Hi guys,
& another one comes along..
Symptom/Problem
-2sec to black. Image visible if using torch light.
-If i leave the monitor on longer, 20 sec later the backlight will lit up again for about 2sec... then off.
-Power LED steady blue
Description/what's been done.. or not
- Age around 2-3years, But it is an export set so no warranty.
- No schematics at hand
- Have not replaced all caps because they all 'look' to be super fine. But will replace them if advised to do so.
- Use another panel (my 'dead' HP f1905 and working hp w20) to test ccfl (subtitute them one at a time or all at once), but still 2sec to black result.
Unplugged & measured resistances
- no short in between pins of D101(in circuit) & D107 (out of circuit)
- U201 BD9893F Pin 16 (Vcc) not shorted to Pin 6 (Gnd)
- on T301 (in-circuit)
: P1 =open to all
: P2 =1.2ohms to P3, increasing to P4, open to the rest,
: P3 =1.2ohms to P2, increasing to P4, open to the rest,
: P4 =increasing until max to P2, P3
: S1 to S2 =897ohms,
: S3 to S4 =initially 1500-1520ohms but drops to 943ohms after re-testing it again & again
: S1&S2 to S3&S4 = 191k ohms
Plugged & measured Voltages = backlight on (off)
- across Big cap = 330V (330V)
- CN2
13V = 12.2V (14.19) both unstable
5V = 5.2V (5.21V) both stable
3V = 3.27 (3.27) both stable
- U201 BD9893F
Pin 16 (VCC) = 11.01 (10.9)
Pin 9 (Comp) = 0.61 (0.51)
- on T301
: S1 & S2 - Over volt (almost busted my DMM again)
: S3 & S4 - 6.2-6.5V?!!
So 1 side of the transformer is reading less voltage than the other.. So is this transformer faulty & need to be replaced?.
Or are there other components or test points that i missed out?..
Am i troubleshooting it correctly?..
Hope the experts here can guide me along.. again thanks..
& another one comes along..
Symptom/Problem
-2sec to black. Image visible if using torch light.
-If i leave the monitor on longer, 20 sec later the backlight will lit up again for about 2sec... then off.
-Power LED steady blue
Description/what's been done.. or not
- Age around 2-3years, But it is an export set so no warranty.
- No schematics at hand
- Have not replaced all caps because they all 'look' to be super fine. But will replace them if advised to do so.
- Use another panel (my 'dead' HP f1905 and working hp w20) to test ccfl (subtitute them one at a time or all at once), but still 2sec to black result.
Unplugged & measured resistances
- no short in between pins of D101(in circuit) & D107 (out of circuit)
- U201 BD9893F Pin 16 (Vcc) not shorted to Pin 6 (Gnd)
- on T301 (in-circuit)
: P1 =open to all
: P2 =1.2ohms to P3, increasing to P4, open to the rest,
: P3 =1.2ohms to P2, increasing to P4, open to the rest,
: P4 =increasing until max to P2, P3
: S1 to S2 =897ohms,
: S3 to S4 =initially 1500-1520ohms but drops to 943ohms after re-testing it again & again
: S1&S2 to S3&S4 = 191k ohms
Plugged & measured Voltages = backlight on (off)
- across Big cap = 330V (330V)
- CN2
13V = 12.2V (14.19) both unstable
5V = 5.2V (5.21V) both stable
3V = 3.27 (3.27) both stable
- U201 BD9893F
Pin 16 (VCC) = 11.01 (10.9)
Pin 9 (Comp) = 0.61 (0.51)
- on T301
: S1 & S2 - Over volt (almost busted my DMM again)
: S3 & S4 - 6.2-6.5V?!!
So 1 side of the transformer is reading less voltage than the other.. So is this transformer faulty & need to be replaced?.
Or are there other components or test points that i missed out?..
Am i troubleshooting it correctly?..
Hope the experts here can guide me along.. again thanks..
Comment