Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

[obes]

The AC adapter is good, it spits out 19.15V when plugged in (checked at the connector that goes from the jack to the motherboard, so the connector and its cable are good)

The fuses marked F6000 and F6100 are good too, 19V on both sides from ground, and continuity is ok across them.

CR2032 battery reads 3.10V

Unfortunately I am not that knowledgeable about electronics and that's about all I know to check. There are several pads exposed around the motherboard which I assume are for testing but I can't find a reference as to what readings are expected on them.

Symptoms are: when AC plugged in, not powering on at all (not even responding to button presses, not starting the fan up), and no lights at all (no AC or battery charging lights). Tried with and without the battery plugged in.

Any idea?

[JaroTech]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

Hi, to know which motherboard you have, what is the number of the U6000 chip?

[obes]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

Hi, to know which motherboard you have, what is the number of the U6000 chip?

I hope I have the right one, but the U6000 marking doesn't have any chip right next to it. This one is a bit to the left of the marking, and it's very small:
BQ725
TI 12K
A703

[JaroTech]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

Ok, you have the BQ24725 for the charging chip, if you can, measure all the voltages for the 20 pins of this chip. Like pin1 =?V, pin2 =?V and so on.

[obes]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

Ok, you have the BQ24725 for the charging chip, if you can, measure all the voltages for the 20 pins of this chip. Like pin1 =?V, pin2 =?V and so on.

Alright, here goes:

(measured without the battery plugged in, and with AC plugged in)
 1: 6.80V
 2: between 7.95 and 8.02V
 3: 6.00 to 6.80V, unstable
 4: 7.97V
 5: 0.03V

 6: 2.65V
 7: 0.00V
 8: went from 0.10V to 0.00V while measuring
 9: 0.04V
10: 0.00V

11: 1.07V
12: 1.05V
13: 1.05V
14: 0.00V
15: 0.00V

16: 6.03V
17: 5.86V
18: 1.05V
19: 1.05V
20: 18.87V

[piernov]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

Disconnect the battery while troubleshooting the motherboard.
Check for a short to ground on the B+ line. With the info we have, the easiest way is to give the resistance measurement between pin 1 (ACN) of the bq24725 and ground.
Also check the resistance between pin 1 (ACN) and pin 2 (ACP) of the bq24725. This is connected to the current sense resistor. It should be very close to 0ohm.

[obes]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

Disconnect the battery while troubleshooting the motherboard.
Check for a short to ground on the B+ line. With the info we have, the easiest way is to give the resistance measurement between pin 1 (ACN) of the bq24725 and ground.
Also check the resistance between pin 1 (ACN) and pin 2 (ACP) of the bq24725. This is connected to the current sense resistor. It should be very close to 0ohm.

With AC and Battery disconnected:

Resistance between 1 and ground isn't stable at first but eventually settles at 71.2k Ohms
Resistance between 1 and 2 is about 1.5 Ohm (if I can trust my cheap multimeter to be that accurate)

Not sure which pins are +, -, and ground on the battery connector so didn't measure that.

[obes]

Re: Toshiba C650M (PSC2EC-00M001) wont't power on or charge. How do I troubleshoot?

I appreciate your help, any thoughts on the latest measurements?

How can I tell if the voltages I got from the TI chip are within spec or not?