the board at R302 so we can see what or where it connects to. Something like the 3rd pic from godonr did above, only on the back. Are there any devices mounted on the bottom of this board?

[chrjohnso]

Re: LiteOn PA-6601-1A (600w) blows its TOP

I'm working on 3 of these LiteOn power supplies. Two have F1 blown, R302 burnt and Q301 is bad. Both had a significant amount of dust inside. The third has blown F1 and Q301 and Q302 are bad. The bad MOSFETs show short between the drain and source (pins 2 and 3). I am attempting to locate a suitable substitute for Q301, as the 17N80C3 part seems to be obsolete and is not stocked at mouser or digikey.

[jf1452]

Re: LiteOn PA-6601-1A (600w) blows its TOP

I've just had one of these in to repair as well. U801 (TOP249) blown it's top, I checked C852 (47uF/25V); it tested OK, but I replaced it to be on the safe side. Powered up, and nothing!
I removed the board, and then did some more investigation. I have located transistor Q856 (MMBT2907A) which had gone open circuit between base/emitter, and short circuit between base/collector. I have ordered a replacement, no other components seem faulty. I'll update this once the new transistor has been received and fitted.

[vsp900]

Re: LiteOn PA-6601-1A (600w) blows its TOP

I'm in the process of fixing my Liteon PA-6601-1A as well. On my power supply, Q301 was shorted, which caused R302 to burn and F1 to blow. I also found that C301 and C302 were both burned. I was able to find replacements for Q301, C301, and C302 at Digikey, but I'm not quite sure what to replace R302 with. It is marked 100 ohm - 2WJ - 534. I located some 2 Watt 100 ohm resistors with +-5% tolerance. I think the "J" marking reflects 5% tolerance. It appears to be a wire wound resistor, but I'm not certain. Does anyone know if this is a wire wound resistor and if not, what type is it. Furthermore, would it really matter which type I replace it with?

I also found that the processor cooler is leaking and the coolant is crystallizing around the processors. This could be the cause of the blown power supply. I'm going to attempt a fix for this, including new o-rings and some sort of high temp silicone sealant on the outside of the o-rings. Hopefully, it didn't take the logic board with it when it blew.

Also, in case I find other problems in the supply, does anyone have a schematic and/or component list for this power supply? I haven't been able to find one online and haven't attempted to contact Liteon (probably a futile effort).

[Toasty]

Re: LiteOn PA-6601-1A (600w) blows its TOP

It's a fusible resistor.

http://search.digikey.com/scripts/Dk...e=PPC100DCT-ND

>>This could be the cause of the blown power supply.<<
It -could- be the cause, but I've had them with no leaks fail the same way.

>>does anyone have a schematic and/or component list for this power supply<<
No schematics unless you want to draw one....
Components should be easy as most are readable. Any questions on a specific component, just ask here.

LiteOn will not release schematics. It's all proprietary.

Where did you find Q301?

Toast