pls help HP 250 G4 NO POWER .

[mo000]

Hi everyone
hp 250 g4 LA-C701P is dead
when i plug in the charger the power led is on but when i press the power button nothing happen

when i press the power button the ic PU2 (RT8243AZQW 3/5V) becomes hot ; i change it with new one but same problem
EC_ON , MAINPWON signal are exist and LDO3 AND LDO5 Exist too
VIN voltage exist
everything is ok and no short on output pins
but i don't know why the ic becomes hot .

[mo000]

Re: pls help HP 250 G4 NO POWER .

any ideas .

[qayyum786]

Re: pls help HP 250 G4 NO POWER .

Check boost capacitor and feedback rasistor

[mcplslg123]

Re: pls help HP 250 G4 NO POWER .

What is the voltage on pin 13 of PU2 when you turn it on?? Impedance on coil PL8/PL9 in diode mode?? Resistance in Ohms mode??

[mo000]

Re: pls help HP 250 G4 NO POWER .

What is the voltage on pin 13 of PU2 when you turn it on?? Impedance on coil PL8/PL9 in diode mode?? Resistance in Ohms mode??

pin13=3.3

PL9 1014ohms
but pl8 360ohms sometimes becomes 30ohms .

[mo000]

Re: pls help HP 250 G4 NO POWER .

Check boost capacitor and feedback rasistor

can you specific pls .

[mo000]

Re: pls help HP 250 G4 NO POWER .

someone help pls .

[mo000]

Re: pls help HP 250 G4 NO POWER .

i desolder the jumber PJP3 but same problem i think the whole problem in 5VALW side .

[mcplslg123]

Re: pls help HP 250 G4 NO POWER .

Remove jumper PJP2 also and check again whether PU2 is still getting hot. may be bad KBC.

[mo000]

Re: pls help HP 250 G4 NO POWER .

Remove jumper PJP2 also and check again whether PU2 is still getting hot. may be bad KBC.

I do but PU2 still getting hot .

[mcplslg123]

Re: pls help HP 250 G4 NO POWER .

Measure resistance on all pins of PU2 and voltage on each pin. Are you sure you soldered a new PU2 or pulled from scrap mb??

[Duranitron]

Re: pls help HP 250 G4 NO POWER .

Measure resistance on all pins of PU2 and voltage on each pin. Are you sure you soldered a new PU2 or pulled from scrap mb??

op said i change it with new one but same problem.

something is shorting pu2.. if you done desoldering the jpj2 jpj3. and still the ic overheat.. maybe its a bad ic batch... can you picture the pu2 for us.. tnx..

[mo000]

Re: pls help HP 250 G4 NO POWER .

Measure resistance on all pins of PU2 and voltage on each pin. Are you sure you soldered a new PU2 or pulled from scrap mb??

i pulled from working motherboard , i'm sure .

[mo000]

Re: pls help HP 250 G4 NO POWER .

op said i change it with new one but same problem.

something is shorting pu2.. if you done desoldering the jpj2 jpj3. and still the ic overheat.. maybe its a bad ic batch... can you picture the pu2 for us.. tnx..

yes i desolder jpj2 and jpj3 and i also desolder pl8 but pu2 still overheating without output .

[mo000]

Re: pls help HP 250 G4 NO POWER .

unfortunately the client take back his laptop , thnx mcplslg123 and duration for help .

[mcplslg123]

Re: pls help HP 250 G4 NO POWER .

i pulled from working motherboard , i'm sure .

I'll still bat for this ic being bad or badly soldered. However, its useless now since its no more with you.