Hi!
I have an intermittent issue with my LG 55LA740V LED TV that I would like some help diagnosing. Any ideas welcome.
A dark vertical band with about 1/6th of the screen width (probably a single LED strip) appears maybe 50% of the times I turn on the TV - the other 50%, it works just fine.
This is in detail what happens.
1. Power on - the panel goes up to high brightness. No band, all LED:s seem just fine.
2. It shows the LG Logo, and starts lowering the brightness of the panel.
3. The TV finishes booting and starts showing input.
4. The dark vertical band appears!
5. On the power/LED driver board (EAX64905801), a diagnostic LED LD701 starts repeatedly flashing four times. (This does NOT happen when the TV starts up normally, so the boards "knows" something is going on.
6. At the top of the power board, there are two ribbon connectors that goes into the panel with a total of 6 driver voltages pins. 5 of them measures about 50V, and one (no. 3) measures only 7V. At normal startup, all of them measures 50V. Unfortunately I have not been able to measure the pins without the panel attached, since the TV seems to shutdown this output quickly and shows another repeating "3 blink" on the little red led on the power board.
Questions:
What does the red led "4 blink" sequence on the power board really mean. Anybody with a service manual? This would really be interesting to know.
Is there any service menu on the LG 55LAxxx televisions that can help me?
Theories:
1. Defective EAX64905801 Power/LED Driver board. Solution: Get a new and change it - easy and quite cheap to try.
2. The LED strip in question is defective and somehow causes the driver board to output only 7V. Maybe the led 4-flash tells something about this. Solution: Change the LED strip - harder, but can be done.
3. Some odd error in the mainboard causes the local dimming to tell the power board to dim the actual LED strip. Seems quite far-fetched.
//Thomas Heder, Sweden
I have an intermittent issue with my LG 55LA740V LED TV that I would like some help diagnosing. Any ideas welcome.
A dark vertical band with about 1/6th of the screen width (probably a single LED strip) appears maybe 50% of the times I turn on the TV - the other 50%, it works just fine.
This is in detail what happens.
1. Power on - the panel goes up to high brightness. No band, all LED:s seem just fine.
2. It shows the LG Logo, and starts lowering the brightness of the panel.
3. The TV finishes booting and starts showing input.
4. The dark vertical band appears!
5. On the power/LED driver board (EAX64905801), a diagnostic LED LD701 starts repeatedly flashing four times. (This does NOT happen when the TV starts up normally, so the boards "knows" something is going on.
6. At the top of the power board, there are two ribbon connectors that goes into the panel with a total of 6 driver voltages pins. 5 of them measures about 50V, and one (no. 3) measures only 7V. At normal startup, all of them measures 50V. Unfortunately I have not been able to measure the pins without the panel attached, since the TV seems to shutdown this output quickly and shows another repeating "3 blink" on the little red led on the power board.
Questions:
What does the red led "4 blink" sequence on the power board really mean. Anybody with a service manual? This would really be interesting to know.
Is there any service menu on the LG 55LAxxx televisions that can help me?
Theories:
1. Defective EAX64905801 Power/LED Driver board. Solution: Get a new and change it - easy and quite cheap to try.
2. The LED strip in question is defective and somehow causes the driver board to output only 7V. Maybe the led 4-flash tells something about this. Solution: Change the LED strip - harder, but can be done.
3. Some odd error in the mainboard causes the local dimming to tell the power board to dim the actual LED strip. Seems quite far-fetched.
//Thomas Heder, Sweden
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