B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

[mon2]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

What are the voltage readings of pin # 4 (gate) on:

PQ301

PQ302

- check both with the adapter connected - no battery.

Also check and post the readings @

PQ301 - pins 1-2-3 (any of these pins is ok for the measurement)

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Both gates PQ301 and PQ302 are 19,5V.
PQ301 input: 20V, output 19,5V;
PQ302: input: 19,5V, output 0,8V.

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Waiting for any ideas :<
My idea was to try maybe trace the PGood status of PU301, but im not sure where and what to look for...

[mon2]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Both PQ301 & PQ302 are P-channel mosfets.

With P-channel mosfets, the GATE must be lower than the voltage being passed between source & drain. If you are measuring 19v @ the gate pin # 4, then the mosfet should be OFF.

PQ302 appears to be OFF and this is expected.

PQ301 appears to be full ON - incorrect for P-channel.

Confirm the voltages on PQ301 again - source; drain; gate.

Was this part replaced and soldered on in the same orientation ?

It appears to be leaking if source & drain are at the same voltage yet GATE = 19v.

Check with removing all power. Wait a minute to allow for discharge of the caps.

Meter in resistance mode - check the resistance across the pins like before:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post the readings.

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Picture with voltage measurements in attachment.
The second schematic screenshot shows the gate for PQ301. If I have 19,5V on gate there, then something attached to it should give 19,5V right? Either Green line, Yellow line, or from the mosfet itself (which shoudln't happen given the resistances from before right?)

[mon2]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

If I have 19,5V on gate there, then something attached to it should give 19,5V right?

No. This is a P-channel mosfet so the gate has to be sufficiently negative or lower than the voltage INPUT to enable the mosfet.

You have ~20 V as input and ~19v5 as the output with the gate @ 19v5 which is not low enough on the gate pin to turn on this mosfet.

Do you have another P-channel mosfet you can use to replace PQ301 ?

[mcplslg123]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

No. This is a P-channel mosfet so the gate has to be sufficiently negative or lower than the voltage INPUT to enable the mosfet.

You have ~20 V as input and ~19v5 as the output with the gate @ 19v5 which is not low enough on the gate pin to turn on this mosfet.

Do you have another P-channel mosfet you can use to replace PQ301 ?

This is happening perhaps as first dc in fet is working in diode mode due to improper biasing of gate voltage. The mosfet itself is unlikely to be bad.

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

So, what do You suggest mcplslg123 ?

[SMDFlea]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

This is happening perhaps as first dc in fet is working in diode mode due to improper biasing of gate voltage. The mosfet itself is unlikely to be bad.

Shouldnt PQ303 be bringing the PQ301 gate voltage down and to do that PQ304 should be switched on.The PQ301 gate voltage should be at least 5V lower ?

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

I've removed the PQ303 and measured its resistance:
Pin 1 - IN; 2 -GND; 3-OUT
1-2 95 KOhms no matter the polarisation
1-3 6,75 MOhms with red on 1; no reading opposite
2-3 6,75 MOhms with red on 2; no reasing opposite
In diode mode: no reading no matter which pin and which polarisation.
Quick google for schematic and added it in attachement.

[mcplslg123]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

So, what do You suggest mcplslg123 ?

Remove both PQ303 & PQ304 and power up. Check Readings on PQ301/PQ302 again. It wont harm you to apply power without PQ303/304 as they are just protection circuit.

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

After desoldering PQ303 and PQ304, small difference in voltage at the gates - 19,18V not 19,5V - screenshot in attachment.
So do You think the culprit could be the PU301?

[mon2]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Post the measurements for points # 1 & # 2 of the attached.

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

1: PQ305 pin 2 and 5 (the same): 0V; resistance to ground 10,9 kOhms
2: PR305 2nd leg: 0V; resistance to ground 57,3 kOhms

[mcplslg123]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Have you replaced BQ24737 so far?? Yes it could be faulty but there can be so many reasons. Is PQ310 not broken??PACIN is missing and this is needed to trigger voltage divider for PQ301 gate. When PQ305B,pin5 will be high, GND will reach pin3 and then PR302/304 will work as voltage divider. Since GND is missing on PR304,pin2 its not working as voltage divider. So search all traces related to PACIN and check them. BQ24737,ACOK aka ACPRN will be active low. Do you get 19V on pin20 and 6V on pin16 of PU301??

[SMDFlea]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Shouldnt PQ303 be bringing the PQ301 gate voltage down and to do that PQ304 should be switched on.The PQ301 gate voltage should be at least 5V lower ?

Have you replaced BQ24737 so far?? Yes it could be faulty but there can be so many reasons. Is PQ310 not broken??PACIN is missing and this is needed to trigger voltage divider for PQ301 gate. When PQ305B,pin5 will be high, GND will reach pin3 and then PR302/304 will work as voltage divider. Since GND is missing on PR304,pin2 its not working as voltage divider. So search all traces related to PACIN and check them. BQ24737,ACOK aka ACPRN will be active low. Do you get 19V on pin20 and 6V on pin16 of PU301??

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Have you replaced BQ24737 so far?? Yes it could be faulty

No, not yet. I could order it new, and try to replace it, but I would like to learn, how to know if its broken:-)

Is PQ310 not broken??

PQ310 Voltages:
pins 1-3: 0,8V (its the same voltage as PQ302 output)
pin 4: 3,5V
pins 5-8: 1,2V
No shorts

Do you get 19V on pin20 and 6V on pin16 of PU301??

PU301 pin 20: 19,5V
PU301 pin 16: 6V
So yes, those are the voltages present.

[mon2]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

PR305, pin #1 was requested.

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

PR305, pin #1 was requested.

2: PR305 2nd leg: 0V; resistance to ground 57,3 kOhms
1st leg is the same as PQ305 pin 2 and 5.

Or i changed them up, so 1 is 2 and 2 is 1 sorry

[ITworkshop]

Re: B+ Voltage rail; Lenovo Y510p VIQY1 NM-A032

Have you replaced BQ24737 so far?? Yes it could be faulty but there can be so many reasons.

So should I order and replace PU301 (BQ24737), or desolder it and try to measure on the board if its for sure its fault and nothing else?