HP 15-AC135NA Dead

[Andyd1970]

Hi Guys,

I have a HP 15-AC135NA that is dead, first I found the chargers pin was bent so straightenened that and tested it in another laptop, all OK, I noticed DC jack was damaged so replaced it with new one, but still it is dead. I have limit experience on laptop motherboards, but following tracks from where power connector is I have found two caps/resistors that are short circuit. Not sure if I am right or not, I have highlighted them in one of the pictures. Any help would be great.

[piernov]

Re: HP 15-AC135NA Dead

Do you get white LED next to DC-in connector?

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, No the light is not on, I have 19v from charger and 19v on the connector on motherboard so I know it is getting to the motherboard.

[piernov]

Re: HP 15-AC135NA Dead

Check voltage on the AD_ID pin, the one connected to the center pin of the AC adapter. One of the 3 bottom pins of PJP1 not sure which one, maybe brown wire. (measure all 3 if unsure)

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, I tested all the pins on the connector and had 19.6v, 19.6v, 0v,0v,0v, 0.69v that is the centre pin of the charger voltage on the connector on the motherboard side.

[mcplslg123]

Re: HP 15-AC135NA Dead

Have you checked B+ resistor for short??

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, Where is the B+ resistor?

[shibu]

Re: HP 15-AC135NA Dead

maybe a little big resistor mentioned 010,or 020

[Andyd1970]

Re: HP 15-AC135NA Dead

Any Idea where this B+ resistor is.

[mcplslg123]

Re: HP 15-AC135NA Dead

just above the charger ic after dc in mosfet.

[lefos]

Re: HP 15-AC135NA Dead

Measuring the short on the caps how many ohms do you have?

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, The two caps (I suspect they are caps) I highlighted in picture, I get 1.7 ohms. I am still not sure where the B+ resistor is as I am not sure where the charge ic AND mosfet are.

[piernov]

Re: HP 15-AC135NA Dead

Green: B+ current sense resistor
Red: charger IC
Pink: DC-in MOSFETs

[Andyd1970]

Re: HP 15-AC135NA Dead

B+ resistor is giving 0.5 ohms and getting the beep on the meter

[mcplslg123]

Re: HP 15-AC135NA Dead

B+ resistor is giving 0.5 ohms and getting the beep on the meter

So my doubt is correct. Do you have a bench power supply ?? If yes then remove that resistor and inject 1-3volts on the shorted side of that resistor pads. Something will get hot.

[Andyd1970]

Re: HP 15-AC135NA Dead

Sorry just to clarify, I have put meter probe on ground and then other probe on each side of the B + resistor and I am getting a beep from the meter so I guess that implies a short to ground

[Andyd1970]

Re: HP 15-AC135NA Dead

If you look at the board in the orintation as in pic Piernov sent the short to ground is to the right hand side of that resisitor. I just removed the B + resistor and I have bloody lost it! hope I can replace with something else later I have just noticed a cap with a small bit of damage to the top of it so will remove that and see if short is there

[piernov]

Re: HP 15-AC135NA Dead

Yeah so that's on the system side, B+ rail. Lots of components there. If a capacitor looks bad it can indeed be suspected.
Also when injecting voltage always start at 1V and make sure CPU/GPU/PCH don't heat up before going higher to be on the safe side.

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi

I removed what I suspect is a cap, if you look at the pic you will see a couple of empty pads just to the right of where it says PUZ00, right in middle of image. I have tested the suspect cap and it is short circuit, so I guess thats was the fault? I have found the B+ resistor on my mat so shall I replace that? would anyone know the value of that short circuit? as I might be able to recover one from a faulty phone or ipad.
Thank you for your help.

[brew99]

Re: HP 15-AC135NA Dead

Before you replace anything, ensure that you no longer have a B+ rail short.

The B+ resistor is usually about 10mOhms, and is not easy to measure accurately with a typical DMM. The resistor is more than likely fine, but before you re-solder that back in, make sure the short on that B+ rail is now gone. There might have been more than one cap. that was shorted