HP Power Brick

[rigeback]

Re: HP Power Brick

More concerned about the computer just now since I found one of my fans was not working and the mobo will circulate a direct 19V connection, cpu might be fried! I guess I should start a new thread it the problem persists. As for adapter I'm seriously considering ordering a new one.

[rigeback]

Re: HP Power Brick

Removed the start up cap today which of course is different to all the others since its a "Rubycon" in the bad list!

- If not zero volts, but rather the voltage goes up and down, change the start-up cap (usually a small 10uF, 22uF, or 47uF electrolytic cap on the primary side).

The rubycon cap is rated for 50V - 3.3uf, the only replacement I have is
50V -2.2uf, will this be safe to install??

[selldoor]

Re: HP Power Brick

"I've attached a schematic for this adapter"

Fooled me there for a while - I was going to look for this 3.3uf cap and spotted that according to the specs the adapter is only rated at 2 amps.

The schematic provided does not appear to be for this model ?

[rigeback]

Re: HP Power Brick

Yes sorry about that schematic I noticed that too after reading it, I can't find the schematic on Delta for this brick, and neither for HP ZD8270ea mobo, almost the same as ZD8000.
Anyways I went ahead and changed the cap and no change, as I last resource I might replace the fet as I got a few HP printer bricks that are scrap.
I found a new brick on ebay for 26 bucks + 13 shipping and then theres customs 23%, it's the only way.

[momaka]

Re: HP Power Brick

Removed the start up cap today which of course is different to all the others since its a "Rubycon" in the bad list!
The rubycon cap is rated for 50V - 3.3uf, the only replacement I have is
50V -2.2uf, will this be safe to install??

I somehow doubt this is the start-up capacitor. How did you determine this is it? I see 3 other small capacitors on the primary side. What are their specs?

Also, what's the voltage across the big Nichicon GU cap on the primary?

[budm]

Re: HP Power Brick

Try heating the power supply up with hair dryer for about 2~3 minutes first then plug it in to see if it will start up. ESR of the bad cap goes down when it is heat up.

[rigeback]

Re: HP Power Brick

I've tried heating the brick with hair dryer before plugging in the 240V but no joy,might not be hot enough, the main filter cap measures 315V, down loaded the spec for the MC33368 High Voltage GreenLine Power Factor Controller and probed pin 1 hoping to see 5V but instead it had 315V which seems a bit scary!
As for replacement of that cap I guess pulled the wrong one as saw the 47uf today after removing more glue, I have I have searched high and lowfor the data sheet of this brick but still no luck. Will try pulling the other cap tomorrow. Thanks for all the feed back.

[budm]

Re: HP Power Brick

That sounds like the PFC Voltage booster circuits are working, otherwise you will get about 165~170Vdc on that main filter caps.

[momaka]

Re: HP Power Brick

down loaded the spec for the MC33368 High Voltage GreenLine Power Factor Controller and probed pin 1 hoping to see 5V but instead it had 315V which seems a bit scary!

Whenever you're measuring on the primary side of a power supply, the negative probe on your multimeter should be connected to hot ground. Hot ground is everything connected to the (-) of the big Nichicon GU cap on the primary. This is different from regular ground. Hot ground is usually at -160V with respect to regular ground (0V).

So check you measurements again... put red multimeter probe on pin 1 and black probe on (-) side of the big Nichicon GU cap on the primary side. Also check the voltage on pin 12 and report back what you find.

That sounds like the PFC Voltage booster circuits are working, otherwise you will get about 165~170Vdc on that main filter caps

Not always. AFAIK, rigeback is in Italy, so he has 220-240V line voltage. In this case, a fully rectified mains there would be ~311-339 VDC.
On *most* power supplies, the APFC circuit *usually* keeps the voltage around 360-385 VDC (and sometimes as high as 400V if the primary cap is rated for 450V).

[budm]

Re: HP Power Brick

Well, he did not indicate which Country he is in, since he is only getting "the main filter cap measures 315V" that means the PFC is not working.

[rigeback]

Re: HP Power Brick

Confirm I am living in Italy and we have 220-240V. I have not replaced the 4.7uf-50V start up cap as the only spare I have is 4.7uf-25V which might make things worse!
As for the checks I have using the Negative side of the big main cap on all tests, big cap still tests 315V.

So check you measurements again... put red multimeter probe on pin 1 and black probe on (-) side of the big Nichicon GU cap on the primary side. Also check the voltage on pin 12 and report back what you find

Anyhow MC33368 pin 12 tested 7-12V fluctuating and pin 1 seems to have 5 Volts now.
I noticed that I don't have power on the last mossfet after D8 & R4 that feeds the flyback transformer, it was there before? The big Nichicon GU cap also looses its charge within seconds of pulling the plug, normally they take a few minutes to discharge?

[budm]

Re: HP Power Brick

I think you are getting close to where the problem is, since the VCC going up/down 7~12v, as you can see page 11 of the MC33368 on how the VCC for the IC is generated, and that cap C4 as shown in page11 may be the problem, and of course that cap will have different designator on your board. The circuits in the spec sheet should be real close to what you are working on.

[rigeback]

Re: HP Power Brick

Looks like it could be C5 on the brick as VCC on the schematic goes through a C4 which is a 100uf cap which is C5 100uf-35V, I was going to replace it but I only have a 25V version?

[budm]

Re: HP Power Brick

Since the spec of the VCC operating is 16VDC and transient is 20vdc, so I do not believe the power supply will be higher than the VCC, so just for testing you can use the 25vdc , but this cao must be low ESR type, the general purpose may not work but you can try just for now.

[rigeback]

Re: HP Power Brick

Changed C5 out but still the same no on the secondary side and no DC power out, I still think theres some thing wrong with the mossfet that switches the power to D8 as that mossfet is completely dead, I will try pulling R2 before taking the rest to bits.

[momaka]

Re: HP Power Brick

Check D2 with diode test function on your multimeter. It will usually show a reading one way but not the other.

[rigeback]

Re: HP Power Brick

Quick question..I got 2 resistors that I tested with 12.60V DC power supply, 1(R2) rated for 0.15 Ohms tested 0.19 Volts and the other (L6) rated for 1.5 Ohms tested 0.28Volts. For L6 I used a resistor calculator but there again should it be classified as a resistor??
D2 tests as a normal diode 390 Ohms one way and the other OL.
I still haven't managed to find a schematic for this brick must classified information I guess.

[momaka]

Re: HP Power Brick

Quick question..I got 2 resistors that I tested with 12.60V DC power supply, 1(R2) rated for 0.15 Ohms tested 0.19 Volts and the other (L6) rated for 1.5 Ohms tested 0.28Volts. For L6 I used a resistor calculator but there again should it be classified as a resistor??

Not sure what you were trying to do here with the 12V DC power supply. L6 is an inductor, not a resistor, as per the "L" prefix. In DC circuits, an inductor will appear to have very low resistance.

D2 tests as a normal diode 390 Ohms one way and the other OL.

That's good.

I attached a picture with some test points. With the power adapter disconnected from the wall, measure the resistance between each set of circle test points of the same color (ignore the blue arrow for now). For the orange test points, check with the diode test function (in both directions) instead of measuring the resistance. Ideally, you should get a diode reading in one direction and open circuit (OL) in the other.
Post your results here.

Finally, the blue arrow points to pin 2 of the PWM controller, which is a L6384D (a high voltage half bridge driver). Pin 2 is Vcc. Check the voltage on that pin (with respect to HOT ground) and post what you get. Be careful not to short anything there.

[rigeback]

Re: HP Power Brick

For the orange test points, check with the diode test function (in both directions) instead of measuring the resistance. Ideally, you should get a diode reading in one direction and open circuit (OL) in the other.

The Orange test points read 380 Ohms one way and OL the other.
The Red test points read full continuity both ways! This is L7 although it looks more like a diode than an inductor!
The Pink test points are full continuity both ways!

To test the Blue points R15 I have to solder in some parts including the main cap!

[rigeback]

Re: HP Power Brick

I'm considering buying a new 180W PSU on ebay but I'm not so sure about the mobo if sustained any damage when the PSU quit, the mobo DC plugging point does not short to ground but there were no signs power circulation, what would be the best trouble shooter before going all out, or would it be best to start a new thread in note book forum??