Acer 5740 no power

[vickey_vip]

I have an Acer Aspire 5740g with no power - no lights . Adapter is tested ok , motherboard is getting power 19V from power jack . I've found mosfets getting 19V and U72 (tps51123) pin no 8 getting 1.5 volt instant of 3.3 (if I am not wrong) pin no 17 out 5 volt. I replaced 51123 but still same problem also 51123 get heated Any help please where to look ?

Mb part no is 09285-1m
48.4GD01.01M

[vickey_vip]

Re: Acer 5740 no power

anyone can give solution for this is there

[mielta]

Re: Acer 5740 no power

Hi
Often you must reprogramm the EC Bios for this model

[ktmmotocross]

Re: Acer 5740 no power

short on 3.3V line?

[vickey_vip]

Re: Acer 5740 no power

short on 3.3V line?

may be but no mosfet, transitor and capacitor short i check all are ok can ec bios programming solve this issue ?

[charafmak77]

Re: Acer 5740 no power

I have a malfunction I did not find the solution in a laptop (acer 48-4gd01-01m) I checked the circuit (TPS51125) I found 3.3 volts and 5 volts on the pin 8 and 17 are present but the main efforts 3.3 volts and 5 volts on the coils do not exist, I changed the Ic TPS51125 but to no avail after that I downloaded Flash files bios and changed (IO) but the same problem remained, knowing that I found this holiday is repeated in the same device
I ask the brothers if you can tell us the solution

[catami61]

Re: Acer 5740 no power

I have de same problem !! ¿someone who solved it?

[Techtiger]

Re: Acer 5740 no power

I have de same problem !! ¿someone who solved it?

Give us more details about the MB , what voltages you get in the TPS 51125 ?with the pin configuration

[catami61]

Re: Acer 5740 no power

OK, I'm working now, when go home I get the voltages. Thanks

[catami61]

Re: Acer 5740 no power

The voltages
1 -> 0v (ENTRIP1)
3 -> 2v (VREF)
4 -> 2v (TONSEL)
6 -> 0v (ENTRIP2)
8 -> 3.3v (VREG3)
11 -> 0v (LL2)
13 -> 1v (EN)
16 -> 18.96v
17 -> 4.99v (VREG5)
20 -> 0v (LL1)
23 -> 0v (PGOOD)

MOD Edit: Link to Schematics - https://www.badcaps.net/forum/showthread.php?t=122279
Reminder, rules and organization of this section https://www.badcaps.net/forum/showthread.php?t=117483

[Techtiger]

Re: Acer 5740 no power

The voltages
1 -> 0v (ENTRIP1)
3 -> 2v (VREF)
4 -> 2v (TONSEL)
6 -> 0v (ENTRIP2)
8 -> 3.3v (VREG3)
11 -> 0v (LL2)
13 -> 1v (EN)
16 -> 18.96v
17 -> 4.99v (VREG5)
20 -> 0v (LL1)
23 -> 0v (PGOOD)

MOD Edit: Link to Schematics - https://www.badcaps.net/forum/showthread.php?t=122279
Reminder, rules and organization of this section https://www.badcaps.net/forum/showthread.php?t=117483

S5 Enable Signal missing now you have to do some reverse engineering trace the signal back to SIO chip pin 102 what is the voltage you get in the pin this is the key to turn on always voltage what voltages you get Q20 all pins Q21 all pins ?

[catami61]

Re: Acer 5740 no power

S5 Enable Signal missing now you have to do some reverse engineering trace the signal back to SIO chip pin 102 what is the voltage you get in the pin this is the key to turn on always voltage what voltages you get Q20 all pins Q21 all pins ?

pin 102 0v

q20
1-> 0v
2-> 0v
3-> 0v
4-> 0v
5-> 4.7v
6-> 4.7v

q21
1-> 0v
2-> 0v
3-> 0v
4-> 0v
5-> 4.93v
6-> 4.93v

[Techtiger]

Re: Acer 5740 no power

pin 102 0v

q20
1-> 0v
2-> 0v
3-> 0v
4-> 0v
5-> 4.7v
6-> 4.7v

q21
1-> 0v
2-> 0v
3-> 0v
4-> 0v
5-> 4.93v
6-> 4.93v

S5 ON is not Enabling do you know how to find out the Basic requirements of SIO ? VCC Etc!

[catami61]

Re: Acer 5740 no power

S5 ON is not Enabling do you know how to find out the Basic requirements of SIO ? VCC Etc!

No, I'm new and I'm learning

[Techtiger]

Re: Acer 5740 no power

SIO Page 30 pin VCC 22 33 125 111 96 9 Any of these pins getting 3D3V AUX S5 (VREG3 )
Question for newbie from where this voltage come from ?
AVCC pin 67 ?
ECRST pin 37 ?
AD ID pin 63?
AC IN pin 89?
Resistance to ground without power pin 102 on diode mood?
Page 31 U50 pin 8 voltage?

[Techtiger]

Re: Acer 5740 no power

U12
ACOK pin 13 ?
VICM pin8 ?
Voltage

U3
Pin 8 and 1 voltage?

[catami61]

Re: Acer 5740 no power

U12
ACOK pin 13 ?
VICM pin8 ?
Voltage

U3
Pin 8 and 1 voltage?

I've a problem !!, I've accidentally made a short and damaged the BQ, I've requested a replacement, when I have it we will return to the topic, I'm sorry!!!

[Techtiger]

Re: Acer 5740 no power

No worries this is how we learn Even I did this mistakes at the beginning
Next time be careful , for the multimeter probe Connect wire connector to the front of the probe 1st screw probe 2 screw Swing needle so you can test pin point any pin IC look the pic

[mcplslg123]

Re: Acer 5740 no power

There are needle sharp probes available in plenty for multimeter.

[catami61]

Re: Acer 5740 no power

No worries this is how we learn Even I did this mistakes at the beginning
Next time be careful , for the multimeter probe Connect wire connector to the front of the probe 1st screw probe 2 screw Swing needle so you can test pin point any pin IC look the pic

Thanks !!!