Need Help Thermaltake Litepower 500W Problem

[sonicunderground]

Hello everyone,
PSU: Thermaltake Litepower 500W Model: LT-500AL2NC
PCB: G08-CGPA462-PA00 Rev:A
I have this PSU installed in my PC for several years.
The problem is one day my PC cannot detect an external HDD so i think maybe the PSU caps already bad.
So i decided to open the case and found some of the secondary caps already bulging.
Then i recapping all the caps except the primary one (because i tested it with an esr meter and its still good) and i already tested all the new caps too before i soldered them.
After that the psu is good and my pc can detect my external HDD.
But 1-2 days later, when i using my pc suddenly i hear a clicking sound from the psu several times and then my PC turned off (about 5-10 min after the sound).
Then i removed the psu and tested it with psu tester and a light bulb (100W) in series with the AC mains.
Guess what, the light bulb shine brightly (something shorted!) and the psu fan spinning and i got all the voltage readings correct but only for a moment (about 1 min) after that all the voltage readings become 0 and only the 5vsb output remains.
So i open the psu again and start looking for the problem.
I tested the mains rectifier and all the diodes and it's all good.
I tested the filter safety caps OK, ZNR OK, Thermistor OK, Resistors in primary side OK.
I removed all the heatsink,tested the components and found the problem.
One of the 13N50 Mosfet in the middle heatsink is shorted and the PFR30L45CT diode in the secondary heatsink also shorted.
Then i decided to replace them but i cannot find the exact same parts in the local electronics store.
So i looked for similar parts and replaced all of the 13N50 with 15N50 and replaced PFR30L45CT with MBR30100PT.
After soldered all the parts and cleaning the PCB, i tested it again.
And now the AC mains light bulb is only flashed for 1 sec (charging the primary caps) and then turned off.
BUT, i still only got 5vsb readings on my psu tester.
So i decided to open the psu again (and again) looking for another problem.
I removed the KN2222A,KN2907A,TL431K,2SC1384L and found no problem.
I removed the PC817 opto and found one of them is bad, replaced all 3 of them with a new one.
But still no luck, all i got is only 5vsb output.
So, i wanna ask everyone here for help and maybe one of you have similar psu and know the problem.
I'm not an expert at electronics but i want to learn more about it.
Thanks in advance for your help.

[RJARRRPCGP]

Re: Need Help Thermaltake Litepower 500W Problem

First photo: Too much flash glare!

[Quaddro]

Re: Need Help Thermaltake Litepower 500W Problem

Question:

1. After you replace all the broken/shorted components, have you tried to running it without ac line light bulb?
2. After you test it with direct line from ac outlet, try to jump start it.
Is the fan twitching..?

If it's not.. then problem is in (mostly) primary site.
If it's twitch.. that's mean everything in primary site is working, the problem is in secondary.


This psu is identical with enermax naxn 500..
i have repaired few of that psu.
And according to my experience, 2 resistor near the bulk caps, with value of 1 m ohm is open.

But if you already make sure all the components is checked, try to replace pfc ic, cm6805 and or supervisor ic st9S313.

[momaka]

Re: Need Help Thermaltake Litepower 500W Problem

Another day and another APFC design with issues likely to do with the APFC circuit.

What brand is the big cap on the primary and what voltage? If it's not a well-known Japanese brand and not rated for at least 420V (preferrably 450V) then replace with a Japanese cap rated for 450V and same or slightly higher capacity.

Check Source resistors on the APFC MOSFETs as Quaddro suggested if one of the 13N50 MOSFETs was really blown (by the way, did you check the old parts as you removed them out of the circuit? If a part reads bad in circuit, don't assume that it really is until it is tested out of the circuit.)

Last but not least, 100W incandescent light bulb might not be enough for series line testing because of APFC circuit. Use at least 3x 100W bulbs (bulb in parallel to each other) - and better if they are halogen type, as they will allow higher pulse currents, which is needed for APFC. Alternatively, use a 300-700 Watt heating element (hint: a toaster would likely do as well if you hold down the slider to turn On the toaster.) Either of these methods should allow APFC to work more normally.

You may also need sufficient load on the PSU for it to regulate the output voltages properly. So using several 10-20W 12V incandescent bulbs on the various output rails (3.3V, 5V, and 12V) may be needed.

[sonicunderground]

Re: Need Help Thermaltake Litepower 500W Problem

First, thanks for all your help regarding my problem,really appreciate it.

Question:

1. After you replace all the broken/shorted components, have you tried to running it without ac line light bulb?
2. After you test it with direct line from ac outlet, try to jump start it.
Is the fan twitching..?

If it's not.. then problem is in (mostly) primary site.
If it's twitch.. that's mean everything in primary site is working, the problem is in secondary.


This psu is identical with enermax naxn 500..
i have repaired few of that psu.
And according to my experience, 2 resistor near the bulk caps, with value of 1 m ohm is open.

But if you already make sure all the components is checked, try to replace pfc ic, cm6805 and or supervisor ic st9S313.

1.Yes, i tried to running it with direct ac line and still no sign of life.
2.When i jump start it the fan not moving/twitching at all. Tried with PSU tester and just got the 5vsb output.

Do you mean the 2x 1M resistor in series near the bulk caps? yes the 2x 1M resistor near the bulk caps is fine.

About those ic, i dunno how to test it because i don't have any spare ic like that.

Another day and another APFC design with issues likely to do with the APFC circuit.

What brand is the big cap on the primary and what voltage? If it's not a well-known Japanese brand and not rated for at least 420V (preferrably 450V) then replace with a Japanese cap rated for 450V and same or slightly higher capacity.

Check Source resistors on the APFC MOSFETs as Quaddro suggested if one of the 13N50 MOSFETs was really blown (by the way, did you check the old parts as you removed them out of the circuit? If a part reads bad in circuit, don't assume that it really is until it is tested out of the circuit.)

Last but not least, 100W incandescent light bulb might not be enough for series line testing because of APFC circuit. Use at least 3x 100W bulbs (bulb in parallel to each other) - and better if they are halogen type, as they will allow higher pulse currents, which is needed for APFC. Alternatively, use a 300-700 Watt heating element (hint: a toaster would likely do as well if you hold down the slider to turn On the toaster.) Either of these methods should allow APFC to work more normally.

You may also need sufficient load on the PSU for it to regulate the output voltages properly. So using several 10-20W 12V incandescent bulbs on the various output rails (3.3V, 5V, and 12V) may be needed.

1.Primary cap is JunFu 220uf 400v. Already tested it using esr meter and got 270uf capacity and 0 esr.
2.Yes, i already tested those resistor and it's still good. I always removed any components before checking to make sure there isn't any false readings.
3.I already tried to running it with direct ac line and still got the same result, so i don't think the bulb is the problem for now.


UPDATED:
I tried to jump start the psu and now i got readings about 80v in the 5vsb line!
I really don't have an idea whats happening anymore.

[RJARRRPCGP]

Re: Need Help Thermaltake Litepower 500W Problem

UPDATED:
I tried to jump start the psu and now i got readings about 80v in the 5vsb line!
I really don't have an idea whats happening anymore.

Yikes! Looks like a true PC-killer!

Litepower series placed in my ban-on-sight list!

[Quaddro]

Re: Need Help Thermaltake Litepower 500W Problem

UPDATED:
I tried to jump start the psu and now i got readings about 80v in the 5vsb line!
I really don't have an idea whats happening anymore.

80V?
woahh, i've never seen anything above 15v in 5vsb rail..

Check your tny176/tny177, try to replace it with tny 277.
and check all diodes surround it..

[momaka]

Re: Need Help Thermaltake Litepower 500W Problem

I tried to jump start the psu and now i got readings about 80v in the 5vsb line!
I really don't have an idea whats happening anymore.

Sounds like either you're using the wrong (primary-side?) ground or your multimeter is faulty/finicky. 80V on the 5VSB shouldn't be possible... well perhaps if there is a primary-to-secondary winding electrical leakage, but that's extremely unlikely. Pretty sure hi-pot testing at the factory would have caught that early on.