Hp 8460W No Power

[CraigR]

Hp 8470W with no signs of life. Not the power cord as I have tried several. Pulled motherboard and checked power at the back of the jack with cord plugged in and voltage massively fluctuates up and down over and over and never gets above 3 volts maybe. I used a thermo cam and found 1 mosfet that pulses and another that gets real hot (see pics) I replaced both of these with new and same thing. I checked sever caps for shorts and nothing. Any insight would be appreciated.

[mon2]

Re: Hp 8460W No Power

Title reads HP 8460W, post mentions HP 8470W. Which model is this laptop ? Any other markings on the logic board for identification?

[Stevedb]

Re: Hp 8460W No Power

You need to measure all coils to ground at 200 ohms. So that somebody can see what the problem is. Write values on hd picture. If you do not get reading just write OL. Does the same with power. For resistance remove ram, CPU , wifi module etc. For power is ram needed.

Good luck

[CraigR]

Re: Hp 8460W No Power

Title reads HP 8460W, post mentions HP 8470W. Which model is this laptop ? Any other markings on the logic board for identification?

It's 8470w I could not edit title.

[CraigR]

Re: Hp 8460W No Power

All coils test 200-300ohms I found a mosfet shorted, not sure if I did it or not but had to order new one from China so I will repost when it gets here and put in.

[mon2]

Re: Hp 8460W No Power

Can you post the part # for the mosfet?

Often the mosfet can be replaced with another. We did this recently using a TI mosfet with better specs to replace the original AON6414A.

[CraigR]

Re: Hp 8460W No Power

Ordered this am already so will just wait but thanks for the suggestion.