HELP.......!!! Antec Truepower 2.0 550W

[BaldiGit]

Hi all, I have an Antec Truepower 2.0 550W PSU which wouldn't start up. Took the cover off and found some erupting caps, so decided to replace the lot.
All went well until I tried powering up again...... Turned on the power and all is well. Applied the PSU tester and nothing, and then POP..!!! C44 exploded.
I have no idea why it went, I can only imagine I had the polarity wrong. Can't really tell though, as there is nothing left of it. So I replaced it and tried again. This time the PSU fired up ok, but I have no 5V.

I've obviously damaged something but not sure what. Would anyone have any experience with Antec's that could offer some advice?

It looks like C44 is directly connected to transistor/voltage regulator (TO- packaged), I might fish that out and check it next.

[PeteS in CA]

Re: HELP.......!!! Antec Truepower 2.0 550W

No +5V? Or no +5V Stby? You might look at the "health" of the PCB traces in that circuit and the health of the O/P cap and inductor for that O/P.

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

It was the 5VSB and the PG light that failed to light on my budget eBay (from China must be good) PSU tester. My intension was to fire it up with said tester then run along the contacts with DMM before I tried it on an old Mobo. But things didn't go to plan.

The PCB traces look ok although there are points of discolouration where a resistor has been a tad hot. But they where there before and I did read somewhere on this forum this is normal for that part of the board.

I've changed all the caps with exception of the large input one that checked out ok (and looked expensive). And all the inductors look ok, but I have no means of testing or values to test against....

Could it be the L7818CV voltage regulator attached to the now popped cap? I have it out but I'm not sure how to test it....

[goodpsusearch]

Re: HELP.......!!! Antec Truepower 2.0 550W

Some photos might help

[PeteS in CA]

Re: HELP.......!!! Antec Truepower 2.0 550W

The L7818CV looks like STMicro's version of a standard 7818 3-terminal regulator, You could find the datasheet online, connect 20V-24V to the input and see what you get at the output.

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

Not sure exactly what you want to see, but here's the offending area. I followed a post elsewhere where someone had pictures of the same hot spot. And the concensus of opinion was the above resistor was the cause it but all was well. I have resoldered said resistor as the joint looked a bit sad.

You can see from the top picture some of the debris of exploded cap (I must have had the polarity wrong...!!!). Needless to say this picture shows the replacement in position.

I have taken the L7818CV out in these pic's. And for £0.99 it might be worth a try at replacing it.

I've noticed that most of the pictures of this power supply have 2 medium size caps on the input. But mine has only one large one. Maybe it's the UK 240V as opposed to the states 110V...???

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

That sounds good advice.... But I haven't got a desk power supply at hand to get the 20-24v. Might just order one and try it.

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

Well that didn't work...... I tried a new L7818CV and it's still the same One thing I was wrong about though was, It's the -5V and the PG lights that doesn't come on, not the 5VSB. Also the fans don't spin, probably run from the -5V...!!! Any idea's would be most welcome.

[rogfanther]

Re: HELP.......!!! Antec Truepower 2.0 550W

Your PSU probably doesn´t have a -5V line. Does it have a white wire in the ATX connector ?
Take a look at that transistor near the cap you replaced . Also look for solder bridges under the PCB.

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

Oh yes.... No white wire. And I plugged in a good Antec Earthwatts 650w (also without a white wire) and no -5V So it's just the PG light and no fans...???

I've unsoldered the transistor and run it through a simple DMM test and it seems ok And I've even checked the signal diode in the hot spot, again ok. All the pcb tracks look ok too, I've had it under a big magnifier.

[John Doe]

Re: HELP.......!!! Antec Truepower 2.0 550W

https://www.badcaps.net/forum/attach...6&d=1333221799

That doesn't look good. It was probably regulating badly when those Fuhjyyu's went bad, and died after the second failure. It's an old PSU, just get a new one.

[rogfanther]

Re: HELP.......!!! Antec Truepower 2.0 550W

You could have soldered the cap backwards. It happens. Clean that points you call dodgy soldering, and test continuity from them to another point in the same trace. There could be some bad / intermitent contact there.

Also, measure the green wire. You may need to trace back the circuit from it and the PG wire.

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

I think I must have soldered the cap that went bang wrong. Which started me on this journey...

I'll check all the joints in question and near by caps. Good idea tracing back from the green, I'll have a look. But this circuit seems to be on the mains primary side, so not sure it's going to be that obvious.

[BaldiGit]

Re: HELP.......!!! Antec Truepower 2.0 550W

Ok... Checked all cap and there all the right way around. Stumbled on a dry joint and sorted that out. Fired it up and all lights come on and fan is now spinning. But after a couple of seconds the PG light goes out.... Have checked the voltages and all seem good. Traced the green wire back and it comes to a small daughter board. On which was a dodgy looking transistor and resistor, which checked out ok. But next to it was a TN431 Shunt regulator. That seems suspect (if you can believe http://www.jestineyong.com/how-to-te...gulator-tl431/). So I've ordered a replacement and we'll see.