Hi everyone, I am hoping for a little help with an HP 250 G5 with motherboard LA-D704P with a Core i7-6500U. I am new to board repair but keen to learn.
I am sorry this post is quite long but I was trying to systematically work my way through things.
I don't know the history of the board – I bought it as part of a job lot.
I have attached a number of photos of both sides of the board. I cannot seem to find a schematic or boardview online.
When plugged in to DC power the power LED lights and the battery seems to charge. It will not POST however.
Immediately on plugging in the power lead the fan moves a fraction then stops.
I have tried - a different charger - removing power/battery and pressing the power button for 30 seconds – replacing memory - all to no avail. There is no visible corrosion on the board and I cannot see any physical damage to any components or broken solder joints.
I have checked the following:
1) DC Power connector – 19.75V present on board.
2) PQ202 and PQ203 – 19.75V at source and drain. No continuity between gate and source or gate and drain
3) PR203 – 19.75V both sides
4) PQ204 – 19.75V at drain, 3V at source. No continuity between gate/source or gate/drain
5) 3.3V at power button present
6) 3.3V present on pins 9, 22, 33, 96, 111, 125 of the ENE KB9022
Then moved on to check inductors/coils:
1) PL202 – 2.96V. Resistance to ground infinite
2) PL602 - 0V. Resistance to ground 1 ohm
3) PL1203- 0V. Resistance to ground 7.5 ohm
4) PL1205- 0V. Resistance to ground 4.5 ohm
5) PL1206 – 0V. Resistance to ground 15 ohm
6) PL9 – 0V. Resistance to ground 0.7 ohm
7) PL11 – 0V. Resistance to ground 240 ohms
8) PL8 – 0V but increases to 0.3V for about 5 seconds on pressing the power button then 0.6V for around a further 5 seconds before returning to 0V.
Also checked UC2 pin 8 and this seems to receive a current for a split second on plugging in the DC power. It is too quick for my digital multimeter to tell me the voltage
Then moved on the check some more MOSFETs in diode mode:
1) PQ1201 – Source to drain infinite in one direction and 450 volts in the other. Gate to drain infinite, gate to source 0V
2) PQ1202 – Source to drain 6V in both directions. Gate to drain 529V, gate to source 310V
3) PQ1206 – Source to drain 4V in both directions. Gate to drain 520V, gate to source 520V
4) PR1205 – Source to drain infinite in one direction and 450V in the other. Gate to drain infinite, gate to source 2V.
My microelectronic experience is minimal but it looks to me like there is a problem with PQ1202 and PQ1206 as well as several inductors shorting to ground. I may be very wrong however and I am happy to be corrected. I have no idea what to do next!
It would be great if someone could advise me on what to do next at this point. I am quite happy removing/replacing components if needed. I have access to soldering iron, hot air gun, wick and a power supply if needed too.
Many thanks in advance,
Bob.
I am sorry this post is quite long but I was trying to systematically work my way through things.
I don't know the history of the board – I bought it as part of a job lot.
I have attached a number of photos of both sides of the board. I cannot seem to find a schematic or boardview online.
When plugged in to DC power the power LED lights and the battery seems to charge. It will not POST however.
Immediately on plugging in the power lead the fan moves a fraction then stops.
I have tried - a different charger - removing power/battery and pressing the power button for 30 seconds – replacing memory - all to no avail. There is no visible corrosion on the board and I cannot see any physical damage to any components or broken solder joints.
I have checked the following:
1) DC Power connector – 19.75V present on board.
2) PQ202 and PQ203 – 19.75V at source and drain. No continuity between gate and source or gate and drain
3) PR203 – 19.75V both sides
4) PQ204 – 19.75V at drain, 3V at source. No continuity between gate/source or gate/drain
5) 3.3V at power button present
6) 3.3V present on pins 9, 22, 33, 96, 111, 125 of the ENE KB9022
Then moved on to check inductors/coils:
1) PL202 – 2.96V. Resistance to ground infinite
2) PL602 - 0V. Resistance to ground 1 ohm
3) PL1203- 0V. Resistance to ground 7.5 ohm
4) PL1205- 0V. Resistance to ground 4.5 ohm
5) PL1206 – 0V. Resistance to ground 15 ohm
6) PL9 – 0V. Resistance to ground 0.7 ohm
7) PL11 – 0V. Resistance to ground 240 ohms
8) PL8 – 0V but increases to 0.3V for about 5 seconds on pressing the power button then 0.6V for around a further 5 seconds before returning to 0V.
Also checked UC2 pin 8 and this seems to receive a current for a split second on plugging in the DC power. It is too quick for my digital multimeter to tell me the voltage
Then moved on the check some more MOSFETs in diode mode:
1) PQ1201 – Source to drain infinite in one direction and 450 volts in the other. Gate to drain infinite, gate to source 0V
2) PQ1202 – Source to drain 6V in both directions. Gate to drain 529V, gate to source 310V
3) PQ1206 – Source to drain 4V in both directions. Gate to drain 520V, gate to source 520V
4) PR1205 – Source to drain infinite in one direction and 450V in the other. Gate to drain infinite, gate to source 2V.
My microelectronic experience is minimal but it looks to me like there is a problem with PQ1202 and PQ1206 as well as several inductors shorting to ground. I may be very wrong however and I am happy to be corrected. I have no idea what to do next!
It would be great if someone could advise me on what to do next at this point. I am quite happy removing/replacing components if needed. I have access to soldering iron, hot air gun, wick and a power supply if needed too.
Many thanks in advance,
Bob.
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