Liteon PA-1650 Power Brick cold start issue

[Dumah Brazorf]

Hi,
I have this brick that sometimes not start. When it starts it works perfectly.
I measured the voltage out and found that it raises up but if it not reaches immediatly 19V it shut off, so for example the first time it reaches 12V and shut down, so if i hurry and pull out and in again the power cord it starts up to 19,2 and it works.
I tested the 2 470uF caps with a capacimeter and read correct, also the little 33uF near the main one. The main cap reads 108uF out of 120.

[rogfanther]

Re: Liteon PA-1650 Power Brick cold start issue

Cannot see it well, what is written in the main controler under the board ? Also, I believe you could try replacing the little cap between the main one and the transformer. Or maybe try heating it a little ( with a hair dryer, for example ) before plugging the psu and see if it works that way.

[Dumah Brazorf]

Re: Liteon PA-1650 Power Brick cold start issue

The IC is a 1D09903 5587

Changed the little one, although it seemed ok (33uF out of 33). Preliminary test is positive, I'll see better tomorrow.

[sam_sam_sam]

Re: Liteon PA-1650 Power Brick cold start issue

I would also change the two output as well

Because if you change the 33uf and seem to work better that what lead me to tell you to change the other two caps

[ben7]

Re: Liteon PA-1650 Power Brick cold start issue

Is this from an hp laptop PSU?

Yes I agree, change those output filter capacitors, and the high voltage one too, since these PSUs seem to run quite hot!..

[Dumah Brazorf]

Re: Liteon PA-1650 Power Brick cold start issue

I've burned something, now it shuts off after a second...

[ben7]

Re: Liteon PA-1650 Power Brick cold start issue

Did something smoke?

Check for broken traces, or check for broken solder joints.

What is the voltage across the capacitor you replaced? Test it as you are plugging the PSU in. (be careful not to let the probes slip, if they do they could short stuff out ... or else you could solder two wires on temporarily if you think your probes will slip off)

[Dumah Brazorf]

Re: Liteon PA-1650 Power Brick cold start issue

Nope. When i wrote it seemed to work i only had measured with a voltmeter. Today i used a pc and it shut off after a second.
Now it's worse. It does not start up at all. Zero to out caps. Even the little cap does not reach 19v and working out and in with the power cord does not make it rise. I've shorted the big one a couple of times!
This brick didn't work well since brand new. Sometimes didn't power up at all but when it did it always worked perfectly, as i wrote.

[ben7]

Re: Liteon PA-1650 Power Brick cold start issue

Is R31A OK? It looks a little scratched up.

Now that I have had a closer look, this is an odd PSU. The switching mosfet is driven by two transistors, instead of being driven directly by the controller IC, which is usually how it is done in these kinds of PSUs

[Dumah Brazorf]

Re: Liteon PA-1650 Power Brick cold start issue

I think you are referring to the two mosfets (that i tested and work) 1n60al drived by a second opto for shut down in case of short circuit in the dc out. They power the ic's pin8 through the 2,2k R5 resistor. The main mosfet's gate is directly connected to the ic. The circuit it's pretty different from the one in the 5587 datasheet.
Thanks for the help. I let it rest in peace. I'll use its parts for future repairs.