Dell Latitude 7390 mb:DDA30 LA-F292P - nie widzi zasilacza

Witam szanownych kolegów. Na stole Dell Latitude 7390 mb:DDA30 LA-F292P. Laptop nie wykrywa zasilacza - testowane 3 różnych - oryginalnych. Zauważyłem, że jest 19,5V na 3 nodze układu DT21 w pobliżu gniazda zasilania (usb-c). Laptop startuje na baterii i działa normalnie. Na samym zasilaczu sprzęt nie uruchamia się. W biosie komunikat ac adapter - not installed. Proszę o pomoc z próbie naprawy płyty.

Hello!

Measure the following voltages to ground with the power supply connected to the port JUSBC1:
- On pins 1, 4, 8 of transistors PQ1200, PQ1202.
- On pin 3 of transistor PQ1209.
- On pin 5 of transistor PQ1224.

Transistor PQ1209 pin count:

Thanks for the response matic .

Measurements:

jusbc1:

1-0V
2-0V
3-0V
4-19,5
5-0V
6-0V
7-0V
8-0V
9-19,5
10-0V
11-0V
12-0V


pq1200 (chip absent)
1-19,5V
4-0V
8-19.5V

pq1202
1-19,5V
4-1.8V
8-19,5V

pq1209
3-0V

pq1224
5-3,3V

Measure the following voltages to ground with the power supply connected to the port JUSBC1:
- On pins 1, 4, 8 of transistor PQ1203.
- On pins 1, 2, 3, 8 of chip PU1201.
- On all pins of chip PU1202.

matic napisal/-a:Measure the following voltages to ground with the power supply connected to the port JUSBC1:
- On pins 1, 4, 8 of transistor PQ1203.
- On pins 1, 2, 3, 8 of chip PU1201.
- On all pins of chip PU1202.

PQ1203
1-19,5V
4-19,5V
8-19,5V

PU1201
1-0V
2-1,55V
3-0V
8-3,3V

I can't find PU1202 ... the board is poorly described
PU1202 is also missing on boardview..

pawel1978 napisal/-a:PQ1203
1-19,5V
4-19,5V
8-19,5V

With these measurements the PQ1203 is damaged. Check it.

pawel1978 napisal/-a:I can't find PU1202 ... the board is poorly described
PU1202 is also missing on boardview..

Really


- Measure the voltages to ground on pins 5, 6, 7 of chip PU1201.
- Measure the voltages to ground on pins 1, 2 of transistors PQ1208, PQ1219.
Transistors PQ1208, PQ1219 pin count:

I confirm the measurement with pq1203 ... when tested with an ohmmeter, the mosfet seems to be operational.

PU1202 is as in the picture - I don't know why on my boardview it didn't search.
Measurements with pu1202:
1-3.3V
2-3,3V
3-0V
4-3,3V
5-3,3V

pu1201
5-0,03V
6-1,55V
7-0V

PQ1208
1-0V
2-3,3V

PQ1219
1-0,03V
2-0V

pawel1978 napisal/-a:I confirm the measurement with pq1203 ... when tested with an ohmmeter, the mosfet seems to be operational.

Please, specify the following resistance measurements on this transistor (transistor soldered to the board):
- Between pin 1 and pin 4.
- Between pin 1 and pin 8.
- Between pin 4 and pin 8.

matic napisal/-a:

pawel1978 napisal/-a:I confirm the measurement with pq1203 ... when tested with an ohmmeter, the mosfet seems to be operational.

Please, specify the following resistance measurements on this transistor (transistor soldered to the board):
- Between pin 1 and pin 4.
- Between pin 1 and pin 8.
- Between pin 4 and pin 8.

1-4 - 500kohm and 500kohm with reverse polarity
1-8 - 6kohm and 3,3Mohm with reverse polarity
4-8 - 630kohm and 3Mohm with reverse polarity


edit: I replaced pq1203 preventively with AON7409 - unfortunately, the measurements voltages on 1.4 and 8 are identical

Remove the transistor PQ1203 from the board and remeasure the voltages to ground on pads 1, 4, 8 on the place of this transistor.

matic napisal/-a:Remove the transistor PQ1203 from the board and remeasure the voltages to ground on pads 1, 4, 8 on the place of this transistor.

1-19,5V
4-19,5V
8-0V

Measure the voltages to ground on pins 1, 4, 8 of transistors PQ1202, PQ1203 with PQ1202 soldered to the board and PQ1203 removed from the board.

matic napisal/-a:Measure the voltages to ground on pins 1, 4, 8 of transistors PQ1202, PQ1203 with PQ1202 soldered to the board and PQ1203 removed from the board.

PQ 1203 taken off the board.

Measurement
PQ 1202 :
1-19,5V
4-1,8V
8-19.5V

pads under PQ 1203

1-19,5V
4-19,5V
8-19,5V

The previous measurement of the pq1203 pads must have been done incorrectly because there is 19.5V on the 8th leg

Measure the voltage on pin 5 of PQ1207.
Measure the voltages on all pins of PQ1204.

Machine napisal/-a:Measure the voltage on pin 5 of PQ1207.
Measure the voltages on all pins of PQ1204.

Measurements without pq1203

pq1207 , p.5 (g1) - 0V

pq1204 -
D-19,5V
G-4,8V
S-19.5V

Remove the diode PD1202 from the board and remeasure the voltages to ground on all pins on the place of transistor PQ1203 (PQ1203 should be removed from the board).

matic napisal/-a:Remove the diode PD1202 from the board and remeasure the voltages to ground on all pins on the place of transistor PQ1203 (PQ1203 should be removed from the board).

PD1202 removed,

pads under PQ1203

1-0V
4-0V
8-19,5V

Set the multimeter to the diode test mode and test the diode PD1202 out of the board.
What forward and reverse voltage you read from the multimeter?

matic napisal/-a:Set the multimeter to the diode test mode and test the diode PD1202 out of the board.
What forward and reverse voltage you read from the multimeter?

PD1202 - multimeter measurement in diode mode - no conduction in one direction, reading 253 in the other direction.

I'm not sure where to check the forward and reverse voltage.. if on pads from pq1203 it comes out

1-0V / 0V
4-0V / 0V
8-19.5V / -19.5V

pawel1978 napisal/-a:I'm not sure where to check the forward and reverse voltage..

Forward voltage = Red probe of multimeter to the anode pin of diode and black probe to the cathode pin of diode.
Reverse voltage = Red probe of multimeter to the cathode pin of diode and black probe to the anode pin of diode.
So you already did it.

pawel1978 napisal/-a:PD1202 - multimeter measurement in diode mode - no conduction in one direction

So the reverse voltage is out of range of multimeter.

pawel1978 napisal/-a:reading 253 in the other direction.

That's the forward voltage, which means 0.253V

pawel1978 napisal/-a:pads under PQ 1203
1-19,5V
4-19,5V
8-19,5V

Are these measurements correct?
If the voltage on pad 8 is 19.5V, I expect the voltage 19.247V on pad 1 on the place of these transistor.