Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

[EugenF]

@Christian0734 I have the same defect on the same AHL50 motherboard. Did you solved the power issue ? Did you replaced PU2 ?

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

No point replacing PU2 unless the low resistance to GND reading is fixed on PL8. Simply another IC will go waste.

I've already ordered PWM Controller it will be useful for another board...

Remove PC43 and check resistance to GND on consumer side of PL8-is it same?

On PC43, on the PQ8 and PQ7 side, I'm grounded, on the other side, there are 50 ohms.

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Remove PC43 and check resistance to GND on consumer side of PL8-is it same?

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

In post #7, you have desoldered PQ8 out of the circuit. It shows OL (Open Loop), so we can assume it is in working condition for PQ801 and PQ805. The VGA CORE line mostly has low resistance. On the PU2, pin 19 (BOOT1), do you get +5V? Replace PU2 and see if there are any changes.

No point replacing PU2 unless the low resistance to GND reading is fixed on PL8. Simply another IC will go waste.

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

I may be wrong, but on the schematic, I see it's a 5V line whereas it's directly connected to the positive terminal of the CMOS battery, which should be at 3.2V. Either I'm misunderstanding the schematic, or there's an issue with the board.

Also, I remind you that the dual mosfet PQ8 has 50 Ω between gate 1 and source 2, on PQ801 there's 1 Ω between the gate and the source. And on PQ805 there's 15 Ω between the source and the drain.

PL8 is indeed 5V line and schematic is not wrong. You may be getting connectivity to cmos coz of low resistance on this coil.

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

RTC_VCC must not exceed 3.3V, as the +3VL line is connected to DC1 what is the Voltage pin 1 ?

On DC1 pin 1, there is 3.10V,
on pin 2 there is 3.316V,
and on pin 3 there is 3.017V.

In post #7, you have desoldered PQ8 out of the circuit. It shows OL (Open Loop), so we can assume it is in working condition for PQ801 and PQ805. The VGA CORE line mostly has low resistance. On the PU2, pin 19 (BOOT1), do you get +5V? Replace PU2 and see if there are any changes.

Pin 19 on PU2 there is 4.53V...

I'm going to order an RT8243AZQW, I already wanted to do it just in case, but there were 18 euros for shipping or wait for the delivery from Ali, so I've hesitated. But I just searched again, I found some on eBay in Germany, I'm going to place an order

[Techtiger]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

In post #7, you have desoldered PQ8 out of the circuit. It shows OL (Open Loop), so we can assume it is in working condition for PQ801 and PQ805. The VGA CORE line mostly has low resistance. On the PU2, pin 19 (BOOT1), do you get +5V? Replace PU2 and see if there are any changes.

[Techtiger]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

I may be wrong, but on the schematic, I see it's a 5V line whereas it's directly connected to the positive terminal of the CMOS battery, which should be at 3.2V. Either I'm misunderstanding the schematic, or there's an issue with the board.

Also, I remind you that the dual mosfet PQ8 has 50 Ω between gate 1 and source 2, on PQ801 there's 1 Ω between the gate and the source. And on PQ805 there's 15 Ω between the source and the drain.

RTC_VCC must not exceed 3.3V, as the +3VL line is connected to DC1 what is the Voltage pin 1 ?

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

So you have low resistance to GND on consumer side. Something is partially shorted.Its hard job as dc supply wont help much(voltage injection) as its not full shorting to GND. You need to manually check the components.The other risky way is to pump in more voltage on shorted side of PL8.As a safety precaution remove all coils from the mb if you want to inject higher voltage.However, its risky to some extent.

I may be wrong, but on the schematic, I see it's a 5V line whereas it's directly connected to the positive terminal of the CMOS battery, which should be at 3.2V. Either I'm misunderstanding the schematic, or there's an issue with the board.

Also, I remind you that the dual mosfet PQ8 has 50 Ω between gate 1 and source 2, on PQ801 there's 1 Ω between the gate and the source. And on PQ805 there's 15 Ω between the source and the drain.

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

So you have low resistance to GND on consumer side. Something is partially shorted.Its hard job as dc supply wont help much(voltage injection) as its not full shorting to GND. You need to manually check the components.The other risky way is to pump in more voltage on shorted side of PL8.As a safety precaution remove all coils from the mb if you want to inject higher voltage.However, its risky to some extent.

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Plese share the resistance to GND on both pads of PL8(coil desoldered). This will help us in understanding whether low resistance is on producer side or consumer side.

PL8 : 50 Ω on the side of PC43 and OL on the other

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Plese share the resistance to GND on both pads of PL8(coil desoldered). This will help us in understanding whether low resistance is on producer side or consumer side.

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

The only voltage I have on the coils when the board is powered is 3.179V on PL202 (near the battery port), and it doesn't change when I press the power button. It's very stable. I have no voltage present on the other coils.

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Btw, Do you get stable 3V/5V on coil before or after pressing power btn? Status of EC_ON?

On EC_ON, I have no voltage when the board is just receiving power, and I have a very precise 3.287V that is very stable when I press the power button.

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Btw, Do you get stable 3V/5V on coil before or after pressing power btn? Status of EC_ON?

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Sorry, i read it wrong. Consumption at 60mA or so will definitely not heat up anything much. Perhaps a closer look under microscope may give a clue.

I can't see anything noticeable when inspecting the board under the microscope.

To summarize, when I power the board with 19V, the current consumption is around 0.030A. When I press the power button, the consumption goes up to around 0.075A for about 10 seconds, then it drops back to 0.030A. I assume the SIO chip is trying to boot...

However, the UC2 BIOS chip is not powered at all (MX25L6473E).
From the schematic, I see that the +3V_PCH powering UC2 should be provided by QC30 and QC31, but I neither have PCH_PWR-EN nor +3VALW.
So my first conclusion would be that the SIO (EC) chip might be defective, right?

But we've tested a lot of pins, and it seems correct...
Another observation, when the board is powered with 19V, only the PU2 chip heats up, around 40° and about 50° when I press the power button.

Also, on the dual mosfet PQ8, there are 50 Homs between Gate 1 and source 2
And last observation from this morning, on PQ801 there is 1 Homs between the gate and the source
And on PQ805 there are 15 Homs between the source and the drain.

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Sorry, i read it wrong. Consumption at 60mA or so will definitely not heat up anything much. Perhaps a closer look under microscope may give a clue.

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

0.53A consumption indicates a short. What was the amp you pushed? Wait for 10-15 mins while injecting 1V/5A and then see if any area of the mb is warm.

Not 0.53A but 0.053A, which is almost nothing. With this current consumption, nothing is getting hot

I just took a photo, and I have a slightly higher current consumption today, 0.062A

The only thing that heats up a tiny bit with 1.5V is PU2

[mcplslg123]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

At 1V, the circuit is drawing 0.053A, and I'm not detecting any hot spots with my thermal camera. The resistance at the injection point measures 16 ohms.

0.53A consumption indicates a short. What was the amp you pushed? Wait for 10-15 mins while injecting 1V/5A and then see if any area of the mb is warm.

[Christian0734]

Re: Power Issue on HP AHL50/ABL52 LA-C701P Motherboard - UEFI Chip Not Powered

Have you removed the 5V coil(PL8) before injecting voltage? If no, then remove this coil first,allow the board to cool down a bit, then measure resistance to GND on both pads. One of the pads will show low resistance and you need to inject voltage here. I'll suggest to inject 1V/5A straight away. Wait for some time and see if anything heats up.

At 1V, the circuit is drawing 0.053A, and I'm not detecting any hot spots with my thermal camera. The resistance at the injection point measures 16 ohms.