lenovo, no EC_ON signal

[ktmmotocross]

hello. my friend bring me board with "two bad tranzistors". I check it and it looks like bad charging chip BQXXXX. So i jump second mossfet on adapter side to have B+ 19V. i have 19V on PJ401, 3.3V on pj404. But dont have EN1 /+3VALW_EN/ from SIO. Do u think SIO is bad?

[fester]

Re: lenovo, no EC_ON signal

you have PJ401 and PJ404 populated? according to schematic is not (@ sign),bevare of connecting both sides of this jumpers, "second mosfet" is which one?

[ktmmotocross]

Re: lenovo, no EC_ON signal

second mosfet is PQ302

that jumpers is from factory.

[fester]

Re: lenovo, no EC_ON signal

charging chip communicate over i2c with SIO so if is this chip faulty SIO is not switching ALW power lines imho must not to be bad.change this charging ic first

[piernov]

Re: lenovo, no EC_ON signal

First change charger IC and it should solve your issue, EC needs to communicate with it. Make sure you're using AC power and no battery.
If it still doesn't work try to flash the IT8586E.

[ktmmotocross]

Re: lenovo, no EC_ON signal

i replaced charger chip but nothing changed. still have no EN1 /+3VALW_EN/ from SIO


dont have programmer for it

[piernov]

Re: lenovo, no EC_ON signal

I cannot understand the EC's initialisation process, but I guess that EC_ON should be high as soon as VSTBY0 is available. So I would say replace EC.

[fester]

Re: lenovo, no EC_ON signal

Yesterday i had one board with the similar situation,i had power after first mosfet bud second was off..problem was in shorted ceramic capacitor in high side of +3ALW line..this can be also your problem,short somewhere after second mosfet -> over current sensing resistor flow big current -> sio switch it off via charging chip. try inject small voltage(maybe 1V) direct to all ALW power lines and watch the current

[ktmmotocross]

Re: lenovo, no EC_ON signal

maybe u have right. after changing BQxxxx i have ACOK and ACPRN. but afteer jumping second mosfet, the short come out

im going to inject to vin line

[ktmmotocross]

Re: lenovo, no EC_ON signal

ok, i replace the short in PQ312

but no change. i make some measures

dont have PACIN

[fester]

Re: lenovo, no EC_ON signal

inject direct to 3V alw line,if ok,then try 5V alw line,i dont understand so complex cirquit with all signals like this one :-) on my board i spend maybe 3 hours tracing and meassuring and i gave up because everythig was ok imho...
btw ACPRN != PACIN as it goes over PQ309B so you cannot have booth at one time

[ktmmotocross]

Re: lenovo, no EC_ON signal

so know anybody which signals must have, so second mosfet switch on
as it is P channel, i must have BATT_OUT or PACIN to have negative voltage on secong mosfet gate

[piernov]

Re: lenovo, no EC_ON signal

Check voltage on pin ACOK, VCC, SRN, ACDET, REGN of charger IC.
ACOK must be low on bq247x7 for PACIN to be high.

[khaahk]

Re: lenovo, no EC_ON signal

6V at acoff-1 is bad, where it is coming from?
it will bring the pacin_g to gnd and you will have 19V at P2-2

Adapter is smart and ok?
I believe ~380K to gnd from id pin was the value for lenovo.

[ktmmotocross]

Re: lenovo, no EC_ON signal

Check voltage on pin ACOK, VCC, SRN, ACDET, REGN of charger IC.
ACOK must be low on bq247x7 for PACIN to be high.

but acok is signal from BQxxx that AC is detected and is ok

[piernov]

Re: lenovo, no EC_ON signal

ACOK is active low on bq24737 (see datasheet for bq24707, it's pretty similar) so if you have a voltage on this pin, something is wrong. You should have 0V.
You can also check the bq24707 datasheet for the conditions which leads to ACOK activation (involving the pins I listed).

[ktmmotocross]

Re: lenovo, no EC_ON signal

maybe i have bad datasheet for BQ

[ktmmotocross]

Re: lenovo, no EC_ON signal

i can not find datasheet for 737.
from datasheet of 707 i must have SRN high like VCC, but i have 0,15V and no short to ground on that signal. acok is 6V and from datasheet it is fault.
Is my BQ bad? /it a new one/

i make some better measurement so chceck it out

[piernov]

Re: lenovo, no EC_ON signal

According to the datasheet, the conditions are as following:

• voltage on the ACDET pin is above 2.4 V
• voltage on the VCC pin is above UVLO
• voltage on the VCC pin is 245 mV above the voltage on the SRN pin

Voltage on the SRN pin has to be at least 245mV lower than VCC. There is no lower threshold, so I guess 0V is OK too. SRN is connected to the battery line so I think it is never around 19V.
Check the voltage on ACDET, and make sure VCC is around 19V. If they are ok and ACOK is still high, maybe the IC is bad and you can try putting a new one.