Morning All!
Just picked up a 40” Proscan, Model: 40LD45Q
Plug unit in and the red standby light appears. Press the power button and it turns to solid blue. It will hold this state indefinitely until you press the power button again or remove power. I removed the cover and did a close visual inspection of all boards, front and back and found nothing abnormal looking. The backlights do not even attempt to turn on. I hear no relay clicks or any other sound when the power button is pushed.
I have searched Hi and Low for a service manual or schematic and have come up empty handed. My thoughts are that the Mainboard is sending the signal to the power supply board but something is failing on the power supply board.
I replaced the capacitors, near the area of CON2F as shown in the pictures. (Those were just new oddball ones I had laying around, all I could find). The original capacitors showed no visual sign's of failure. I went ahead and replaced what I had to rule that out. (Desperately needing to order a cap tester!) My intention is to order a full cap kit once I figure out where the problem is. If I’m understanding this correctly, a low signal on the FB pin of CN3 is normal, that if it was greater than 2volts then a fault from the inverter board would be present.
Where should I start troubleshooting next? I want to dig deep into this power supply and identify the cause of the problem instead of just ordering a new one. Thank you for any ideas and suggestions.
Measurements of:
CON2F
`````````STBY Power ON
+5VSB 5.26 5.33
+5V 0.02 5.33
+12 0.0 13.30
+12 NC NC
ADJ .02 3.49
PS/ON 0.10 4.92
+5V 0.02 5.33
+12V NC NC
On/Off 0.02 3.43
CN3
VOC 0.0 13.3
FB 0.0 0.0
LD 0.0 12.6
LD 0.0 12.6
CON3F
24V 1.67 26.0
24V 1.67 26.0
(Sorry for the formating, not sure of a better way to do this.)
Just picked up a 40” Proscan, Model: 40LD45Q
Plug unit in and the red standby light appears. Press the power button and it turns to solid blue. It will hold this state indefinitely until you press the power button again or remove power. I removed the cover and did a close visual inspection of all boards, front and back and found nothing abnormal looking. The backlights do not even attempt to turn on. I hear no relay clicks or any other sound when the power button is pushed.
I have searched Hi and Low for a service manual or schematic and have come up empty handed. My thoughts are that the Mainboard is sending the signal to the power supply board but something is failing on the power supply board.
I replaced the capacitors, near the area of CON2F as shown in the pictures. (Those were just new oddball ones I had laying around, all I could find). The original capacitors showed no visual sign's of failure. I went ahead and replaced what I had to rule that out. (Desperately needing to order a cap tester!) My intention is to order a full cap kit once I figure out where the problem is. If I’m understanding this correctly, a low signal on the FB pin of CN3 is normal, that if it was greater than 2volts then a fault from the inverter board would be present.
Where should I start troubleshooting next? I want to dig deep into this power supply and identify the cause of the problem instead of just ordering a new one. Thank you for any ideas and suggestions.
Measurements of:
CON2F
`````````STBY Power ON
+5VSB 5.26 5.33
+5V 0.02 5.33
+12 0.0 13.30
+12 NC NC
ADJ .02 3.49
PS/ON 0.10 4.92
+5V 0.02 5.33
+12V NC NC
On/Off 0.02 3.43
CN3
VOC 0.0 13.3
FB 0.0 0.0
LD 0.0 12.6
LD 0.0 12.6
CON3F
24V 1.67 26.0
24V 1.67 26.0
(Sorry for the formating, not sure of a better way to do this.)
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