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**Agent24** · 11-06-2013, 10:22 PM

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

Originally posted by wasureppoi View Post

I bought a Q856 which I read was MMBT2907A SOT -23. This is about half the size of a lady beetle and a smidgin beyond my soldering prowess. Is there another type ?? I should have gotten?

Don't let SMD parts put you off, they're actually pretty easy once you get the hang of it, despite how tiny they look. Practice on some scrap boards first and you'll see.

The secret is proper technique and good quality flux. You can never use too much flux! - get some genuine stuff, not fake Kester pens from eBay for $1.50.
Also helps if you have small diameter solder, like 0.3mm and 0.4mm. The cheapest place for this is probably eBay, but it can vary in quality dramatically, although overall it usually works fine.

For those SOT-23 transistors, a fine-point tip for your iron works great, although it doesn't have to be super fine. I found it's more important you have lots of flux but not too much solder. See here for good instructions on how to do it: http://www.youtube.com/watch?v=iQujMK_rju0

Good quality tweezers (with proper tips) help tremendously.

Make sure you use some solderwick and clean the pads after you remove the old part, a bump of solder on the pad will make it harder.

**wasureppoi** · 11-07-2013, 01:49 AM

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

I find your comments inspirational. Sometimes if I havent already burnt the hell out of the pcb trying to clean up the excess flux I still cannot see the trees for the brown goo. Never quite sure what solder to get with varying tin percentages but settle for the smallest diameter solder available which may still be bigger than you suggest. Any particular brands you recommend would be appreciated. Will be studying the youtube link on soldering thanks. Do have good tweezers though 2 out of 10!

**wasureppoi** · 11-07-2013, 01:57 AM

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

Not sure where I gleaned it but someone had referred to the MMBT2907A or Q856 as bc557. The bc557 looks like a much easier chip to work with. Is that familiar to you?

**godonr** · 11-07-2013, 05:03 PM

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

if you are asking me... i'd suggest you look up the data sheets. Q856 (MMBT2907A) is a PNP power amp switch which as i recall feeds the optocouplers. BC I think is a Siemens designation. A check of data sheets would tell you if they are compatible.

**Agent24** · 11-07-2013, 05:45 PM

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

Originally posted by wasureppoi View Post

I find your comments inspirational. Sometimes if I havent already burnt the hell out of the pcb trying to clean up the excess flux I still cannot see the trees for the brown goo. Never quite sure what solder to get with varying tin percentages but settle for the smallest diameter solder available which may still be bigger than you suggest. Any particular brands you recommend would be appreciated. Will be studying the youtube link on soldering thanks. Do have good tweezers though 2 out of 10!

Try some proper flux cleaner or some 95+% isopropyl alcohol. If the flux is leaving a lot of brown residue it's probably heavily rosin-based. A little brush to loosen the flux and some Kimwipes or other lint-free material is good for cleaning up. See http://www.youtube.com/watch?v=BzJSbEi9YOo

For SMD, the liquid no-clean stuff is much better, such as http://nz.element14.com/chemtools/ct...n/dp/182777601 which is what I am using currently.

60/40 solder is what I prefer, 63/37 will also work but it feels a bit different if you're used to 60/40. Problem is, getting it and getting it in small diameters is difficult or expensive.
eBay\DealExtreme etc is very cheap but quality can be questionable. Farnell etc do sell it but it's not cheap. Jaycar has good 60/40 fairly cheap but the smallest is 0.7mm. It's usable for the bigger parts, but the smaller stuff is far easier, especially if you are doing something like 0603 resistors.

'Multicore' solder is a good brand, so is the stuff Jaycar uses which I believe is from a company called Consolidated Alloys. http://www.cagroup.com.au/Cored_Solder_Wires.asp

Lead-free will work if it's all you've got, though luckily(?) I haven't used any so far. Though there are several types of Lead-free solder. I am not sure which would be the best. Some of the older Lead-free types I think had problems with tin whiskers far more than the newer mixtures, but I may be wrong.

**wasureppoi** · 11-07-2013, 06:37 PM

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

Originally posted by godonr View Post

if you are asking me... i'd suggest you look up the data sheets. Q856 (MMBT2907A) is a PNP power amp switch which as i recall feeds the optocouplers. BC I think is a Siemens designation. A check of data sheets would tell you if they are compatible.

Sorry I thought I was addressing and asking you. Thanks. Even though I am damn sure the power amp switch is NOT PLUG N PLAY I am none the wiser with the PNP meaning yet. Must confess also that sometimes data sheets are not things I can readily understand. One wonders how I have not zapped myself already but exercise the greatest care I can.
If I can just work out how and where to use the MMBT2907A - Q856 tiny tiny chip that I have I will get my show on the road hopefully to a working PSU. One thing though I did using two atx psu's basically providing the power that the LITEON 6601 pinouts suggest but could not get any sign of life out of an otherwise immaculate looking mobo. Had to use 2 serially attached 12V batteries for the 24V . Off the top of your head would you say that is feasible? Just cannot believe this mobo is dead.

**wasureppoi** · 11-07-2013, 06:45 PM

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

Again prolific thanks. Hope I can implement some of the sound advice you have given.

**Agent24** · 11-07-2013, 06:54 PM

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

PNP is a type of Bipolar-Junction Transistor or BJT. There is also an NPN type.

http://www.allaboutcircuits.com/vol_3/chpt_4/1.html describes them.

**godonr** · 11-07-2013, 08:05 PM

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

what makes you suspect the p/s? here's a quick check. power off and unplugged, remove P1 from motherboard, plug good power cord back in (do not turn on computer). should read +5vstb between pin 1 and pin 23. this trickle power is essential for logic board to power on. somewhere in this info Toasty has posted a diag of the pinouts. also, don't overlook resetting the PMU.

**wasureppoi** · 11-13-2013, 06:54 AM

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

It was a Herculean effort but I removed the psu when I got no life signs. When I discovered the U801 chip had blown its face I was optimistic replacing it and the cap adjacent to it which looked good anyway. Unfortunately there was still nobody home. I shorted out the power good green and common. Since then I have replaced the Q856 and OPTO851 which proved OK but OPTO853 was stuffed. Anyway whilst no fireworks still no signs of life like spinning fans on psu. I have replicated the power to the mobo and it also appears dead as a door nail. I have a couple of mosfets that people had mentioned yet to put in and was going to replace one of the big caps for the heck of it.

**godonr** · 11-14-2013, 05:12 PM

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

Wish you the best. You are about as far as most have gotten with this supply... going where no tech has gone before so to speak... mostly because it became not necessary. But, would like to know if you are successful. best of luck

**6l6gc** · 11-14-2013, 06:20 PM

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

Nice to see this thread isn't completely dead. Listed below is my BOM (accumulated through this thread), which I intend to order from Digikey Canada.

Before I submit the order, does anyone see anything obviously out of place as far as these part numbers go? My TOP has no obvious visual damage and electrically doesn't suggest any signs of a short circuit. I will change the startup cap anyway.

All the other parts listed here have suffered visible or test-evident damage. I have had this PSU apart for months now and this thread has been the only useful one I have stumbled across. Thanks to everyone who has posted information whether this repair works or not.

1 Qty 4 - 399-6018-ND CAP FILM 0.1UF 630VDC RADIAL C301, C302
$7.52

2 Qty 4 - 283-3875-ND FUSE 10A 250V T-LAG CERAM AXL F1
$7.88

3 Qty 4 - 985-1004-1-ND RES 100 OHM 2W 5% AXIAL R301 4
$1.04

4 Qty 2 - SPW17N80C3IN-ND MOSFET N-CH 800V 17A TO-247 Q301
$15.08

5 Qty 2 - FQP7N80C-ND MOSFET N-CH 800V 6.6A TO-220 Q302
$3.90

6 Qty 2 - 478-1910-ND CAP TANT 47UF 10V 10% RADIAL C852
$3.72

7 Qty 4 - BC807-25WDICT-ND TRANS PNP BIPOLAR 45V SC70-3 Q352
$1.28

8 Qty 4 - MMBD701LT1GOSCT-ND DIODE SCHOTTKY 200MW 70V SOT23 D355 $1.64

Subtotal $42.06
Shipping $8.00

**godonr** · 11-14-2013, 07:42 PM

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

Did R302 burn? If it did, I recall F1, R302, Q301, Q302, C301, C302 and C303 (.47uf, 400v pulse film cap) worked. I had so many at the time, if the obvious didn't get it I just went on to the next. Glad this site has helped. Did you look at Mouser.com. Bought my parts there in 2011. Much cheaper. Keep us posted on your results.

**6l6gc** · 11-14-2013, 08:16 PM

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

Yes, it looks as if Q301 shorted, caused R302 to burn up, took out F1, caused damage to C301 and C302 due to their proximity to R302. Possible heat damage to the Schottky and the PNP Transistor. Q302 and C303 appear ok electrically (but I should've ordered C303). I will try to document the repair process with photos when the parts arrive.

**godonr** · 11-14-2013, 09:02 PM

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

This is the most promising of the repairs on this supply. good luck

**wasureppoi** · 11-20-2013, 06:57 PM

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

Originally posted by Toasty View Post

Ebay has them from Hong Kong.

T

Hi,
Looking on Ebay here nothing comes up and even www.ebay.com.tw
reveals nothing. Do you think you would be able to send me a link or do you think they are all long gone?

Regards,

**Toasty** · 11-20-2013, 09:38 PM

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

http://www.ebay.com/itm/190798671136

http://www.ebay.com/itm/120920844464

http://www.ebay.com/itm/110990867455

**wasureppoi** · 11-20-2013, 10:39 PM

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

Beg your pardon. Wish I had those links earlier but managed to get the chips I sought but I had read your post out of context and thought you were referring to complete PSU's! Thanks anyway.

**keithf2** · 09-29-2014, 11:52 AM

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

Are any of these threads still open

**Toasty** · 09-29-2014, 05:37 PM

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

Threads are always open, unless a flame war erupted and the admin closed it with rusty nails. LOL

Provided it's on topic, we'll gladly jump back in.

T

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