HP cdl50 la-d707p rev 1.0

[sylver]

Hello,
I've got a computer with a cdl50 la-d707p rev 1.0 motherboard (With GPU) that is not starting. I have no power/charging LED on the connector when pugging the power charger.
I tested output of PQ202 and PQ203 and I got about 25v which is OK from what I've seen.
When I press the power button, from what I've seen I should get 3-5v on PJP2 but I have 0v. The PJP2 pad is not shorted. I did of course tested that the power button is working correctly
I noticed that I have low resistance on PCV51/52/53 (around 15 ohms), but I don't know if it's a value to expect or not (but it seems quite low).
I'm not sure if I check the right things, but if anyone knowing this motherboard can guide me to the things to test, it would be great !

[mon2]

Re: HP cdl50 la-d707p rev 1.0

Hi.

1) my schematic database is showing different labels for the first 2 mosfets. Perhaps you can post your schematic to confirm ?

2) Check the DCIN at the first mosfet. Also post the voltages for the GATE, DRAIN for each of the first 2 mosfets.

PQB1 & PQB2


3) Next, power down - no adapter & no battery. Meter in resistance mode.

Check and post the resistance for the following junctions for each mosfet:

source & drain
source & gate
gate & drain

For guidance, review this great webpage - see the RESISTANCE chart:

http://electronicsbeliever.com/how-t...-is-defective/

[sylver]

Re: HP cdl50 la-d707p rev 1.0

Hi.

1) my schematic database is showing different labels for the first 2 mosfets. Perhaps you can post your schematic to confirm ?

2) Check the DCIN at the first mosfet. Also post the voltages for the GATE, DRAIN for each of the first 2 mosfets.

PQB1 & PQB2


3) Next, power down - no adapter & no battery. Meter in resistance mode.

Check and post the resistance for the following junctions for each mosfet:

source & drain
source & gate
gate & drain

For guidance, review this great webpage - see the RESISTANCE chart:

http://electronicsbeliever.com/how-t...-is-defective/

Hi thanks for your answer,
See attachements for the schematics, the labels are corresponding to the ones on the motherboard so I guess it's correct schematics in my case ! But it looks very similar to the one you have.

Regarding the values I have on these 2 MOSFETs :
PQ202 (MDU1512) :
S = 19.8v
G = 25.7v
D = 19.8v

PQ203 (AON7506) :
S = 19.8v
G = 25.7v
D = 19.8v

For resistance values I have several Mohms for each junctions for both MOSFETs !

I guess the issue is not from one of these MOSFETs but I may be wrong ... The point is that I'm not sure about what to check next and which power rails should be on when the computer is off but connected to power supply (I don't use the battery yet)

[mon2]

Re: HP cdl50 la-d707p rev 1.0

Yes, the first 2 mosfets are ok.

Remove all power. Meter in resistance mode.

1) Check and post the resistance to ground on inductor (coil) PL9, pin # 1

2) Post the resistance between:

mosfet PQ7: pin 2-3-4 and pin 9 (this is 50% of this dual mosfet device)
* drain 1 & source 1

PQ7: pin 9 & pin 1
* source 1 and gate 1

PQ7: pin 1 & 2-3-4
* gate 1 and drain 1

Then interested in the readings for the 2nd half of this device

PQ7: pin 5-6-7 & pin 9
* source 2 and drain 2

PQ7: pin 5-6-7 & pin 8
* source 2 and gate 2

PQ7: pin 8 & pin 9
* gate 2 and drain 2

3) Meter in DC volts. Apply the adapter.

What are the voltage readings for:

a) PQ7, pin 2-3-4 ? Should be about 19VDC = DCIN from adapter.

b) PQ7, pin 1 (G1) ?

c) PQ7, pin 8 (G2) ?

[sylver]

Re: HP cdl50 la-d707p rev 1.0

Yes, the first 2 mosfets are ok.

Remove all power. Meter in resistance mode.

1) Check and post the resistance to ground on inductor (coil) PL9, pin # 1

2) Post the resistance between:

mosfet PQ7: pin 2-3-4 and pin 9 (this is 50% of this dual mosfet device)
* drain 1 & source 1

PQ7: pin 9 & pin 1
* source 1 and gate 1

PQ7: pin 1 & 2-3-4
* gate 1 and drain 1

Then interested in the readings for the 2nd half of this device

PQ7: pin 5-6-7 & pin 9
* source 2 and drain 2

PQ7: pin 5-6-7 & pin 8
* source 2 and gate 2

PQ7: pin 8 & pin 9
* gate 2 and drain 2

3) Meter in DC volts. Apply the adapter.

What are the voltage readings for:

a) PQ7, pin 2-3-4 ? Should be about 19VDC = DCIN from adapter.

b) PQ7, pin 1 (G1) ?

c) PQ7, pin 8 (G2) ?

Thanks,
here are the results :
PL9, pin # 1 to ground : 1Mohms

PQ7 :
2-3-4/9 (taken on PU2 pin 9 as pin 9 is not accessible on PQ7) : 2Mohms
9/1 : infinite
1/2-3-4 : 150kohms
5-6-7/9 : 1Mohms
5-6-7/8 : 6Mohms
8/9 : 6Mohms

PQ7 voltages :
2-3-4 : 19.8v
1 : 0v
8 : 0v
9 : 0v

I guess PU2 is supposed to generate 3v to enable PQ7 ?

[mon2]

Re: HP cdl50 la-d707p rev 1.0

1) what is the voltage on pin # 12 of PU2 ? (ENLDO)

2) voltage on pin # 15 of PU2 ? (LDO3)

3) voltage on pin # 14 of PU2 ? (LDO5)

4) voltage of +5valwp rail @ PL8, pin # 2 ?

5) PU2 is not turning on the dual mosfet @ PQ7. The resistance readings appear to be ok for PQ7.

PU2 may be defective and needs to be replaced.

Post your voltage reading of +5valwp.