Lenovo Y50-70 PQ301 overheating

[costivl]

Hello,

First of all please excuse my bad english as it is not my native language.

Two days ago when i was working on my laptop i felt that the left side of the keyboard is very hot and after 1-2 minutes i felt a smell of burnt plastic, i turned off the laptop, then i opened it inside and i found out that the power jack that connects to the motherboard was melting, i ordered the cord and replaced it, i was trying to find out the cause for that overheating and i just learned that the mosfet PQ301 is causing the overheating. Just to mention my laptop works perfect on battery without overheating. If i connect the charger PQ301 starts heating very fast, if i disconnect the battery and connect the charger PQ301 is cold, if i turn on the laptop with the battery disconnected PQ301 starts heating very fast and the laptop powers up, but if i dont turn it off it will melt the power jack again and maybe will damage the motherboard too.



I suspect that something is in short after the PQ301 or PQ301 is faulty, can you please let me know what i should check? I own a multimeter so i can check some of the electronic pieces. Thank you.

[peste]

Re: Lenovo Y50-70 PQ301 overheating

you have the diagram here, remove the PR302, remove the battery, turn on the laptop and see if anything is still hot (pg47).

https://www.laboneinside.com/lenovo-...matic-diagram/

[costivl]

Re: Lenovo Y50-70 PQ301 overheating

I removed PR302 and now PQ301 it is cold, what to check next? Or PQ302 is the cause?

[peste]

Re: Lenovo Y50-70 PQ301 overheating

I removed PR302 and now PQ301 it is cold, what to check next? Or PQ302 is the cause?

measures the voltage at point P3. (pg47).

[costivl]

Re: Lenovo Y50-70 PQ301 overheating

PQ302: voltage on P3 (pin 5-8) is 0.78V, the voltage on pin 4 is 9.80V and the pins 1,2,3 shows 1, PQ302 is removed from board!

PQ301: voltage on pin 4 of is 9.80V all other pins shows 1, PQ301 is not removed from board.

[Ikung]

Re: Lenovo Y50-70 PQ301 overheating

PQ302: voltage on P3 (pin 5-8) is 0.78V, the voltage on pin 4 is 9.80V and the pins 1,2,3 shows 1, PQ302 is removed from board!

PQ301: voltage on pin 4 of is 9.80V all other pins shows 1, PQ301 is not removed from board.

What voltage do you get from your adapter (without connecting to motherboard)?

[costivl]

Re: Lenovo Y50-70 PQ301 overheating

I needed to replace the battery on my multimeter as it was discharged. And i did the measurements again, here are the results?

I get 20,5V on adapter without being connected.

With PR302 removed from motherboard i read 20V on P2 and 20V on P3 also 20,5V on VIN, PF101 voltage on both pins is 20,5V

[Ikung]

Re: Lenovo Y50-70 PQ301 overheating

I get 20,5V on adapter without being connected.

With PR302 removed from motherboard i read 20V on P2 and 20V on P3 also 20,5V on VIN, PF101 voltage on both pins is 20,5V

That's means both MOSFETs (PQ301 and PQ302) are OK. Maybe the problem is on B+ lines. You should check for short on this area.

[costivl]

Re: Lenovo Y50-70 PQ301 overheating

I have no resistence between G-S and G-D on PQ303

I just found out that PU301 is damaged, there is a little hole on it so i need to replace it, can you tell me what can be the cause of this, what i should check on the board? There must be a short on something if PU301 got damaged.

[costivl]

Re: Lenovo Y50-70 PQ301 overheating

Problem was PQ312, it was on short between D-S, i replaced the mosfer and laptop works perfect now!

[Ictus]

Re: Lenovo Y50-70 PQ301 overheating

Hello may i ask where can i buy PQ312 mosfet?

[classicandy]

Re: Lenovo Y50-70 PQ301 overheating

Hello may i ask where can i buy PQ312 mosfet?

You can order online from China through AliExpress......

But that is unnecessary. If you need it urgently, you can get from other dead motherboards having similar MOSFETs. Just take note of the number written on the MOSFET. Once it ends with an EVEN number, u can use it to replace PQ312. Also check if it is okay and there are no shorts between the Gates and the Source or Drain.

PQ312 is AON7752. You can replace it with AON7408, AON7506, E070BN, etc...

PQ312 is a N-channel MOSFET and the ones I've listed are N-channels too and should work just fine

[mikay786]

Re: Lenovo Y50-70 PQ301 overheating

not sure if better to bump this thread or start another but having a similar issue with above board.

First found a shorted capacitor which i dealt with. Board is no longer reporting short when injecting voltage.

Still no power so when checking under thermal cam noticed PU301 was getting really hot 80+ c (BQ737 battery charge controller)

Removed from board, plugged in charger and checked PQ312 & PQ310 seem fine getting 20v and no shorts

Could it simply be BQ737 is bad? or has something caused it to go bad?

Also should laptop turn on without that chip?

[mon2]

Re: Lenovo Y50-70 PQ301 overheating

Replace the BQ737. They do go bad.

If it is heating up as you have observed, it is worth the replacement.

No the logic board cannot boot without this component.

The same component is linked to the first 2 mosfets (ACFET & RBFET) - see the detailed thread above from @Piernov. The charger IC boosts the input DCIN voltage to drive the gate of each mosfet so that they may turn on under specific conditions. Same charger is required to properly drive the mosfets to charge the battery.

[mikay786]

Re: Lenovo Y50-70 PQ301 overheating

Replace the BQ737. They do go bad.

If it is heating up as you have observed, it is worth the replacement.

No the logic board cannot boot without this component.

The same component is linked to the first 2 mosfets (ACFET & RBFET) - see the detailed thread above from @Piernov. The charger IC boosts the input DCIN voltage to drive the gate of each mosfet so that they may turn on under specific conditions. Same charger is required to properly drive the mosfets to charge the battery.

Thanks on order

[mikay786]

Re: Lenovo Y50-70 PQ301 overheating

replaced the chip and now laptop power button is lighting up so some success, and no heat spot.

unfortunately knocked and lost a capacitor / resister off pin 6, could someone please help identify component? have the schematics but cant really read it

https://www.laboneinside.com/lenovo-...matic-diagram/

[mon2]

Re: Lenovo Y50-70 PQ301 overheating

The body color of the part is yellow / mustard color. That is the hint that the part is a capacitor. Resistors are often black in body color.

You have lost PC312 = 0.01uf, 0402 SMD size, rated at 25 volts. The part is not super critical but is creating a small time delay. You should be fine to use as is till the part arrives to finish up the repair.

This part is ceramic and is non-polarized. You can solder in either direction.

This is a very low cost part and can be sourced from almost any donor board or from Digikey, Mouser, Arrow, AliExpress.

[mikay786]

Re: Lenovo Y50-70 PQ301 overheating

The body color of the part is yellow / mustard color. That is the hint that the part is a capacitor. Resistors are often black in body color.

You have lost PC312 = 0.01uf, 0402 SMD size, rated at 25 volts. The part is not super critical but is creating a small time delay. You should be fine to use as is till the part arrives to finish up the repair.

This part is ceramic and is non-polarized. You can solder in either direction.

This is a very low cost part and can be sourced from almost any donor board or from Digikey, Mouser, Arrow, AliExpress.

Thank you very much @mon2

Ive ordered a capacitor book off amazon as will always be handy to have around

[mikay786]

Re: Lenovo Y50-70 PQ301 overheating

no luck with this board, power light comes on but no fan spin. CPU and GPU stone cold.

flashed the bios still no luck.

Anything else i can check?

[mon2]

Re: Lenovo Y50-70 PQ301 overheating

Review page 47 of the schematics.

With the adapter connected, what is the voltage of B+ ?