Lenovo Ideapad 320-15ikb: Comes on and goes off

[Nagyesz]

Hey guys, I have a Lenovo Ideapad 320-15ikb NM-B241 rev:1.0.
After turning it on, it runs for a few seconds then shuts off completely. No screen, no fan. After shutdown, a red light comes on and off fast. I've been trying to troubleshoot this for days now. It's never been opened up; the Lenovo sticker is still intact.

(!)I tried with a different BIOS battery, without any ribbon cables, on battery power, without the keyboard, and it's always the same.

Any insights on what might be causing this?

[Nagyesz]

Yea I actually managed to short something
Pl401 went from 21.3kohm to 0.04ohm 😶

[mon2]

Link the schematics if available but in the schematics forum only.

https://forums.lenovo.com/t5/Lenovo-...20on%20battery.

Suspecting…

The laptop is working on battery only, the battery is weak or discharged (LED blink code) and the power adapter leg is not charging the battery nor powering up the logic board

[Nagyesz]

Thank you very much for your response, what should I look at first to identify the problem with the laptop?

I made a video, maybe the problem is more visible this way: https://i.imgur.com/z8GerhV.mp4

[mon2]

See attached.

Update - first check the voltage to ground on EACH side of the fuse @ PF101.





Next...

1) Remove all power. Meter in resistance mode. Measure the resistance to ground of the drain pins (5-6-7-8) on mosfet PQ312 - any of these pins is ok. We are checking to see if there is a shorted component on the main power rail which is after the highlighted 2 x DCin mosfets.

2) If the resistance is not too low, power up. Meter in DC volts mode (30v or higher or auto-scaling mode). Carefully measure the voltage to ground on each of the highlighted DCin mosfets.

Check the voltage to ground of PQ311:

Drain pins (5-6-7-8) ; any of these pins is ok - voltage should match the power adapter voltage since this is the INPUT to the board.
gate pin (4)
source (1-2-3)

Repeat for the 2nd DCin mosfet @ PQ312.

Post each measurement.

[Nagyesz]

Just as I was dismantling it to prepare for measurement, I noticed two interesting things (1 for sure) (it had never been disassembled before). What do you suggest?

[mon2]

Pour ipa (alcohol) on these regions of the board and clean it up with cotton swabs / q-tips.

[Nagyesz]

Here are the measurements: I'm not particularly skilled with a meter, so if any value seems really odd, I'll remeasure.

fuse@ PF101 (without power cable). both side is the same 0.7 mV sometimes 0.2mV or 0(!) for both of them:

pq311 pin 5 is 20.4V , pin 4 (gate) 26.2V pin 1-2-3 20.4V
PQ312 pin 5 is 20.4V , pin 4 (gate) 26.2V pin 1-2-3 20.4V

(I cleaned with alcohol but still the same issue)

[mon2]

The voltage measurements on PQ311 / PQ312 confirm that your fuse @ PF101 is not blown.

1) In the shared video - was the battery connected or disconnected? Is the power adapter connected or disconnected?

2) With the battery AND power adapter connected, carefully measure the voltage to ground @ PL302 inductor. This inductor is usually grey in color and will have 2 contact leads. This inductor is in series with the battery charge leg of the logic board. Need to know what voltage is present here.

3) Does this logic board function ok if using ONLY the power adapter?

[Nagyesz]

1. It doesn't matter whether the battery is in or not; if I start it with just that, it still shuts off after a few seconds, but the battery disconnected and power adapter was connected

2. 2 min

3. As I said, unfortunately, it doesn't matter how I start it, it reacts the same way as in the video.

[Nagyesz]

@ PL302 inductor both legs are 8.5V (charger and battery plugged in)

Edit(!) Battery is charging, but when I turn it on, it runs for a few seconds without any fan or image, then it turns off along with the charging, and then it starts charging again.

[mon2]

See attached. Connect both, the battery and power adapter.

Carefully measure the voltage to ground of each pin on the battery connector. If this is not possible to do, consider the alternative test method.

Remove all power -> meter in DIODE mode. Short your meter probes and the meter will tone beep.

Place the red meter probe, yes RED, to ground (any metal shield is ok). Black meter probe onto the point to test.

Test each pin on the battery connector (no battery / no power adapter if using DIODE mode of testing).

We are checking to see if the TVS ESD diodes @ PD201 are defective or not.

[Nagyesz]

Here you go: First option;
1 pin: 8,5V 2 pin: 8.5V pin 3 3.2V pin 4 3.2V pin 5 0.3V pin 6 0V pin 7 0V pin 8 0V

Edit with method 2: only 8,7 beeping

[mon2]

pin 3 3.2V pin 4 3.2V

SMBUS lines are ok and the TVS ESD diodes are not blown.

Suggest to investigate each and every inductor onboard. They are usually grey in color and with 2 contact leads. Remove all power -> meter in resistance mode (not diode mode). One meter probe on the inductor leg (either side is ok); other meter probe to ground. Note the resistance in ohms.

Continue to investigate all inductors on the board and note any suspects that have a low resistance reading. We are checking for shorted parts on the logic board which may cause a higher than normal current draw and the local power rail will turn OFF.

[Nagyesz]

pl500 60 ohm
pl 501 150 ohm
pl1003 4.3 ohm
pl1001 7.1ohm
pl1002 11.7 ohm
pl302 5Mohm (megohm) (?)(!)
pl402 0.3 Mohm (megohm)(?)(!)
Pl401 20Kohm (kiloohm)(?)(!)

These I found

The ones with question marks I could barely measure; their values kept changing constantly, slowly going up or down. I don't know if I measured them incorrectly, but these are what I got.

Edit: Descriptions could be misleading; I quickly skimmed over what was written there

[Nagyesz]

I made a brief summary, unfortunately I still don't know what else could be the problem
If anyone happens to have any ideas, I would appreciate it!

[mcplslg123]

UC4 pins seems like bridged with extra solder. Check it once

[Nagyesz]

I measured it, and I find it a bit odd that I only measured 5.1 volts on the 11th leg. ( power cable is only plugged)

[SMDFlea]

I measured it, and I find it a bit odd that I only measured 5.1 volts on the 11th leg. ( power cable is only plugged)

What youve measured is pin 4 ,look at the number 1 (and the white line next to it) and 8 around the IC .

[Nagyesz]

Thank you, I really overlooked it. However, could this mean something?

[SMDFlea]

Thank you, I really overlooked it. However, could this mean something?

Pin 4 is ok 5 volts Always on voltage. Pin 10 looks like it might be bridged or it has something on the solder. QC2 might have a broken trace