Hello, yes, I followed this guide. I would like to express my gratitude to Fust, who put in a tremendous amount of work to prepare the schematic. I hope that together we will be able to get our boards up and running. On my board, I replaced all the electrolytic capacitors, the damaged MOSFET Q29, the resonator X2, and there was a damaged trace near the transistor Q23. At the moment, I have an 18V power supply that turns on for 25ms. All PWM signals seem to be functioning correctly; however, the P12V_EN signal is not being output. I also located a damaged output O6 of the IC6 chip, and I'm waiting for a new CD4049 chip to arrive, which seems to be a suitable replacement. Below, I am attaching an image of what it looks like on the logic analyzer at this moment. Signal descriptions: D2 - VCC_PWM; D3 - P12V_PWM; D4 - P12V_EN; D5 - VINT_EN; D6 - 18V_INT_PWM; D7 - 18V_INT.

Regarding the power supply for the IC2 circuit, there is indeed a mistake in the schematic; it should look like what I have posted below. You should measure the voltage across the resistor R80 (the spot marked with a red arrow in the photo). When the button is pressed, there should be 0V there for about 30 seconds - with 5V_B_ENABLE in a low state. However, when IC2 is not powered, it should be around 12V; I have 11.7V.

@fust

Hello,

i admit i don't know how, but i managed to restore the function of Q30 and Ic2, now correctly turning on when i press the button. Or at least this is the current behavior, if it will keep working tomorrow nobody knows 😀

Now i'm back to the previous step : find why Q14 is not turning on. I ordered the replacement for IC7 and IC( tu rule out bad reading leading IC13 not to fire up Q14 and preventing my 18v to start.

Thanks
Stefano

@Ilcecco

Hi,
My board started working after replacing the TC4049; I now understand how the IC13 chip operates. First, it is necessary to check whether the VINT_EN_DRV output goes to a high state of +5V when the button is pressed. If there is an issue on the board, this state will remain for 25ms, so it cannot be checked with a regular multimeter. You need to use either an oscilloscope or a cheap logic analyzer; I have a Saleae-compatible 8-channel 24MHz one that costs just a few dollars. If VINT_EN_DRV goes to a high state of +5V, the VINT_EN signal should drop from 12V to a low state. To examine the VINT_EN signal, a voltage divider must be made for the analyzer, as it only accepts signals up to 5V, or you can use an oscilloscope. The MOSFET Q14 should be driven, and there should be a voltage present on capacitor C7. Again, the best tool for measuring this is an oscilloscope. If the VINT_EN_DRV high signal appears on pin P2 but there is no low signal on pin VINT_EN P19 of IC5 at the same time, then the IC5 chip is faulty.

@piotrosz

you are right, i was able to capture with an oscilloscope the 25ms up of VINT_DRV_EN so i assume something is preventing IC13 to keep it up.

I'm waiting for new IC for IC7 and IC8 should they give some bad voltage readings and forcing IC13 to shut down.

When you say you found a damaged output on IC6 you mean a phisical damage or there is something i can test/verify on IC6 to understand if it's working or not?

Thanks
Stefano

Hi,
it seems that the IC7 and IC8 integrated circuits are not involved in this process – these circuits are controlled by IC12 and are involved in charging the battery.

As for the damaged output of the IC6 on I6 I had a PWM signal, but it was no longer present on O6.

The operation of IC13 seems to be as follows:
1. The VINT_EN and 18V_INT_PWM signals are generated.
2. The 18V_INT voltage is produced and registered at the IC13_P2 pin (voltage sense).
3. After approximately 24ms, the VCC_PWM, P12V_PWM, NV9_PWM, and LCDV_PWM signals are generated.
4. The response from these signals in the form of PWM appears on IC13_P29, IC13_P30, IC13_P31, and IC13_P32 (through the IC6 circuit, which converts the 12V signal to 5V).
5. If the PWM signal on pins 29-32 of the IC13 circuit is correct, the P12_EN signal is output; otherwise, the operation of the IC13 circuit is interrupted.

If I were to diagnose this it now, I would do it in the following order:
1. Check the 12V V+(MAIN) voltage on all circuit inputs and the main MOSFETs.
2. Check the 5V_A voltage.
3. Check the enabling voltage of 5V_B."
4. Check if there is a VINT_EN signal.
5. Check if there is an 18V_INT_PWM signal.
6. Check if there is a voltage of 18V_INT on C6 and if the information about it is coming to IC13_P2.
7. Check if PWM signals appear on pins 29-32 of the IC13 chip.

For points 4-7, an oscilloscope is needed - the signals last for up to 25 ms after the button is pressed.

If you need any measurements for comparison, feel free to write. While I have the motherboard on top, I’m happy to help. I still need to verify the battery charging section. However, I’ll leave that for a later date. After connecting the power supply to the motherboard, it turned out that the computer freezes, or the keyboard doesn't work on the CMOS error display. I started checking the continuity connections from the keyboard to the KBC chip, which made the situation worse because now no message is displayed at all. I might have caused a short circuit because I didn't remove the battery from the motherboard during the measurements. Well, it seems that I still have a lot fun of me to get this laptop running .

Hello,

i'm following your suggestions but i'm stuck with a strange issue with step 6 :

tracing backwards from IC13 pin 2 back to C6 + i can see a 18v waveform for a while (oscilloscope in single shot mode, 50us, 5v, trigger 3v).

I can see it on the "entry" side of R57 coming from C6, but not on the other. Tested r57 and it's correctly 12k ohm. also continuity from 1c13 p2 to r96 to r57 is perfect and i see the 12k ohm from C6+ to the head of R96.

Of course i don't see anything as well on ic13 p2, not even triggering at 1v.

It doesn't make much sense to me, should i try to replace R57 despite the correct measurement ? i'm asking because such smd components are painful to replace and i don't see how it can show 12k ohm while being faulty...

also true that other than r57 i can't figure out any other reason why i don't see anything on r96 and ic13 p2...

Thanks
Stefano

Hi,
I believe that if R57 has the correct resistance, it is good. Check if you have a short to GND on p2 IC13/(the normal resistance to GND is 13kΩ R96 + R58)and whether the resistance value of R58 is correct, and if R58 is connected to ground on the other side. The voltage on p2 IC13 is about 5 times lower than the voltage on C6, so if all connections between IC13, R96, R58, and R57 are correct, there should be a voltage between the resistors R57 and R58. Below is my measurement from the oscilloscope; I have the probes set to 10x, so read 10V/DIV.

C1 - the voltage on C6, C2 - the voltage between R57 and R58, C3 - the voltage on P2 IC13; the waveforms of C2 and C3 are the same, which is why C2 is not visible and is obscured by C3.

Hello,

The resistance of ic13 p2 to ground is correct, i fear the problem is upstream.

This is the capture of what i get on c6 + it initially has little spikes up to 18v but then it sort of stabilizes at 10v before shutting down.

I guess your waveform is different, right ?

Stefano

Hi,
In this circuit, the Zener diode along with transistor Q27 is responsible for voltage stabilization. If the voltage stabilizes at 10V, first check/replace the Zener diode D9. If the Zener diode is functioning properly, check the connections and the rest of the circuit. You can also check diode D7 while you're at it.

Thanks piotrosz! I replaced q27 because i din't like the readings while testing it but didn't change much. I previously replaced A6 diodes including D7 (6 and 😎 so the only thing i'm missing is to investigate D9, can't try a replacement having no spares and will do asap.

I tested resistors, capacitors and continuity according to the diagram and they looks ok. Can be the 18V_INT_PWM that is not correctly formed if everhing else in this part of the circuit is ok?

Stefano

I think it's unlikely that the PWM signal is being generated incorrectly since it appears that IC13 is functioning properly, although anything can happen. To be sure, I'm attaching the waveforms of 18V_INT_PWM_DRV (C2) and 18V_INT_PWM (C3); it's a 78kHz signal with a duty cycle of approximately 20-80%.

In the meantime i checked also q17 to rule out that something downstream is preventing the +18v to stabilize properly.

I didn't find anything bad, it keeps stabilizing at around 10-11v on C6+ before shutting down. On the other end of L6 there is a good and stable +12v, capacitor c7 is fine.

Thinking about D9 it should let pass voltages over 18v back to q27 (if any) but being always below 18v on the d7/c6+ area there is nothing to let pass back. Am i wrong ?

Now i'm going to compare my PWM waveforms with yours...

I think i got it! Didn't touch base yet but i saw indeed a progress and of course it was the most stupid thing possible : poor gound connection for Q27 and Q29. Now i get for the usual little while about 16v on c6+ before it shuts down.

I can now see something also on IC13 P2 even if not the expected 3.6v.

it's also true i'm using exactly 12v from the power supply, i guess usually the main voltage from the outside usually was a little bit than 12.0v

Next step is move forward with the original troubleshooting guide and see what else is missing!

Ilcecco wrote on 2025-01-25, 21:41:

Thinking about D9 it should let pass voltages over 18v back to q27 (if any) but being always below 18v on the d7/c6+ area there is nothing to let pass back. Am i wrong ?

You are right, a functioning diode should work that way; however, a damaged diode may allow a voltage below 18V to pass to Q27, which would prevent the voltage at C6 from rising to the expected value.

I definitely have to try replacing D9 then. If i rise to 13v the main i then get about 16.5v on c6+ while if i keep 12.0 it stabilize at around 15.4.

I assume it should generate 18v with a 12v input, right ?

In the meantime i replaced all the push-pull transistors around the bigger Q and found a bad capacitor C38 on the ic13 reset line but nothing changed, it stills shut down right after generatig the 15/15v on the 18v rail.

Ilcecco wrote on 2025-01-26, 13:45:

I assume it should generate 18v with a 12v input, right ?

Yes, in my case, it's even 19V.

However, if D9 were to have a breakdown at 15V, it seems that it shouldn't depend on the input voltage - I don't have experience in this matter. You could also check the remaining components of the circuit, whether there is a proper ground on C7, what the resistance is relative to ground on C6+, and whether Q14 is appropriately driven to 0V on the gate. Is the connection of Q29, R34, and C7+ correct?"
What does the 18V_INT_PWN signal look like?

Hello,

I checked but i see nothing passing on the other side of D9, I assume then that it's correctly oreventing anything below 18v to flow.

I checked the PWM and DRV of 18v here you can see the waveforms. What is bothering me is that also the PWM is a little low and around 10.5v instead of 12v like main.

I checked grounding of c7 and all the other components of this section and they're fine.

What i'm thinking about is why i have a lower than expected voltage on both the PWM DRV and the exit of 18v...

Hello,

i just replaced IC5 with a new upa1600 and i desoldered and test D9 and it's correctly working at around 17.8v.

I have now 18v after the ramp fr 25ms then ic13 keeps to shut down 😀

Next step is to find what is missing to keep it alive, for sure there are almost 4v on IC13 P2 in order to sense the 18v.

Now investigating around Q7 where it seems that the PWM signal is very very short, few us instead of 25ms as well. I don't know if it's normal or not...

@fust @piotrosz

In the troubleshooting guide i see the PWM screenshots as a 12v with drops while i have the opposite : a zero tension with 12V spikes : am i measuring it wrong or this is "the" problem ?
I'm not able to figure out why i should see an inverted PWM like the one you can see in my previous images of the oscilloscope.

Summarizing the current status the only section i see somehow working now is the 18V that produce the right tension for 25ms, on the VCC section i see sort of PWM signal (very very short) but no VCC is generated. No PWM at all for 12V.

On IC5 i have a sort of flat 12V from P17 where i'm expecting to see a PWM for the N9V. How does the DRV from IC3 on pis 18 19 20 should look like ? I have a flat tension.

Is it correct that IC3 receives a 20Mhz clock on P1 and gives back to IC13 a 10Mhz clock from its P2? In the guide is reported that IC13 should have a 20Mhz clock but i see half of it (if i got it right).

Please tell me i'm not dealing with a broken IC13 or IC3 that would mean the board in unfixable 🙁