Lenovo N500 - No power

[rtstorm]

Re: Lenovo N500 - No power

when i remove PQ5 same thing happen, voltages still osctilates

[rtstorm]

Re: Lenovo N500 - No power

i try to remove PQ19 and now i have 0V on that rail that i have earlier oscilating voltages

[spleenharvester]

Re: Lenovo N500 - No power

That's pretty peculiar. B+ is connected to PU10, and since removing PL12 stops the oscillation, and since removing PQ5 does not stop the oscillation, that suggests that any component between PL12 and PQ5 could be bad. So PC39, PC38, PC37, PC36, PC150, PR17, PC13, PC8, PC1, maybe even PU1 itself.

Or whatever the hell is connected to CHG_B+.

Again, I could be wrong! I'm no professional at this. It might be worth checking PQ32 and PQ34

EDIT: If it did work on battery PQ32 and PQ34 would be okay, actually. Which would also mean B+ is fine and it's something charger-related (I suppose CHG_B+ could still be at fault)

[spleenharvester]

Re: Lenovo N500 - No power

Just took another look, this isn't making much sense to me. Presumably, voltage would be flowing through those components while on battery anyway? And if it was indeed working on battery, this suggests the problem is elsewhere?

[rtstorm]

Re: Lenovo N500 - No power

i found the problem, it was solder bridge on PQ19, now i have 17V on that rail, and 3V on BIOS

[rtstorm]

Re: Lenovo N500 - No power

uhh i will go crazy with this one, i have 16.9 and 17.10 oscilating voltage on that rail. Laptop still wont start

[whaldsz]

Re: Lenovo N500 - No power

there is a possible leaky capacitor or fet along the 19v rail. you should use your bench power supply to isolate it.

[khaahk]

Re: Lenovo N500 - No power

Such a small variation should not interfere with startup. The b+ rail can be from 19v to battery voltage. But it indicates that something is wrong. On pg 46, the oscillation is at pq38 drain only or source also? +5alw and +3v exist and are stable?

[rtstorm]

Re: Lenovo N500 - No power

this is crazy i check now and i have stable 14.8V on drain of PQ38. Source is 19V.

On PU10 3V output is 0V and 5v output is oscilating 0-4v

[rtstorm]

Re: Lenovo N500 - No power

ahh now again oscilating voltage at PQ38

[gorip]

Re: Lenovo N500 - No power

have you ever tried to clean up these area? . insect pee sometimes leave no trace