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

[Th3_uN1Qu3]

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

Lift 'em from the board. If they still read shorted or open on the diode test, they're bad.

[godonr]

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

Toasty - I can't ID the Q352 (post #50). There's something on the surface that makes any markings unreadable. Have any idea what it is?

[godonr]

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

Thanks Th3... that's how they were reading. Now I have to find a source for FQP7N80. I have 10 backordered @ Mouser but doubt I'll see them. Appears the path of destruction for the "R302" failure is F1 > R302 > Q301 & Q302 > C301 & C302 and sometimes C303.

[Toasty]

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

Q352 = 5bw = bc807-25

[godonr]

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

Toasty thanks again. There's something coating the solder side of my boards that makes it almost impossible to read markings.
Another question- Q302 is hard to get, closest I can find is a STP8NK80Z which has a much lower Pd than the original fairchild. Is that what you are using? All of mine only read with the DVM + on S and - on D (I know that's the internal diode). Everything else is OL on it. Problem is I can't really verify if mine are bad. On units where C301 and C302 failed, Q301 is shorted as expected. But my Q302s read the same on them and on the units where U801 was the issue, not the caps. Has me wondering if the Q302s might be OK. Any ideas on how to proceed?

[Toasty]

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

Where are you located? Q302 (FQP7N80) is plentiful....??

Mouser shows the FQP7N80C at 965 stock @ $1.57. Same device by the datasheets.

Toast

Oops! Forgot the coating. Use an (old style) ink pen eraser lightly across the surface to remove the flux residue from the soldering process on SMD's. You'll eventually get accustomed to how much pressure is needed to remove the coating.

If Q302 is not reading more than the internal diode (using diode check, correct?) then it's probably okay. MOSFETs seem to fail shorted in more cases than not.

[godonr]

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

Toasty -- just got notified today Mouser got the FQP7N80Cs in. I had some on backorder. Went ahead and ordered a few more... hope to get 25 supplies working with them.
The only way I have to test is with the DVM +on D, - on S to confirm open; move + to G briefly then back to D to confirm conduction. Reset with - to G and + to S. Unfortunately, the Q302s I have all read open everywhere except across the internal from S to D.
The Q301s are definitely shorted every which way! Guess I just don't have the right tool for the job reading the 302s... as you say they are probably OK.
Thanks for the tip on removing the film on the chips.

[vsp900]

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

Does anyone know what U704 is? I'd like to be able to find a data sheet on that component. I can see where a part number was on the chip, but the surface looks bubbled and there's no way I can read it.

If someone could give me a part number, I would greatly appreciate it.

[Toasty]

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

OV / OC Supervisor chip for 3.3v, 5v, 12v.

FYI - *NLA*

Weltrend, WT7517 S167

Toast

[vsp900]

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

Thanks, Toasty.

You always give reliable answers. I really appreciate it!

[godonr]

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

OK... new F1, Q301,Q302, C301, C302, good C303 restores +5vsb but no +12vaud, 3.3 or -12 on P1. Anyone have any ideas where to look next?

[tempo345]

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.

Hi Godonr,
Did u have any luck replacing TOP249YN, I am having the same issue with my powersupply, same face off from the U801. so seems its the same issue you had with your PSU. Can you let me know how you sorted it out?
Thx
Mitch

[godonr]

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

Have had mixed results when U801 blows. I was able to get two supplies going by replacing U801 (TOP249YN), C852 (47uf/25v), Q856 (MMBT2907A) and OPTO851. All are available... Mouser's one place. Still looking for ideas on the other problem when F1 goes. I have had three come back to life but have reached a wall lately on the rest.
Good luck and let me know if that gets you going again!

[godonr]

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

Back banging on some of these supplies. Have included pictures this time. Would like some ideas on where to look next after the already mentioned components have been replaced. Anyone have any ideas? Thanks

[Toasty]

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

3.3OC are the sense bars for over-current. Same for 5, 12v1, 12v2, 12v3.

How did you determine the OPTO was bad?

[godonr]

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

Have a huntron which will sig them... but really had replaced everything else on one supply with no luck so I tried the 851 (It had worked on a blown U801 once) and got everything back. Basically shotgunning at this point cause board has me confused.

[godonr]

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

Attached are two more pixs of the primary side. On a good supply, I see 350v on the cathode side and 52v on the anode. On a bad board with F1, Q301, C301 and C302 and R302 all replaced (obvious damage to all), I still don't get any voltage at D1. Source seems to trace to L4981AD shown on solder side picture. Is there a safe way to read it????

PS... Toasty, that last post about the opto (#76)... it fixed a board where U801 had blown. So far they are the easiest to fix.

[Toasty]

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

As I only have 1 to play with, I shelved this for the time being. I bought it just to see what I could determine, but also reached a wall where it sounded like it was going to fire, but doesn't.

Other, easier fixes are making money, so this will sit for awhile.

Toast

[godonr]

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

Toasty -- I can appreciate that. The blown TOP is an easy fix but the other is (F1, etc) tough. I think the problem is in the mains and may be the power corrector. I'm tracking a working one, printing out data sheets and hope to find something soon. I finally have a "spare" working supply I can make a mistake with and not worry about. As always, thanks for the input!

[Fallen Wolf]

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

Just wanted to leave feedback: I've given up on the broken supply here - mostly because I couldn't find some replacement-parts here in Germany (mostly the capacitors around R302 - shipping-costs from mouser and digikey to Germany are overkill...) and because I got a used-one in working-condition from Ebay

Hopefully the one from Ebay will last for a while.

I started to make a list of the parts on the board (attatched to this post - only some of the electrolytic-capacitors are listed and it's in German ^^ ), so if anyone may find this incomplete list useful, here you go

Thanks for all your help
Greetings from Germany
Wolfi