HP HSTNN-HA09 laptop power brick - power led turns off

[SuperDuty]

Hi guys,

I've just got this big laptop power brick (150W, 7.9A) for free, when I plug it, the power led is fully bright, then it starts dimming slowly and turns off after about 20 seconds.
I've just opened it, and all caps look good (mostly Chemicon and a small rubycon), it's not even three years old actually (48th week of 2009 on the PCB).

I was hoping to use it with my HP dv6 since it's an original HP charger.

I've checked the volatge at the plug, it goes from 19V and gradually goes down to zero...

What voltages should I check first ?

Thanks !

[Khron]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

I'm actually in an identical situation, i just hadn't got around to actually posting about this yet.

[joshnz]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

My guess is the start up cap has dried out.

[Khron]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Worth a shot, i suppose. Although i hope i'll get around tonight to tracing the circuit that leads to the "Sense/ID" pin...

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Is the start up capacitor a yellow rectangular plastic capacitor ?

[Khron]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

No, it's one of those two small electrolytics near the PWM chip. The yellow rectangular (plastic) cap is part of the noise filter on the AC input.

[selldoor]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

A picture would be good? Kron 666 must know what its like but the rest of us might like to learn.

[Khron]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

It's most likely "drowned" in some of that white silicone / RTV goo. There's two small electrolytics near the top of the main capacitor (120u/420v). A 47u/50v and a 22uu/50v, both Rubycon YXF.

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Okay, there are two small lytics just above the main cap, they're both Rubycon YXF, one is a 50V 47uF, the other is a 50V 22uF. Are these the start up caps ?


You can see the two small caps here, the 22uF one is buried under the glue :

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Okay I've just changed the two small caps, and the big cap but with no change...

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Replaced the three 25V 1000 lytics with 25V 820uF for a quick tests and it still shuts down the same way, so it's not a lytic cap problem

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

I've just checked the voltages at the two small capacitors, I get constantly changing random voltages from 15 to 20V !

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Tried changing the blue disk ceramic cap...no change :/

[ben7]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Well, try changing the secondary caps, chemi-cons sometimes don't like heat.

If that doesn't work, try putting a load on the power supply when you plug it in.

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

The secondary caps are the three caps on the far right next to the output cord right ? Then I've changed them already...

When you mean, putting a load, do you mean pluging it to a computer ? If so, I do all my test this way...but now I've just tried it a couple more times and it stays on a little longer, for about a minute or two, but then it shuts down the same way. The problem is I don't know if the computer works, it gives a few signs of life though.

[ben7]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

The secondary caps are the three caps on the far right next to the output cord right ? Then I've changed them already...

When you mean, putting a load, do you mean pluging it to a computer ? If so, I do all my test this way...but now I've just tried it a couple more times and it stays on a little longer, for about a minute or two, but then it shuts down the same way. The problem is I don't know if the computer works, it gives a few signs of life though.

Yes by load I mean something that would draw power from the power supply.

Try checking the secondary side rectifiers,.

Also check what voltage shows up at the big brown mains cap when you plug it in and when it turns itself off.

[Khron]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

Ok, i *think* i've managed to lift the schematic of the secondary. As far as i know, it's pretty much correct, to the best of my abilities, although it MIGHT look a bit confusing.

https://dl.dropbox.com/u/20127094/Eagle/Hipro_sec.gif

IC1 = UM603A (dual opamp & 2.5v reference)
IC2 = TEA1761 (active rectification controller)

The TEA1761 part of the circuit is exactly the schematic that's on page 3 of the linked application note. I've used the numbering from the board itself, and the resistor values are the ones i managed to read off them (the smaller ones seem to have the EIA96 type markings, two digits and a letter).

I'm not 100% positive i "decoded" the top-most transistor correctly, though. Most references i've found pointed to a PNP (MMBT3906). If someone could make sense of what the ID/Sense pin is supposed to be doing, it'd be quite interesting to know...

[SuperDuty]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

I think it's the pin used by the computer to recognize it is an original HP charger.

I'll check the voltages and get back to you.

[Khron]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

The thing i'm wondering is, is the laptop providing some sort of "turn on" voltage/signal to the PSU, or is the PSU giving some "signal" to the laptop...

[ben7]

Re: HP HSTNN-HA09 laptop power brick - power led turns off

The thing i'm wondering is, is the laptop providing some sort of "turn on" voltage/signal to the PSU, or is the PSU giving some "signal" to the laptop...

I think the PSU is giving a signal to the computer, seems that it makes an oscillating signal with the op-amp and amplifies it, then sends it to the computer.