Acer 5740 dead no power no led indication

[Naitikpatel]

Dear all,

plz help me recently i had acer 5740 (i3) wriston JV50-CP which was not power on.

At TPS51123 i got 5v & 3V @ pin 8 &17
Battery connector i had 3.3 v
@ U16 ec bios pin no. 8 - 3.3v
@ U56 system bios no voltage at any pin

Plz suggest me what should i do next...sorry for my bad english.

[piernov]

Re: Acer 5740 dead no power no led indication

Flash EC ROM.

[String2016]

Re: Acer 5740 dead no power no led indication

try to flash the ec first try with this attachment

[Naitikpatel]

Re: Acer 5740 dead no power no led indication

Thanks Guyz for reply .
i try to flash EC and i have CH341a USB Programmer black edition but when ever i try to write bios it will shows the error "chip with the contents are in disagreement " how resolve it plz suggest.

[RethoricalCheese]

Re: Acer 5740 dead no power no led indication

Did you delete chip content before flashing?

[Naitikpatel]

Re: Acer 5740 dead no power no led indication

yes ,i erase but this to not work

[RethoricalCheese]

Re: Acer 5740 dead no power no led indication

Try to read the chip and see what you get.

Probably just a bad connection or maybe a faulty chip.

[Naitikpatel]

Re: Acer 5740 dead no power no led indication

Yes i can read data ,is there any dump comparision method to compare with new dump
And second thing this ic is not available india so can i use alternate ic in place of this

[Naitikpatel]

Re: Acer 5740 dead no power no led indication

One more thing ,is there any id or serial no i write in dump to flash ic

[robgerr]

Re: Acer 5740 dead no power no led indication

try to clean adapter pin on the prorammer with isoprphilic alcohol

[BlueMidnight]

Re: Acer 5740 dead no power no led indication

Sometimes it's easy to get too far ahead of yourself. You want to make sure that you follow troubleshooting steps slowly and carefully, without skipping the basics.

3V/5V chips like the TPS51123 have 4 main outputs:

1. 3V linear regulator
2. 5V linear regulator
3. 3V switching/buck regulator
4. 5V switching/buck regulator

The EC BIOS is powered from the 3V linear regulator, so we know that is working. But the system BIOS is powered from the 3V switching regulator, and you couldn't find that voltage.

So, check the main switching/buck outputs next. Make sure you are getting 3V on pin 11 and 5V on pin 20 of the TPS51123 (U72). You can also measure those voltages at the coils/inductors L33 and L34 (it's easier that way). It certainly sounds like the 3V rail isn't working, but it's still a good idea to measure it at the source.

If you don't see one/both of those voltages, then check pin 18. This is the pin that tells the switching regulators to turn on.

If pin 18 is 0V, then we can start to suspect a problem with the EC. However, if pin 18 is 3V, then the next step is to check for a short circuit on the switching outputs.

To check for shorts, disconnect the AC adapter and battery. Then, use your multimeter in "diode mode", and place the red lead on ground and the black lead on each power rail (pins 11 and 20). If it shows less than about 0.1V, that rail definitely has a short circuit that you need to find.