Compaq cq40 no power issue 3v5v

[sasser]

hye all i got 1 compaq cq42-627tu. intel board. LA-410P. check 3v&5v not present. ene chip also no volt. anyone had face with this issue?
19v is present

C482 no volt R384 r740 c475 c474 this area no volt. are that means southbrigde culprit?

[opamp]

Re: Compaq cq40 no power issue 3v5v

Do you have voltage on PL302 and PL303? if not troubleshoot PU301

[sasser]

Re: Compaq cq40 no power issue 3v5v

thanks opamp to response. pl303 and pl302 no power. its that tu301 TPS51125 ?

[aanan]

Re: Compaq cq40 no power issue 3v5v

thanks opamp to response. pl303 and pl302 no power. its that tu301 TPS51125 ?

check voltage on TPS51125 pin no16.

[sasser]

Re: Compaq cq40 no power issue 3v5v

im not find any TPS51125 here only TPS51124. pin no 16 no volt.

[sasser]

Re: Compaq cq40 no power issue 3v5v

ENE KB926qf already change. also no 3v&5V

[opamp]

Re: Compaq cq40 no power issue 3v5v

3v and 5v comes out of TPS51124. So that means it has to be operational before you get voltage on ENE KB926qf. Change TPS51124

[ktmmotocross]

Re: Compaq cq40 no power issue 3v5v

it comes from TPS51125RGER_QFN24_4X4

from your TPS51124 is switched rails 1,5V/1,8v

[sasser]

Re: Compaq cq40 no power issue 3v5v

opamp thanks for your response. im try to change today. ktmmotocross i didnt find TPS51125RGER_QFN24_4X4 i only found TPS51124.

[sasser]

Re: Compaq cq40 no power issue 3v5v

for all if i change TPS51124 but no volt on vin at pin 16 no point right. i need to trace the 5v&3v before come into TPS51124. from schematic what i must check again?
bios chip also no volt.

[alihomee]

Re: Compaq cq40 no power issue 3v5v

tps 51125 is responsible for 3v and 5v try replacing it with a good one

[whaldsz]

Re: Compaq cq40 no power issue 3v5v

for all if i change TPS51124 but no volt on vin at pin 16 no point right. i need to trace the 5v&3v before come into TPS51124. from schematic what i must check again?
bios chip also no volt.

There's no point in checking further if pin 16 don't have a proper voltage. you must check the charger circuit.

Measure the pin voltages of BQ24740 and post back. You may also want to perform some resistance test or check for overheating components specially capacitors along the B++ rail.

Also the voltages of PQ100 and 101.

[sasser]

Re: Compaq cq40 no power issue 3v5v

thanks whaldsz i see BQ24740VREF got acin from b+ rail. i will post the result . PC109 PQ101 PQ103 should have some volt.

[sasser]

Re: Compaq cq40 no power issue 3v5v

i got zero volt on pin acin BQ24740VREF then trace up to PR102 no volt also. then i go to PQ103 pin 1-4 all i got 19v but 6-7 00.023 ~zero . are this mosfet culprit but i already changed with another fet ? then i try to trace PQ104 there have 19v then pc106 19v and pr106 19v .

[sasser]

Re: Compaq cq40 no power issue 3v5v

is see now where pu301 is not use TPS51125 but i dont know what code. but measure vin on that ic still no volt. PC312 also no volt

[vvacl]

Re: Compaq cq40 no power issue 3v5v

TPS51125 can be replaced by RT8205 (or CJ=xx or UP6182)
Check PU301:
pin 16 : 18.5v
pin 3: 2v
pin 8: 3v3
pin 17: 5v
if all were ok, reflash bios first -> then check wherether pin 102 of KB926 had 3v3?

[sasser]

Re: Compaq cq40 no power issue 3v5v

TPS51125 can be replaced by RT8205 (or CJ=xx or UP6182)
Check PU301:
pin 16 : 18.5v
pin 3: 2v
pin 8: 3v3
pin 17: 5v
if all were ok, reflash bios first -> then check wherether pin 102 of KB926 had 3v3?

yes correct vvacl but no volt on pin 16.

[whaldsz]

Re: Compaq cq40 no power issue 3v5v

yes correct vvacl but no volt on pin 16.

Post the voltages of pins 5,6 and 7 of PU102B. We need to know if PACIN is high.

[sasser]

Re: Compaq cq40 no power issue 3v5v

Post the voltages of pins 5,6 and 7 of PU102B. We need to know if PACIN is high.

only seen PU102 didnt find PU102B but in schematic hav PU102B is that wrong shcema? but i found PU102 below the measure result

pin 1 0v
pin 2 1.23v
pin 3 1.34v
pin 4 0v
pin 5 18.74v
pin 6 3.22v
pin 7 1.22v
pin 8 1.80v

[aanan]

Re: Compaq cq40 no power issue 3v5v

1] check pu101 pin no3, 19 v

2] pu101 pin no 11, 3 v

3] pu301 pin no16 ,19v

4] check B++ on 19v

post result.