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m1ch43lzm · 2025-06-23T14:36:27+00:00

That's bad if the resistance measurement is correct

PQ6204 is the high side MOSFET, if it's shorted S-G hopefully the RT6585 detected the fault, that's why the 3.3V and 5V supplies don't work

You can remove PQ6204 and measure it outside the board to confirm, set the hot air to 450-460 C

With the MOSFET removed measure again S-G pads on the board, resistance should be higher
If the MOSFET is shorted S-G outside the board, it's definitely faulty

Always measure resistance without power applied, don't connect the battery/charger until...

m1ch43lzm · 2025-06-23T11:44:45+00:00

⚠️ Warning, don't remove the MOSFETs or the IC yet, if you remove the low side MOSFET PQ6201 or the IC and apply power afterwards you will likely damage everything, as doing it will feed battery voltage to the 3v/5v lines

On a buck converter circuit, all components should be present before attempting to power on

I forgot to mention this, sorry

m1ch43lzm · 2025-06-23T02:45:04+00:00

Measure resistances between S-D, S-G, D-G on PQ6204, PQ6201
On PQ6202 (it's a dual MOSFET, source from MOSFET1 is connected to drain of MOSFET2, referred as S1D2), measure resistance between D1-S1D2, S1D2-G1, D1-G1, and between S2-S1D2, S2-G2, S1D2-G2

Measure voltages at PL6202 (5v), at the red dot, and PL6201 (3,3v) at the orange dot from the picture above
The red and orange lines are where the MOSFETs connect to the respective inductors

Also measure the resistances (in K ohms) across PR6209, PR6211, PR6210, PR6215, should be close to the value...

m1ch43lzm · 2025-06-23T01:03:05+00:00

Sorry, upload failed from my phone
Here it is...

m1ch43lzm · 06-21-2025, 07:18 PM

Hard to tell if there's no secondary damage
For C5503 I can barely see a bit of trace, I don't know if it's that one, I marked it with purple what I think it is, as I can't see a via on the ripped pad that goes to the other side of the board, and there's black glue around it that Lenovo likes to use on their buards
It isn't connected to the inductor L5501
You'll need a very fine wire, thinner than a hair for this

Depends how you're measuring the short, and how many ohms
Is it from top to bottom or from left to right?
Those caps are connected in...

m1ch43lzm · 06-21-2025, 06:45 PM

Try removing the TPS65994, don't solder it back, check for shorts between the pads (except those which are connected together on the schematics)

Only battery for now, as it won't work with the charger for obvious reasons, just want to check if the 3VALW and 5VALW are working before installing the TPS65994

If those rails become stable, reconnect the solder blobs PJ6201 and PJ6206, measure again if the voltages are stable 3.3v and 5v
If that works, laptop should be able to power on from battery, I want to get back to the point where laptop worked from battery but...

m1ch43lzm · 06-21-2025, 11:31 AM

Something definitely wrong, could be the TPS65994 or the soldering on it
There's no way to get those 2.5v if PJ6206 is open unless the TPS is badly soldered, there's a solder bridge somewhere, or has an internal fault, the 5v from the charger shouldn't go anywhere except the TPS itself and the input of the BQ, it shouldn't "leak" to 5VALW

It means only that whatever is in parallel to the cap is shorted
May be the cap itself, another cap in parallel on the same voltage rail but on a different physical location, an IC, anything...
One side of a cap...

m1ch43lzm · 06-21-2025, 10:34 AM

Since the Athlon 64 and Intel Nehalem arch (1st gen Core i-series) the memory controller is built-in to the CPU
Even Ryzen nowadays is a SOC by design, the "chipset" on desktop motherboards is AFAIK "just" an I/O expander for extra PCIe/SATA/USB...

All modern software are bloated these days.
Fixed it..., it's like the younger devs don't know how to optimize their software nowadays

If only I could run Win7 on Ryzen... There's missing drivers, starting from the USB 3.0/3.1 among other things
Tried that on the 2200g,...

m1ch43lzm · 06-21-2025, 08:20 AM

Those pads at PJ6201 and PJ6206 are solder jumpers, the board designers sometimes leave those in the final board design, as they're used for isolating the power supplies from the rest of the circuit when they design the prototype board

Sometimes they don't bother replacing those with solid traces, but i noticed they do with the 0 ohm resistors.. in the schematics and board view there's a resistor, but in the real board it's just a trace in that spot
About clearing those jumpers, sometimes a tiny bit of solder is still making a connection, it's good to double check for continuity...

m1ch43lzm · 06-21-2025, 07:01 AM

Schematics and board view here Posts #2 and #3
https://www.badcaps.net/forum/troubl...atic-boardview

Type 21BS is T14s gen 3
Check if it says NM-E091 on the silkscreen, near the onboard RAM

What's missing:
- C5401, C5402, C5403: 0.22uF 6.3v X5R 0201, on the data lines that go to the Thunderbolt IC
- C5503: 2.2uF 6.3v X5R 0402, it goes to a ball under the Thunderbolt IC, can't tell...

m1ch43lzm · 06-20-2025, 07:24 AM

That could mean there's an issue with either 3VALW or 5VALW, can also be related to the flickering on the USB-C meter

Try removing the solder blob at PJ6206, add fresh solder then use solder wick to clear it

With only the battery, Repeat the measurements at PJ6201, and either side of PJ6206, check if the 3.3v and 5v are stable now (laptop won't power on for now)

m1ch43lzm · 06-19-2025, 05:20 PM

11.7 is from the battery, that chip is doing its job for now

Check again
+3VALW at PJ6201
+5VALW at PJ6206

May need to scratch a bit those points with the probes, sometimes flux from manufacturing can form a non conductive layer over the solder blobs

The enable for 3VALW is present, so we should have 3.3v there with just the battery connected

-----
Sorry for the pictures not showing, only noticed the thumbnails working now, but the full image doesn't work

The admin is working on fixing the attachments, we...

m1ch43lzm · 06-19-2025, 04:41 PM

PC6231 is also a missing component, but the solder pads are there, go back to post #131 on the previous page, the pictures are back

, I marked it with a green line
Ok, now the 3.3v are enabled, you should get now 3VALW

m1ch43lzm · 06-19-2025, 04:35 PM

The voltage drops, because you set the current limit to 2A, you can try increasing the current limit to 3A

As it's drawing 2 amps something should be getting warm at least
Maybe it's the "Lenovo" IT8226 iC on the other side of the board?
Another trick with alcohol:
1. Add the drop of alcohol where you suspect the short, don't connect the wire yet, just solder one end to the shorted line
2. Touch the wire to the PSU + terminal you can see that the alcohol "moves" a bit, not necessarily evaporate, that depends on ambient temperature
...

m1ch43lzm · 06-18-2025, 06:59 PM

Forum issue, check here https://www.badcaps.net/forum/genera...e2#post3662095

It affects some users, currently there's an issue with the attachments, even attachments from yesterday don't work while the attachments from some users which didn't work yesterday work now, the admin said he's working on it

https://www.badcaps.net/forum/welcom.../3662039-apolo...

m1ch43lzm · 06-18-2025, 06:14 PM

That side with the 0.4 is the output after the inductor, not on the RT6585 side, solder a wire on the shorted side from.your bench PSU and do the voltage injection, start with 1V 2A

Check what gets hot, hopefully not the PCH as it would mean the end, replacing a PCH requires an expensive BGA rework station

May be also the IT8226 this time, I don't know if it has to be programmed first by an external programmer (expensive), or if the motherboard can program an empty/new EC, some boards do, some don't...

m1ch43lzm · 06-18-2025, 05:56 PM

Try setting your multimeter to volts, manual range appropriate for 3v, if it's auto range
If manual range set to 20v range

Just want to confirm if that chip is being told to enable the 3VALW and 5VALW outputs by the EC IT8227 (it's branded "Lenovo", a BGA chip which may have black glue on the corners, it it has the glue better not to try to remove it, as the pads on the PCB may become damaged)
Inspect the area first for stray solder blobs

Expected steady 3.3v on those enable signals
Also check RE4501 and RE4505, should be 0 ohm resistors, or...

m1ch43lzm · 06-18-2025, 04:23 PM

Now I'm beginning to think it's a hardware issue, with the 3.3v supply to the BIOS chip, the 5v supply, or a faulty flash chip, and the BIOS corruption/not going into BIOS setup is a side effect of that
As you said on the bios request thread it boots now into Windows but can't enter setup/change boot order anymore

You'll need a multimeter with sharp probes
Measure resistance across both R2802 and R2804, should be 0 ohms (same as touching the probes together), the schematics and board view linked above in post #27 will help to locate those parts

Also measure...

m1ch43lzm · 06-17-2025, 07:58 PM

I guess you could try removing PL602, or at least lifting one side of it, be careful not to melt the plastic connectors, then check if the short to GND on pin 8 of the RT6585 disappears
If that's the case, measure resistance to GND on either side of PL602, then inject voltage on the side it shows the short

m1ch43lzm · 06-17-2025, 07:09 PM

Maybe check the chip which switches 1_8VSUS to 1V8_AON
U53 SLG7NT402V
...

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