Lenovo ideapad 5 windows 11 update disable charging circuit?

[bogart219]

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 the MOSFET is replaced with an appropriate one
Charger won't work anyway as the TPS65994 is missing from the board

Dammit, I measured S TO G AGAIN ON 6204 and got 1.7 meg. (I tripled checked this time). My bad. Thanks for the hot air setting too btw.

[m1ch43lzm]

I can't think of anything else that could cause the 3.3V and 5V supplies to not start, but the LDO outputs work
Maybe an out of spec resistor in that area, compare with the schematics, page 60 and the boardview

With power removed (no battery, no charger) measure resistance across PR6204 and PR6205, should be 2.2 ohms (meter may read a little higher due to probes resistance, note the value of the probes touching together)
PR6201: 15K
PR6202: 5.1k

With only battery connected, only if the MOSFETs and RT6585C IC are in place
If both enable signals 3VALW_EN and 5VALW_EN are present (3.3v) and the outputs at the inductors are not shorted to GND, it should work, supplying the 3.3V and 5V at the inductors PL6201 and PL6202

[bogart219]

I can't think of anything else that could cause the 3.3V and 5V supplies to not start, but the LDO outputs work
Maybe an out of spec resistor in that area, compare with the schematics, page 60 and the boardview

With power removed (no battery, no charger) measure resistance across PR6204 and PR6205, should be 2.2 ohms (meter may read a little higher due to probes resistance, note the value of the probes touching together)
PR6201: 15K
PR6202: 5.1k

With only battery connected, only if the MOSFETs and RT6585C IC are in place
If both enable signals 3VALW_EN and 5VALW_EN are present (3.3v) and the outputs at the inductors are not shorted to GND, it should work, supplying the 3.3V and 5V at the inductors PL6201 and PL6202

Those four resistors all checked out good. The only thing off the board now is the TPS chip and a cap PC5302. With the battery plugged in testing to ground those two solder pads you highlighted in the picture, the meter just kept flashing from 1.5 to 2.5 volts, back and forth.

[m1ch43lzm]

Those four resistors all checked out good. The only thing off the board now is the TPS chip and a cap PC5302. With the battery plugged in testing to ground those two solder pads you highlighted in the picture, the meter just kept flashing from 1.5 to 2.5 volts, back and forth.

That could be the cause of everything right now, those should be stable 3.3v

Measure resistance of RE4535 (it's smaller than a flea, near one BIOS chip UB2, your board has 2) and RE4539 (near the EC UE1, its a chip branded "Lenovo" IT8227VG), those are pullups for the 3.3V and 5V enable signals, both should measure 100K, why did the Lenovo engineers place them in completely different locations...

If the resistors are OK, maybe the issue is the EC, if it has black glue on the corners don't attempt to remove it, that glue that Lenovo likes is very difficult to remove, you may damage the pads on the board; also it's a BGA chip that would need to be reballed
Also the EC as far as I know needs to be programmed after replacement, and the programmer for those is very expensive

[bogart219]

That could be the cause of everything right now, those should be stable 3.3v

Measure resistance of RE4535 (it's smaller than a flea, near one BIOS chip UB2, your board has 2) and RE4539 (near the EC UE1, its a chip branded "Lenovo" IT8227VG), those are pullups for the 3.3V and 5V enable signals, both should measure 100K, why did the Lenovo engineers place them in completely different locations...

If the resistors are OK, maybe the issue is the EC, if it has black glue on the corners don't attempt to remove it, that glue that Lenovo likes is very difficult to remove, you may damage the pads on the board; also it's a BGA chip that would need to be reballed
Also the EC as far as I know needs to be programmed after replacement, and the programmer for those is very expensive

Both of those resistors checked out good. Yeah, I can't mess with that EC chip. It seems this flashing started after something I did but what? The question is is this flashing the result of a component touching a ground where it shouldn't (that would be a short right)? Or is a component getting power from two sources at once? I will examine the areas I screwed with again to see if I can find anything fishy. Thanks again my man, I'm finding out how difficult it can be to diagnose a motherboard problem when its sitting in front of you, let alone trying to find a problem posting back and forth with a noob such as myself!!!!!!!

[bogart219]

Mich, I'm just spit balling here and tell me what you think of this: I asked this above, The question is is this flashing the result of a component touching a ground where it shouldn't (that would be a short right)? Or is a component getting power from two sources at once? Now if the flashing is from a short to ground, you would think something would heat up wouldn't you? I just checked the board with the charger and battery plugged in with my thermal camera and the only thing I seen light up a little was the BQ chip and that was only at 80c. Now would it be feasible to try some voltage injection? I got a voltage injection tool a few days ago. at this point do you think that would tell us anything?

[m1ch43lzm]

Mich, I'm just spit balling here and tell me what you think of this: I asked this above, The question is is this flashing the result of a component touching a ground where it shouldn't (that would be a short right)? Or is a component getting power from two sources at once? Now if the flashing is from a short to ground, you would think something would heat up wouldn't you? I just checked the board with the charger and battery plugged in with my thermal camera and the only thing I seen light up a little was the BQ chip and that was only at 80c. Now would it be feasible to try some voltage injection? I got a voltage injection tool a few days ago. at this point do you think that would tell us anything?

Charger connected won't do anything right now, as we don't have the TPS65994

only 80C on the BQ?, that's burning hot if you touch it with your fingers
The BQ is supposed to connect the battery to the main rail, labeled 20VB+ on the schematics, turning on PQ5305
I totally forgot that PQ5305 has an internal diode from D -|>|- S, so the battery power goes first through the internal diode of PQ5305 to the main rail, that also goes to pin 22 of the BQ
Then the BQ is supposed to turn on PQ5305
SInce PQ5305 is a P channel MOSFET, a faulty/shorted BQ could also turn on this MOSFET

Disconnect all power, measure resistance from G of PQ5305 (located close to the battery connector) to GND
Also measure resistance from S-D, S-G, D-G

On the BQ (always with power disconnected, no battery, nothing)
Measure resistance to GND at pins 12 and 13 (CHARGE_SDA, CHARGE_SCL)
Measure resistance to GND at pin 8, a suitable test point is at PC5319/PR5318 at the side closest to the BQ

The flashing you see on the enable lines, could be that the 3VL is unstable; or the EC doesn't like something, as it has connections to the BQ25710 and the TPS65994, so the EC keeps restarting over and over, it could be pulses ef 3.3V on the enable signals but you can't measure that with a multimeter, you need an osciloscope if you want to check this "flashing"

[bogart219]

Correction, That temp on the BQ chip was 80 degrees F, not C. I forgot I changed that on my thermal camera, I got C on my mind from the Atten and my soldering equipment.

PQ5305 : FROM G TO GND. - .9 MEG BQ CHIP, 12 TO GND. - .6 MEG 13 TO GND. - .6 MEG PIN 8 TO GND. - 136K

S-D - 1 MEG
S-G - 2 OHMS
D-G - 10 MEG

Don't understand when you said this " a suitable test point is at PC5319/PR5318 at the side closest to the BQ ". I was able to test pin 8 on the BQ ok.

I have a scope that I bought 5 years ago but never used it

[bogart219]

Mich, do these two caps look like they they could be shorted? Maybe one or the other or both, I believe they are connected to each other. I tested them to gnd. with my meter in the diode mode and both beeped on both ends of the cap.
They are PC3005 AND PC3018 LOCATED NEAR PU3001. What say you?

[bogart219]

It probably doesn't make a difference but just to be sure: OK?

[m1ch43lzm]

Mich, do these two caps look like they they could be shorted? Maybe one or the other or both, I believe they are connected to each other. I tested them to gnd. with my meter in the diode mode and both beeped on both ends of the cap.
They are PC3005 AND PC3018 LOCATED NEAR PU3001. What say you?

It depends on the reading on your meter; around 100 ohms, maybe a bit less, may be a bit higher is completely normal, as it's the 1.2V power supply for the RAM
Usually low voltage and high current supplies have low resistance to GND, how low, it depends; for example on a good working CPU the reading may be around 5-10 ohms, maybe a little less depending on CPU type
Measure again in resistance mode
Yes, both are in parallel. The reading should be the same at PJ3002 or PL3001

It probably doesn't make a difference but just to be sure: OK?

Those are slightly bigger in size (3.3mm*3.3mm) than the originals (3mm*3mm), which ones you received?

https://www.digikey.com/en/products/...6LDK-7/6010148
This one is the exact same size (3mm*3mm), has similar specs to the original (Id 46.2A, 7.5mOhm Rds(on))

[bogart219]

I'm confused now. I measured the original mosfet that I took off the board with a dial caliper and it measured 3.0mm x 3.0mm. The ones I got are 3.3mm x 3.3 mm as you said. The bigger ones are a pain in the ass cause you can't see any of the traces underneath it and I just centered it where I thought it looked the best.

Did you notice this?
Looking at the data sheets, the mos I got and the mos you found has a different Pin layout for the gate and source. Could this be the whole problem we are having? The one you found will work right?
Give me the word and I will order the ones you found!





Wonder why the Digikey tech guy didn't suggest the one you found?