Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VCPU

[u666sa]

Help fellow newb out! Fix his old salave netbook and learn fixing stuff in process.
ISL6237 had coffee damage, cleaned it with benzine. VIN is present, there is no 3VCPU and no 5VCPU. What do I replace? ISL6237 or PQ51, PQ52, PQ50, PQ55?
(isl6237 is two months away from china, no local availability)
What will be the most likely culprit here?

full size - https://ibb.co/6s0Q7rW


Attached boardview + schematics

[Techtiger]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

What voltage’s do you get on pin 1 3 4 5 7

[piernov]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

Measure resistance to ground on +3VPCU and +5VPCU.
Measure voltage on enable signals and LDO outputs.

[u666sa]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

pin1 --> 3.57V
pin3 --> 3.57V
pin4 --> 4.35V
pin5 --> ~60.0mV
note pin5 goes to PR98, on the other side of PR98 REFIN2, which is 3.57V
THERE IS NO PR98 on the board, there is place for it, there are pads for it, but PR98 is absent
it does not look like there was ever something on those pads, they look factory
Put jumper??



pin7 --> -0.00mV
note pin5 to ground resistance 0.8 Ohm


////////////////////////////////////////////////////////////////

Resistance -->

LDO to 3VPCU (measured PC148 to PL14) --> 1.2 Ohm
LDO to 5VPCU (measured PC148 to PL13) --> 8.6 kOhm
PC148 (pin7 LDO) to ground --> 0 Ohm, short (took off and checked PC148, it's normal)


Full size -- https://ibb.co/RS3RxQP

[u666sa]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

Measure voltage on .... LDO outputs.

+3VPCU to ground = 0.5 Ohm
+5VPCU to ground = 9.01 kOhm

EN1, EN2 pin14, pin27 3V5V_EN --> -0.00V


About measuring voltage on LDO output, I'm a newb, I would need help with this one, where exactly? If LDO itself, pin7, then it's -0.00V, that thing is shorted to ground.

Which pins are LDO output?

[mcplslg123]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

Your chip is bad. Remove the chip,clean the pad,pins and then check resistance on pin7

[u666sa]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

I replaced PU7.. There was no original in the store, so I used analog DS8206A -- datasheet https://cdn.badcaps-static.com/pdfs/...270d18a4ca.pdf

I checked resistances, all seemed normal, gave it power and magic smoke come from U7
which is IT8502E., multicontroller.





I took U7 off and measured voltages and resistances

LDO --> 3VPCU == 170.5 kOhm
LDO --> 5VPCU == 207 kOhm

3VPCU --> GROUND == 72.5 Ohm
5VPCU --> GROUND == 8.32 kOhm

3VPCU == 0 V
5VPCU == 0 V

VIN is not coming to PU7, but without U7 it shouldn't be coming there, correct?

Now I have an IT8502E from a donor, but before I stick in there, perhaps I should check some stuff in order to prevent more magic smoke?

What to check?

[mcplslg123]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

3VPCU --> GROUND == 72.5 Ohm- Shorted line.

[u666sa]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

3VPCU --> GROUND == 72.5 Ohm- Shorted line.

I've taken down PL14 on 3VPCU circuit, so that IS6237 won't interfear.
I've attached a test point wire to pin2 of PL4 pad, OUT2, this is from where 3VPCU should come out.


Then I took off everything on that line that got hot.

That is
in the order that I took them off
keep in mind that U7
IT8502E multicontroller was already off at this point

U9
W25X80AVSSIG




D11




PU4
ISL88731A
battery charger
and then PQ39 and PQ37 next to it





Resistance of 3VPCU to GROUND is now 27.9 kOhm


Does this mean, those components are bad and should I replace them, it might work again?

[Sephir0th]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

@u666sa

I believe You decided to Remove all of them, because of the temperature they Had reached?

Really, i don't think all of them are Bad. You should have measure the Résistance to GND of +3VPCU after the removal of each component to confirm which one(s) is/are Short to GND.

After replacing the faulty IC(s) you Always should Check Resistance to GND around the IC before Power in the Board to prevent situations Like this.

[mcplslg123]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

@u666sa

I believe You decided to Remove all of them, because of the temperature they Had reached?

Really, i don't think all of them are Bad. You should have measure the Résistance to GND of +3VPCU after the removal of each component to confirm which one(s) is/are Short to GND.

After replacing the faulty IC(s) you Always should Check Resistance to GND around the IC before Power in the Board to prevent situations Like this.

Hey man,
That case is almost 2 years old

[Sephir0th]

Re: Lenovo IdeaPad S10-3 (Quanta FL5 DAFL5CMB6C) - water on ISL6237, no 3VCPU, no 5VC

Oooops...