Hi guys,
I need some help in next steps to troubleshoot a PSU board.
I'm trying to save the board from becoming E-waste and hoping to learn a few things in the attempt.
This is my own TV and I just have basic electronics knowledge.
-------
TV : Sharp LC 60LE655U
Symptom : After a lightning strike with TV in standby, the TV does not turn on.
When switched on from mains, the LED light flashes :2 long followed by 2 short (repeats)
Per the manual of a similar Sharp TV (LC60LE640U), this indicates : Power Supply error 2 (*2) UR +13V error
I kept the TV unplugged for a while and also tried to reset using CH- and VOL+ while plugging in TV. No change.
Power supply unit : DPS-167CP A
Pictures at http://www.shopjimmy.com/sharp-runtk...-led-board.htm
With board connected to the TV, the main board momentarily sends a voltage on PS_ON and then immediately after that LED flashes begin.
I assume it tried to turn on the PSU, found an error and stopped trying to turn it on.
With the board on bench:-
Output from Bridge Rectifier BD7001 = 171 V (across output pins)
No visible sign of swollen capacitors, burn marks or leaks.
POWER SUPPLY BOARD PD connector pinout:
PD-1-2 = PNL12V
PD-3-4-9-10-11-12 = GND
PD-5-6-7-8 = UR13.2V ----> 0 V even when PS-ON is supplied
PD-13 = AC_DET ------>3.3 V when PS-ON is supplied using 1k resistor from BU5V
PD-14 = PS_ON
PD-15 = BU5V ----> 5V present
PD-16 = PNL-POW (Panel Power signal (input ))
PD-17 = PWM1
PD-18-20 = N.C.
PD-19 = DIMMER
PD-21 = OFL
PD-22 = ERROR
PD-23 = PWM2
PD-24 = STB
Without supplying PS-ON, BU5V is 5V and all other pins are at 0 V.
When I supply PS-ON using 1k resistor from BU5V
1. PS-ON = 4.6 V
2. Large capacitors 7800A/B have voltage = 412V (without PS-ON , cap voltage = 170V)
3. AC_DET = 3.3 V
4. All other pins = 0 V
Resistance across fusible resistor R7601 (in-circuit) = 0.1 ohm
----
Please let me know what else I can do to find the problems with this board.
Also, please point out any mistakes in my analysis so far.
Thanks
I need some help in next steps to troubleshoot a PSU board.
I'm trying to save the board from becoming E-waste and hoping to learn a few things in the attempt.
This is my own TV and I just have basic electronics knowledge.
-------
TV : Sharp LC 60LE655U
Symptom : After a lightning strike with TV in standby, the TV does not turn on.
When switched on from mains, the LED light flashes :2 long followed by 2 short (repeats)
Per the manual of a similar Sharp TV (LC60LE640U), this indicates : Power Supply error 2 (*2) UR +13V error
I kept the TV unplugged for a while and also tried to reset using CH- and VOL+ while plugging in TV. No change.
Power supply unit : DPS-167CP A
Pictures at http://www.shopjimmy.com/sharp-runtk...-led-board.htm
With board connected to the TV, the main board momentarily sends a voltage on PS_ON and then immediately after that LED flashes begin.
I assume it tried to turn on the PSU, found an error and stopped trying to turn it on.
With the board on bench:-
Output from Bridge Rectifier BD7001 = 171 V (across output pins)
No visible sign of swollen capacitors, burn marks or leaks.
POWER SUPPLY BOARD PD connector pinout:
PD-1-2 = PNL12V
PD-3-4-9-10-11-12 = GND
PD-5-6-7-8 = UR13.2V ----> 0 V even when PS-ON is supplied
PD-13 = AC_DET ------>3.3 V when PS-ON is supplied using 1k resistor from BU5V
PD-14 = PS_ON
PD-15 = BU5V ----> 5V present
PD-16 = PNL-POW (Panel Power signal (input ))
PD-17 = PWM1
PD-18-20 = N.C.
PD-19 = DIMMER
PD-21 = OFL
PD-22 = ERROR
PD-23 = PWM2
PD-24 = STB
Without supplying PS-ON, BU5V is 5V and all other pins are at 0 V.
When I supply PS-ON using 1k resistor from BU5V
1. PS-ON = 4.6 V
2. Large capacitors 7800A/B have voltage = 412V (without PS-ON , cap voltage = 170V)
3. AC_DET = 3.3 V
4. All other pins = 0 V
Resistance across fusible resistor R7601 (in-circuit) = 0.1 ohm
----
Please let me know what else I can do to find the problems with this board.
Also, please point out any mistakes in my analysis so far.
Thanks
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