Thinkpad E15 Gen2 (GE520) hot PU202

[danny34]

Hello folks,

I have a Thinkpad E15 Gen2 with an AMD processor. NM-C771 motherboard GE520.

The PU202 gets hot. I was able to measure that there is a short circuit to ground at pin 13 (+3VL). All other pins are ok.

I've already taken a few measurements, but can't find the cause of the short circuit. Do you have any ideas?

I have already soldered out the PU202, but there is still a short circuit on the conductor track

Thank you and best regards

[tomodachi]

You can inject 3 Volts to +3VL line and see what is up. Most likely EC or something.

[danny34]

Thank you for your answer.

On suspicion I soldered out the UE1 - IT8227E.
There is no longer a short circuit on pin 13 of the PU202.

When I measure between pin 1 (GND) and pin 121 (+3VL / +3VL_EC) on the unsoldered IT8227E, I have 0 ohms.
So I guess I just found the defective component.

[tomodachi]

Glad you found it, well done !

[danny34]

Thanks.
I have ordered a programmed IT8227E for my board and will report when it arrives and is soldered in.

[danny34]

The new programmed IT8227E arrived. I soldered it in directly and unfortunately the same problem as before... i.e. short circuit to +3VL and the PU202 gets hot

The old IT8227E had a short circuit between Pin1 & Pin121 when unsoldered. So it was definitely defective.

I now have a suspicion that it's exactly the same again, but I can't unsolder the IT8227E again until Tuesday to check.

Without the IT8227E, there was no short circuit at pin 13 on the PU202 and also not anywhere on the +3VL soldering pads of the IT8227E...

So what could trigger something like this?

[danny34]

The schematic

€: Sorry, Schematic attachment failed

[SMDFlea]

The schematic

Here -> https://www.badcaps.net/forum/troubl...29#post1708729

[danny34]

The E15 now works, but the next problem arises:

Image output only via HDMI, or the backlight of the display does not receive any voltage. Fuse F1 was blown.
I replaced this with the right one (3A32V) but unfortunately it keeps burning out.

Voltage at C10 (next to F1) with power supply is 9.24V. With 11.4V battery. And with both 12.5V.

Display has on the +LEDVDD pins 1-4 no short circuit to GND (40Mohms) and it also worked on another E15.

If I put a bridge between C10 (bridge the fuse) and a pin from the LCD (1-4), the notebook turns off.

I don't understand it.
Anyone an idea?

[mcplslg123]

Fuse keeps blowing for a reason. measure resistance to GND on both pads of F1
01.With display cable connected
02.Without display cable connected.