acer aspire 4738z bios need main and ec

[kiraro]

Re: acer aspire 4738z bios need main and ec

Check LM393 ,or replace it with a good one .

[Romulo]

Re: acer aspire 4738z bios need main and ec

Kiraro i cannot find the LM393 in the board.could you show me where is located?i dont have schematic for this.

[kiraro]

Re: acer aspire 4738z bios need main and ec

i think this is the schematic of the model or approximately :
see page 44 thermal protection (LM393) who generate system shutdown (SYS_SHDN# )

[Romulo]

Re: acer aspire 4738z bios need main and ec

Thanks for the schematic kiraro i will try to find and check ill update soon

[Romulo]

Re: acer aspire 4738z bios need main and ec

I checked the schematic and measured the pu10 LM393 voltage on pin 7 is 0.25v so i changed with the same chip LM393 from the scrapboard when i measured pin 7 there is now 2.4v but in the schematic output pin 7 of LM393 should be 3.3v. when i test the laptop still the same issue it turns on normal fan spins but after a second shuts off but led light is still present. any advise what should be next to check and replace? please help me

[kiraro]

Re: acer aspire 4738z bios need main and ec

Mesure Pin1 of lm393 and (pin2 and 3) of pq39, Try also change U13 thermal sensor .see if there is another lm393 defective also.

[kiraro]

Re: acer aspire 4738z bios need main and ec

After checking above try to Check System PWR_OK on U24 sys_pwrok if it is missing that indicate you are missing some voltages on mobo,that may help to know if all the voltages are OK or not .

[Romulo]

Re: acer aspire 4738z bios need main and ec

I measured pin 1 of lm393 0.25v and measured pin 2 and 3 of pq39 0.34v i did not found any lm393 only 1 at pu10 ive noticed when i press power on and fan spinning i measured pin 7 of lm393 its 2.4v but when fan stops it drops to 0.40volts there is no voltage also on U24

[kiraro]

Re: acer aspire 4738z bios need main and ec

No voltage on u24 mean there is a missing voltage on mobo verify all voltage on coil(CPU core ,VGA core ,....),find your missing voltages according with schematic,check pu9 vo also.

[sedinfo33]

Re: acer aspire 4738z bios need main and ec

plz I need bios bin file
hp compaq presario cq58-120sk

[Romulo]

Re: acer aspire 4738z bios need main and ec

Ill measured all the coil voltage near cpu and gpu core there is no voltage on the coil.only coil PL13 and PL14 have voltage of 3.3 and 5volts.i cannot find pu9 on the board.any advise please

[Romulo]

Re: acer aspire 4738z bios need main and ec

When i test again the laptop turns on seconds shuts off but this time no led lights present

[kiraro]

Re: acer aspire 4738z bios need main and ec

Page 37,check if there ils a short on +3V_S5,+5V_S5,+5V,+3V ,if there is a short on s5 this is may be why she drop down after few seconds.if you don't find short make measure when turn on that +3v_s5 and +5v_s5 goes out without problem if not check S5D signal ,I have a problem before that +5s5 become 1,8v no short but broken resistance on s5 gate signal.

[Romulo]

Re: acer aspire 4738z bios need main and ec

I checked +3V_S5 at PQ17 plugged in charger there is no 3v also the same at +5V_S5 at PQ18 there is no 5v but when pressing power button fan spin and stops ill measured again voltage present 3v and 4.7 on PQ18.on +3v on PQ58 pin 6 1.7v and pin2 0v but pressing power button pin 2 and 6 have 3.3v the same on +5v on PQ56 pin 2 0V and pin 6 5v but pressing power button both pins have 5volts the same in PQ57 pin 1 and 2 novoltage pin 3have 3v but pressing power button still the same any advise please

[Romulo]

Re: acer aspire 4738z bios need main and ec

Anyone please help

[Romulo]

Re: acer aspire 4738z bios need main and ec

Any help and advise on this please

[Romulo]

Re: acer aspire 4738z bios need main and ec

Any advise and help on this please

[Romulo]

Re: acer aspire 4738z bios need main and ec

any help on this please i still cannot find the culprit on the board

[Romulo]

Re: acer aspire 4738z bios need main and ec

Anyhelp please laptop fan still turns on then a minute shuts off but led lights steady

[mannypokwang]

Re: acer aspire 4738z bios need main and ec

Bro. Yung lm393 pin5&6 short ba?