Thermaltake ATX supply goes BANG! - TR2 RX-750

[bcstedt]

This is a new unit that has not been used before.

I powered this unit on using a jumper in the motherboard connector (grn to blk) and it seemed to work OK. I hooked it up to a PC and everything seemed fine for 10-15mins (load meter was showing power draw around 80-100W) and then there was a loud BANG like a firecracker or a gun went off. PC went dead and the supply was removed for inspection.

Initial inspection didn't reveal anything obvious but I did see a small black dot on the plastic insulator sheet underneath the main board. It appears that this mark is directly under one of the pins of the small transformer (details to follow).

Supply shows no signs of life and the fuse seems to test OK. Any idea where to start? Pics to follow.

[ReeceyBurger123]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

As the fuse is good, do you get 5v stby ?

[bcstedt]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Two of these pics highlight the dark-spot on the insulator sheet. It looks like it is centered close to Q7 (on the bottom) and the 3/4 contact of the smallest transformer, L5 (top reads: EE-10-02).

I do not see (or smell) any smoke-release point.

http://imgur.com/a/lykEH

[rievax_60]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Have a close look at the 8 pin IC in the standby supply live side. It looks like a PI brand part.

[bcstedt]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Just checked and I get 5.06VDC on purple (+5V standby).

[bcstedt]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

It certainly looks like a PI marking but it's a 7-pin (missing #3). It's a bit hard to read but it looks like:

PI 1119
TNY279PN
86905C

[rievax_60]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Sometimes the top blows off. It looks ok then? Is there STBY 5V present?

[stj]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

TinySwitch TNY279PN

[stj]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

there is a LOT of cracked solder joints on that psu!

[bcstedt]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

there is a LOT of cracked solder joints on that psu!

Must be the lighting, I don't see any from here.

[rievax_60]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

It is going to be difficult to go much further. All I can think of for now is to check for shorted power transistors on the live side. I can see the PFC transistors paralleled near the edge. I can't clearly see where the others are.

[everell]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Measure the voltage across the 400 volt input capacitor. If it measures 166 volts, the APFC (active power factor correction) circuit is not working. If it measures about 400 volts, the APFC circuit is working. Usually, if the APFC circuit is not working, the pwm section of the 6800 chip will not work. So measure across that big input capacitor and tell us your voltage measurement.

[RJARRRPCGP]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

I definitely notice a gap in the solder joint right under R7!

[Stefan Payne]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Can't really help but I have a nice photo of a similar Cougar 700W thingy, hope that helps kinda...

[Behemot]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Also check the input cap for bulging, the top is rounded. May be just the plastic but better be sure.

[locojack]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Hi! I have a this model and I had the problem that one of the resistances damaged me when producing an electric arc. I wanted to ask you if you can give me the value of the resistance that is in the so-called "R79" space, if you can take a clearer picture of it or the value, of course, thanks mate.

[stj]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

2.2ohms

[locojack]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

Change the smd resistor to a conventional one (it did not have smd) and it exploded again. The previous one also exploded, but apparently the problem is another, some idea? Thank you!

[stj]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

of course it exploded,
you didnt fix the cause!

[locojack]

Re: Thermaltake ATX supply goes BANG! - TR2 RX-750

The truth that without your comment I would not have noticed, you made a great contribution.