HP 255 G2 - No Video

[b171331]

Hi.

I got HP 255 G2, Board is osamu2-dis_kb_hpc mv_mb_v1 , HP Bios ID is 02191.

When i start the laptop current is 350 mA, after 3 seconds drops to 220 mA and stays there. No image on screen. Board looks clean, no water damage.

I replaced ram and flashed bios (used bios that ala_borbe
aka Donald uploaded here) , nothing changed.

Any help in diagnosing this would be appreciated.

Thanks

[fester]

Re: HP 255 G2 - No Video

check run voltages on coils,maybe some burned fet,coil or voltage regulator

[b171331]

Re: HP 255 G2 - No Video

Got voltages on all coils, 16,4v on battery coil, 0,78v and 0,89 on cpu coils.
Other coils on board 3,35v , 5,15v , 1,52v , 0,95v , 1,79v

I don't have schematic to see correct voltages.

[fester]

Re: HP 255 G2 - No Video

can you turn it on and off with power button or it turns on automaticaly after connecting power?

[b171331]

Re: HP 255 G2 - No Video

On and off with power button.

If i leave it on, cpu gets hot,fan start to spin.

[fester]

Re: HP 255 G2 - No Video

first,try it with external monitor,if still no picture then is problem in graphic chip.

[b171331]

Re: HP 255 G2 - No Video

No video on external monitor.
Only one chip on board, AMD APU EM2100ICJ23HM.

[fester]

Re: HP 255 G2 - No Video

have you tried it with disconected internal lcd?without schematics you cannot do much more..looking at every part under microscope and measuring every capacitor is lost of time in this case.

[Udemzy]

Re: HP 255 G2 - No Video

You can't do much, I'll suggest you do a reboil on the vga chip.

[f-bone]

Re: HP 255 G2 - No Video

I replaced the CPU on the same motherboard (BIOS rewritten etc) - all voltages present, still no image. I see that the LVDS connector is missing 3.3V coming UB3 mosfet (other side near FAN connector). Any fresh ideas?

[hispeck]

Re: HP 255 G2 - No Video

Hello Fester, i have same laptop, mine will turn on fan will move and stop then start again the second time but this time very fast, no display i cant even turn it off

[tonix]

Re: HP 255 G2 - No Video

try changing the gpu it must be the problem