HP 15-AC135NA Dead

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, OK but I am not sure where the B + line goes? also do you think I should be able to get away with leaving that cap off? if not does anyone know its value, tolerance and voltage please.

[brew99]

Re: HP 15-AC135NA Dead

Use your DMM in diode mode and put the red lead on ground point somewhere, and the black lead on one side of the pad where you removed the B+ resistor. What is the Voltage reading? What about the other pad of the B+ resistor location (black lead)? What is it's voltage reading?

If you are reading something around 0.4-0.6V you don't have a short anymore. If either are 0.00V or so, then you still have a short on the B+ line.

If you have no short, you can probably leave the cap off, but I prefer to replace if I am going to use for long term.

[mcplslg123]

Re: HP 15-AC135NA Dead

No need to apply power and test voltage at this stage. Rather you should once again test both sides of B+ resistor in diode mode. If it no more shows short, put the B+ resistor back and apply voltage going with 1v at the beginning and then slowly increasing it. I assume you have a dc supply with you.

[mcplslg123]

Re: HP 15-AC135NA Dead

Hi, OK but I am not sure where the B + line goes? also do you think I should be able to get away with leaving that cap off? if not does anyone know its value, tolerance and voltage please.

It will hardly matter. Just replace it with similar looking cap from a scrap board.

[piernov]

Re: HP 15-AC135NA Dead

Except that if it's on B+ it'll have to be at least rated for 25V… Otherwise you'll get some nice fireworks.

[Andyd1970]

Re: HP 15-AC135NA Dead

Sorry for delay, I checked the B + rail both side in diode mode and got around 0.5v so replaced B + resistor and now get the red light, thank you all so much. But I want to replace the cap but have no idea on its value as there are no markings on it or near it and it is SC so cant check. Any ideas? or do you think it is OK to leave off?

[brew99]

Re: HP 15-AC135NA Dead

I don't think you ever mentioned the motherboard part number in the post? If you can find that, then maybe we can help you find a schematic or boardview, and look up that cap. value.

Otherwise you might just use your DMM (if it can measure capacitance), and measure the cap right beside the one that was shorted (they look similar), to give you a rough idea for a capacitance value. As Piernov pointed out, it is most likely atleast a 25V rating as it is on the B+ line

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, OK..

ABQ52 LA=C811P REV 1.0
MO: 39704880
SPS:815249-501
Date code:7J1630

Hope that is the correct info from motherboard

[Andyd1970]

Re: HP 15-AC135NA Dead

Hi, I have just used a PEAK Atlas ESR meter from a friend..

I get 165.8uf ESR 0.09 ohms.

Does that help ?

[brew99]

Re: HP 15-AC135NA Dead

I can't find that schematic or BV. Does it work now without the cap? If so, don't worry about it for now.

[Andyd1970]

Re: HP 15-AC135NA Dead

All seems to be working fine, thank you all.