Lenovo ideapad 5 windows 11 update disable charging circuit?

[bogart219]

A fuse should read 0 ohms, so both fuses got blown if you're measuring resistance across them
Measure resistance to GND after the fuses, if not shorted (tens of K upwards) then the fuses may have gotten damaged due to heat

The flashing on the USB-C tester may indicate a fault with the TPS65994 or related circuit, sometimes ICs can get damaged when heat is applied for long time

You can start by measuring resistance to GND on the power pins of TPS65994, VIN_3V3_PD1 at CU207, VCC3_LDO_PD1 at CU209, or at the left side of RPU203, VCC1V5_LDO_PD at CU208, and 5VALW

mon2 what do you think?

Hey M1c, thanks for sticking with me. When i was heating those components, I put caption tape all around the component I was heating. That doesn't mean something still didn't get damaged by the heat.
Measuring the persistence to ground after the fuses, both read 1.2 meg. This means the fuses are blown, correct?

VIN_3V3_PD1 at CU207 = 1 MEG AND FALLING, LIKE ITS DISCHARGING.

VCC3_LDO_PD1 at CU209 = 1 MEG AND FALLING, LIKE ITS DISCHARGING.

RPU203 = 1 MEG AND FALLING, LIKE ITS DISCHARGING.

VCC1V5_LDO_PD at CU208 = 20 MEG

The 5VALW PINS 11,12 & 25,26 ON TPS65994 = NOTHING TO GROUND.

[bogart219]

Well I found the reason I believe that my usb-c tester was flashing when plugged in. It was a solder bridge from that cap I took out (PC5302). Once I cleaned that up, my usb-c tester was no longer flashing and back to 5 volts again. Now to find out what the other problem is.
Question, it appears that one fuse is bad . How would I look that up on Digikey? 5 amp 32 volt ceramic fuse? Also while I'm at it, get some some ceramic caps. 10 ohm 25 volt ones. What do you think? Thanks!

[m1ch43lzm]

https://www.digikey.com/en/products/...600M-2/8681948
Both fuses are suspect, you shouldn't have 15K across the fuse, they should be 0 ohm

Your fuses are marked "O", I think this one is an exact match, 6A 0603 fast acting fuse, the fuse markings vary between manufacturers which makes it even more confusing

But we know the rating on the charger, if your laptop specifies up to 100W charger, that is 20V*5A, the 5A fuse will be barely suitable, the 6A fuse has a little headroom to not blow during normal use
Sometimes components get changed on the final production version compared to the schematics

for the caps, "10uF 25V 0603 X5R" is what you should look for
https://www.digikey.com/en/products/...A8NRNC/3887527
There's a discount if you order 10 of more

[bogart219]

https://www.digikey.com/en/products/...600M-2/8681948
Both fuses are suspect, you shouldn't have 15K across the fuse, they should be 0 ohm

Your fuses are marked "O", I think this one is an exact match, 6A 0603 fast acting fuse, the fuse markings vary between manufacturers which makes it even more confusing

But we know the rating on the charger, if your laptop specifies up to 100W charger, that is 20V*5A, the 5A fuse will be barely suitable, the 6A fuse has a little headroom to not blow during normal use
Sometimes components get changed on the final production version compared to the schematics

for the caps, "10uF 25V 0603 X5R" is what you should look for
https://www.digikey.com/en/products/...A8NRNC/3887527
There's a discount if you order 10 of more

Thank You my man, I'm going to get those ordered right away! Thank you!!!!!!!!!!!!!

[m1ch43lzm]

If you don't have already, consider ordering some 27AWG 63/37 solder wire
It's easier to work with 63/37 lead/tin solder compared to lead free

[bogart219]

If you don't have already, consider ordering some 27AWG 63/37 solder wire
It's easier to work with 63/37 lead/tin solder compared to lead free

M1c,I'm glad you mentioned that. I have some solder that I've had for years. Would this one from radio shack be any good to use?



I got two 1 lb. spools of this solder that will last me for ever. I used this solder on thru hole work, which seemed to work good.



What do you think? If you think I should get something different I will.

[m1ch43lzm]

Sn62Pb36Ag2 should be fine as the melting point is 179 C (354 F), if what you already have is thin gauge (0.015") like the pictures it's OK to use
EDIT: Just noticed you wrote 0.022", it may work too, thinner gauge is easier for small components
Sn63Pb37 is more common, with a melting point of 183 C (361 F)
Those two types solidify quick, Sn60Pb40 stays molten for a while

The lead free stuff starts at 217 C (423 F) upwards, so it's good practice to replace with Sn63Pb37 (or Sn62Pb36Ag2 if you have it) when doing repairs, as manufacturers have to adhere to RoHS directives which restrict the use of leaded solder

Reference https://www.kester.com/knowledge-bas...perature-chart

[bogart219]

Sn62Pb36Ag2 should be fine as the melting point is 179 C (354 F), if what you already have is thin gauge (0.015") like the pictures it's OK to use
EDIT: Just noticed you wrote 0.022", it may work too, thinner gauge is easier for small components
Sn63Pb37 is more common, with a melting point of 183 C (361 F)
Those two types solidify quick, Sn60Pb40 stays molten for a while

The lead free stuff starts at 217 C (423 F) upwards, so it's good practice to replace with Sn63Pb37 (or Sn62Pb36Ag2 if you have it) when doing repairs, as manufacturers have to adhere to RoHS directives which restrict the use of leaded solder

Reference https://www.kester.com/knowledge-bas...perature-chart

Great, thanks.

[bogart219]

Thank Mods for getting this post back up. I got the parts in and installed I'm ready to continue my quest. Now where was I?

[bogart219]

When I started out trouble shooting this board here, with the battery plugged in I was getting 20 volts on my usb-c tester. Now I only get 5.2 volts with or without the battery plugged in. Do you think it would be a good time for some voltage injection and scan with the thermal camera?

[m1ch43lzm]

Does the laptop power on from battery only?

[bogart219]

Does the laptop power on from battery only?

NO

[m1ch43lzm]

Check voltage at the power button, it should have 3.3v on one of the pins

May need to remove the gasket to access the pins on the button itself

Just the motherboard, battery and daughter board for now

[bogart219]

I'm not reading any voltage anywhere on or near the power button.

[m1ch43lzm]

Let's go back to measuring voltages at the board
+3VL at PC6205, near PU6219
+3VALW at PJ6201
+5VL at PC6204 (one side is GND, the other is +5VL)
+5VALW at PJ6206
+3VALW_PCH at J2
+1.8VALW at PJ7912

+3VS at J5
+5VS at J4

if you have 3VL then you should have 3v at the power button as there's a pullup resistor on the board, I marked in green where I think you should have 3v, as the other pin from the button looks connected to GND
If you don't have 3VL on the board then check first if you have battery voltage at PJ6202

This one is becoming more complicated

[bogart219]

Mich, once more thank you for your help. i just hope that i didn't fruck something upI will do those test and post

[bogart219]

+3VL at PC6205, near PU6219 0 VOLTS
+3VALW at PJ6201 0 VOLTS
+5VL at PC6204 (one side is GND, the other is +5VL) 0 VOLTS THESE ARE WITH THE CHARGER ONLY PLUGGED IN.
+5VALW at PJ6206 0 VOLTS
+3VALW_PCH at J2 CAN'T FIND!
+1.8VALW at PJ7912 0 VOLTS

+3VS at J5 0 VOLTS
+5VS at J4 0 VOLTS


+3VL at PC6205, near PU6219 3.28 VOLTS
+3VALW at PJ6201 THE METER JUST RAPIDLY FLASHES!
+5VL at PC6204 (one side is GND, the other is +5VL) 5 VOLTS
+5VALW at PJ6206 THE METER JUST FLASHES RAPIDLY! THESE READINGS ARE WITH THE CHARGER AND THE BATTERY PLUGGED IN!
+3VALW_PCH at J2 CAN'T FIND?
+1.8VALW at PJ7912 .06 VOLTS

+3VS at J5 0 VOLTS
+5VS at J4 0 VOLTS

[m1ch43lzm]

You're missing both +3VALW and +5VALW, those are very important, if those are missing the power on sequence stops there
Measure +3VALW_EN on PC6230 (may be missing from the board, that's ok)
and +5VALW_EN on PC6231 (may be missing from the board)

Those should be high level, 3.3V, if they're 0v something went wrong
I've marked the location where you can measure those signals, in green for +5VALW_EN and yellow for +3VALW_EN

[bogart219]

You're missing both +3VALW and +5VALW, those are very important, if those are missing the power on sequence stops there
Measure +3VALW_EN on PC6230 (may be missing from the board, that's ok)
and +5VALW_EN on PC6231 (may be missing from the board)

Those should be high level, 3.3V, if they're 0v something went wrong
I've marked the location where you can measure those signals, in green for +5VALW_EN and yellow for +3VALW_EN

Good morning. with just the charger plugged in, 0 volts on both. with the charger and the battery plugged in, I get that rapid flashing OL symbol on the meter on both. Its seems like something is getting two sources of power at once or something.

[m1ch43lzm]

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 may be just traces, those feed 3VL to the EC


Pictures were lost , hopefully the admin will fix the forum issues

-----
I remember part of your follow-up question before the post was gone, it was about where the 5v goes
The 5v should go after the MOSFETs, on the fuses, even if the TPS65994 hadn't negotiated the 20v yet, it should pass those 5v to the BQ

It's a bit complicated, because the sequence I think is like this:

Charger only, or a completely empty battery
1. The TPS65994 passes the 5v to the BQ, which will boost those 5v to 13v (if battery is not present), creating the main power rail
2. The RT6585C (PU6219) generates the 3VL and 5VL by internal LDO regulators, from the main power rail
3. The EC (embedded controller) IT8227 (UE1) powered by 3VL, then tells the RT6585C to enable the 3VALW and 5VALW outputs
4. The EC also communicates with the TPS65994, feeding it the required firmware
5. then the TPS65994 negotiates the 20v
6. After getting the 20v, the BQ charger IC acts as a buck converter, generating the appropriate voltage for charging the battery/main power rail
7. We're in S5 power state, the EC waits for the power button press to turn on the laptop
Some laptops will also power on on their own if the RTC battery is not present or was unplugged before

With a working battery step 1 changes to:
1. The BQ connects the battery to the main power rail through a MOSFET
Skip 5 and 6 if charger not plugged in

Hopefully what I wrote is understandable, or maybe too technical?

Further reading: https://www.badcaps.net/forum/troubl...arging-circuit
Yours is Narrow VDC (NVDC) topology, buck-boost converter

The issues your laptop has right now are separate, if now we're not getting those voltages (3VALW, 5VALW), either due to a short, or it's not being told to enable, that's what I want to check first
Before you removed the MOSFETs it powered on from battery, so maybe a stray solder blob, or missing resistor that got dislodged somewhere