HP laptop mobo no power

[fddizon]

hi,

my friend sent me a defective mobo with code DA0AX1MB6H1 REV: H
anyone with schematic, please post. i need to trace voltages.

adapter/charger is good. when adapter is inserted to dc jack, LED off on jack.

thanks

[fddizon]

Re: HP laptop mobo no power

There are 7 wires going to mobo that has the following voltages.

2 red wires has 20 volts, 2 black wires are grounds, the other wires has 0 volts. i am missing 19 volts from the adapter. I guess the dc jack is faulty.
can anyone confirm that DC jack can be repaired?
i see a soft plastic that is covering the wires at the back of the DC jack. slightly i can see the connections and parts inside. are these parts will be seen in schematic diagram?

[Pragmatiko]

Re: HP laptop mobo no power

Ummm I belive you have a corrupted BIOS

[Pragmatiko]

Re: HP laptop mobo no power

https://www.badcaps.net/forum/showthread.php?t=30001

[fddizon]

Re: HP laptop mobo no power

Ummm I belive you have a corrupted BIOS

Pragmatiko, does a bad bios can make the DC jack LED not to go on?
mine does not turn on even a bit when charger plugged in

[fddizon]

Re: HP laptop mobo no power

The user told me his adapter/charger is broken and they purchased this multiple output charger. maybe they mis use the voltage and polarity. no short is showing from the circuit. just no 19 volts from the adapter.

does the center pin voltage will go out from the DC in wires? no 19 volts even if i disconnect the dc connector from the mobo.
but checking directly from the plug center pin, 19 volts is present.

[fddizon]

Re: HP laptop mobo no power

made some test from a hp pavilion dm1 that uses the same dc jack. this laptop is working.
when charger is inserted to jack with battery, led lights white first then red, seems it is charging its battery. i remove the dc connector from mobo, and the LED turns off. i measured voltages giving 20v from red wires and 18 volts from green wire.

it seems that we are missing the pin voltage from the hp g42-478TU dc connector.
anyone who has the same model at hand to confirm voltages coming out from dc connector?

thanks

[fddizon]

Re: HP laptop mobo no power

i hope spidey can help me once again with the schematic...

thanks in advance

[spidey]

Re: HP laptop mobo no power

i have ax1, rev :1a

[fddizon]

Re: HP laptop mobo no power

thanks spidey... let me check if the same

[Pragmatiko]

Re: HP laptop mobo no power

made some test from a hp pavilion dm1 that uses the same dc jack. this laptop is working.
when charger is inserted to jack with battery, led lights white first then red, seems it is charging its battery. i remove the dc connector from mobo, and the LED turns off. i measured voltages giving 20v from red wires and 18 volts from green wire.

it seems that we are missing the pin voltage from the hp g42-478TU dc connector.
anyone who has the same model at hand to confirm voltages coming out from dc connector?

thanks

[fddizon]

Re: HP laptop mobo no power

pragmatiko,

those voltage are present... not in the mobo dcin connector

[fddizon]

Re: HP laptop mobo no power

spidey,

the schematic does not match my mobo.

please help... anyone who have this schematic?
code DA0AX1MB6H1 REV: H
hp g42-478TU

thanks in advance

[speedypro]

Re: HP laptop mobo no power

Pragmatiko, does a bad bios can make the DC jack LED not to go on?
mine does not turn on even a bit when charger plugged in

Talking from experience with HPs, I can say yes and no. If that issue comes into our workshop, I would target BIOS and GPU. GPU?????? YES! I have worked on a HP Pav that has no sign of life but 19v is present on the mobo. USB and all other SMD sockets were all ok. I did a reflow of the gpu and there was power. Weird I know but I never found time to "do the math" to know why.

Remove any bios chip from any laptop and Im sure you will see that same issue; a laptop with no sign of power. That is where troubleshooting steps come in.

Best of luck!

[whaldsz]

Re: HP laptop mobo no power

Try to replace the bios chip or reprogram it. Speedypro is right. I got the same issue with cq40 today. removed the bios, plugged in the adapter, no led lights. Reprogrammed it, soldered it, and there it is... Led lights!

[vpha]

Re: HP laptop mobo no power

Hi
can i have the bios .bin file for CQ40 (Intel)?