I have a Dell U2312H that suddenly won't turn on anymore. The display and
backlight won't turn on; the blue power LED stays off even when I press the
power button. These have the L0281-1N power boards which are the same ones used
for the Dell P2312H and P2012H, among others (according to Google).
Unfortunately I can't find any schematics for this particular board.
I have made some measurements to some of the components from the power board
and main board. These were all tested in circuit (i.e. I didn't solder them
out). Readings are ordered by pins (e.g. 1, 2, 3, etc.). Diodes were tested
using the continuity tester of my multimeter; however, I don't know what the
units for these are. I have upload the images of the boards to imgur. If you
need a close up picture of some parts of the board, please don't hesitate to
notify me. Thank you!
Power Board
I805
AUK
81826
A78R12PI
12v, 0.8mv, 0v, 0.263v
I802 (Optocoupler)
L1125
817D
Y
Red to Pin 1 + Black to Pin 2: 567
Black to Pin 1 + Red to Pin 2: 567
I801 (PWM Controller)
LD7575BGS
112731
Pins 1 - 4: -0.48v - -0.58v
Pins 6 - 8: -0.35, -0.02, 0.66
Q121
D482
BA1U15
Black to S + Red to G: 16.31MΩ
Black to S + Red to D: 0.82MΩ (and increasing)
Black to G + Red to D: 1.11MΩ
D805
pec 1329
ER1002FCT
Black to Pin 1 + Red to Pin 2: 581 and increasing
Black to Pin 1 + Red to Pin 3: 001
Black to Pin 2 + Red to Pin 3: 395
Black to Pin 2 + Red to Pin 1: 395
D812
pec 1349
ER1002FCT
Black to Pin 1 + Red to Pin 2: 892
Black to Pin 1 + Red to Pin 3: 002
Black to Pin 2 + Red to Pin 3: 399
Black to Pin 2 + Red to Pin 1: 399
D810
N 1G
FCQS20A065
Black to Pin 1 + Red to Pin 2: 481 and increasing
Black to Pin 1 + Red to Pin 3: 002
Black to Pin 2 + Red to Pin 3: 135
Black to Pin 2 + Red to Pin 1: 135
Q803
A
2761I
124 125
Black to S + Red to G: 0.148MΩ
Black to S + Red to D: 1.2MΩ
Black to G + Red to D: 1.4MΩ
R811
1.1Ω (should be 0.36Ω 2WJ)
Main Board
I301
N252
G1084-33
0v, 0.18v, 5.0v
I302
UTC
LD1117AG
12A010GTG
0v, 0v, 0.18v
I308
D|| 1fB
17-33
0v, 0v, 0v
backlight won't turn on; the blue power LED stays off even when I press the
power button. These have the L0281-1N power boards which are the same ones used
for the Dell P2312H and P2012H, among others (according to Google).
Unfortunately I can't find any schematics for this particular board.
I have made some measurements to some of the components from the power board
and main board. These were all tested in circuit (i.e. I didn't solder them
out). Readings are ordered by pins (e.g. 1, 2, 3, etc.). Diodes were tested
using the continuity tester of my multimeter; however, I don't know what the
units for these are. I have upload the images of the boards to imgur. If you
need a close up picture of some parts of the board, please don't hesitate to
notify me. Thank you!
Power Board
I805
AUK
81826
A78R12PI
12v, 0.8mv, 0v, 0.263v
I802 (Optocoupler)
L1125
817D
Y
Red to Pin 1 + Black to Pin 2: 567
Black to Pin 1 + Red to Pin 2: 567
I801 (PWM Controller)
LD7575BGS
112731
Pins 1 - 4: -0.48v - -0.58v
Pins 6 - 8: -0.35, -0.02, 0.66
Q121
D482
BA1U15
Black to S + Red to G: 16.31MΩ
Black to S + Red to D: 0.82MΩ (and increasing)
Black to G + Red to D: 1.11MΩ
D805
pec 1329
ER1002FCT
Black to Pin 1 + Red to Pin 2: 581 and increasing
Black to Pin 1 + Red to Pin 3: 001
Black to Pin 2 + Red to Pin 3: 395
Black to Pin 2 + Red to Pin 1: 395
D812
pec 1349
ER1002FCT
Black to Pin 1 + Red to Pin 2: 892
Black to Pin 1 + Red to Pin 3: 002
Black to Pin 2 + Red to Pin 3: 399
Black to Pin 2 + Red to Pin 1: 399
D810
N 1G
FCQS20A065
Black to Pin 1 + Red to Pin 2: 481 and increasing
Black to Pin 1 + Red to Pin 3: 002
Black to Pin 2 + Red to Pin 3: 135
Black to Pin 2 + Red to Pin 1: 135
Q803
A
2761I
124 125
Black to S + Red to G: 0.148MΩ
Black to S + Red to D: 1.2MΩ
Black to G + Red to D: 1.4MΩ
R811
1.1Ω (should be 0.36Ω 2WJ)
Main Board
I301
N252
G1084-33
0v, 0.18v, 5.0v
I302
UTC
LD1117AG
12A010GTG
0v, 0v, 0.18v
I308
D|| 1fB
17-33
0v, 0v, 0v
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