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Panasonic TH-L50B6D LED 1 Blink Code
downunder:
Best to use a resistor. It protects the circuits connected to the pins from inrush current as these pins never go above 3.5V during normal
operation. Never know what ICs or switching transistors are in line.
About identifying the pins....a bit haphazard and tricky. You can eliminate maybe 3 ground pins which should read near zero ohms to the chassis ground, eg the tuner case. I explained how to identify the Standby 5V pin. A couple of pins
Power-On and BL-On will read near zero volts in standby, and rise rapidly towards 3.5V when power is activated. However other pins, eg PWM may also imitate this and rise as well. A bit hairy, I'd say.
BTW: Do you have 24V at LD1, and what voltages do you get at the pins on LD3?
BookWormStud:
--- Quote from: downunder on August 15, 2017,06:08:21 ---
Best to use a resistor. It protects the circuits connected to the pins from inrush current as these pins never go above 3.5V during normal
operation. Never know what ICs or switching transistors are in line.
About identifying the pins....a bit haphazard and tricky. You can eliminate maybe 3 ground pins which should read near zero ohms to the chassis ground, eg the tuner case. I explained how to identify the Standby 5V pin. A couple of pins
Power-On and BL-On will read near zero volts in standby, and rise rapidly towards 3.5V when power is activated. However other pins, eg PWM may also imitate this and rise as well. A bit hairy, I'd say.
BTW: Do you have 24V at LD1, and what voltages do you get at the pins on LD3?
--- End quote ---
I checked all the voltages you can check here
Also attaching the Circuit Diagrams of Connectors of P & LD-Boards from service manual of TX-L50B6B because I checked the Model No. & Part No. which matches with that of my TV.
Hope you can make something out of it.
downunder:
At a guess, P-AO9, pin 6 = Standby 5V (stable), pin 9 = Power-On (stable), pin11 = BL-ON (all over the place).
P4, pin 3 = BL-ON (all over the place).
LD3, pins 3 and 9, LED supply volts, should be stable.
Suggestion: cut the lead going to pin 11 of P-AO9 in a place where it can be resoldered later on. Make sure all plugs are in place. Then place your resistor between pins 6 and 11 of P- AO9. Now you are controlling the backlights, not the A-board. If pin 11 is now stable, then the A-board is causing your previous fluctuations. If the backlight don't light up, I'd say you have dead LED/LEDs in the display panel - LG panel, is it? Quite common.
Don't suppose you have a LED tester? My guess is based on the voltages you have supplied and may not be accurate. Good work on your attachments.
Bruce
BookWormStud:
--- Quote from: downunder on August 16, 2017,06:47:05 ---
At a guess, P-AO9, pin 6 = Standby 5V (stable), pin 9 = Power-On (stable), pin11 = BL-ON (all over the place).
P4, pin 3 = BL-ON (all over the place).
LD3, pins 3 and 9, LED supply volts, should be stable.
Suggestion: cut the lead going to pin 11 of P-AO9 in a place where it can be resoldered later on. Make sure all plugs are in place. Then place your resistor between pins 6 and 11 of P- AO9. Now you are controlling the backlights, not the A-board. If pin 11 is now stable, then the A-board is causing your previous fluctuations. If the backlight don't light up, I'd say you have dead LED/LEDs in the display panel - LG panel, is it? Quite common.
Don't suppose you have a LED tester? My guess is based on the voltages you have supplied and may not be accurate. Good work on your attachments.
Bruce
--- End quote ---
First of all Thanks for even reading that.
Secondly, P-A09 Connector (Stand By) I wrote Pin 3 = 133V instead of 0.133V Sorry for that.
No I don't have a LED Tester. Sorry.
You said Pin 3 = BL_ON at P4 and Pin 11 = BL_ON at P2, But the diagram says Pin 2 & Pin 12 Respectively. Please Explain.
About LD3 Pin 3 & Pin 9, voltages fluctuate cause Backlights are turning ON & OFF.
Yes It has the LG Panel the infamous LC500DUE (SF)(R1)
Also, if I cut the Pin 11 wire attach it to a resistor how am I be able to connect to Pin 6 with the connector plugged in. Or should I do it like this
downunder:
The BL-ON function of pin on P2 (14 pin) I have surmised from the behaviour of the voltages you provided. You say it fluctuates between 1V and 4.5V. I could be wrong, but 4.5V this sounds like the level BL-ON would reach. The functions you have allocated to P2 on your attachment (last post) - are they the real deal as per service manual for your model? This keeps confusing me, the different number of pins in various attachments.
Re the resistor, my intention was for you to do it with all connectors in place. You can either force it into the top of P2 or solder it to the relevant pins on the underside of P2. THen, A-Board supplies Power-On, you supply BL-ON.
Bruce
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