Hi all,
A minor issue but I thought I would ask...
I have a Sony KDL-32L4000, north american chassis CZ1. It came to me with a bad A (main) board, with the symptoms:
1) No standby LED light when plugged in
2) Green LED turns on via top button or remote, but no backlight or picture.
Initially I thought is was the G (power supply) board, but that checked out OK. When I disconnected the A board connector for the backlight control, the backlights lit up just fine, but still no picture. I think I have located the problem stalling the power-on process for this TV, but until I am sure I will leave that for another post.
While trying to figure this out, I ordered a replacement A board off of ebay to verify that it was really an A board problem. (Note that there are at least 3 different A board part numbers for this TV/chassis, depending on the LCD panel manufacturer and TV serial number, and that many of them on ebay are mislabeled with the wrong number!) The replacement A board worked, and fixed the TV back to good working order. Hurray!
Except there is one minor issue. With this replacement A-board, the red standby LED still does not light when the TV is plugged in or when it is powered off. Now I'm sure you are saying "Check the LED!", but I did that. The problem is not the LED itself. There is simply no voltage going from the A board to the standby LED pin on the connector for the IR/LED boards. I checked the LED driver transistor pair. They look fine, and are connected via some resistors directly to a pin on the MT5380 processor, and the trace seems to be OK (I removed the heatsink to verify this). So it looks like this pin out on the MT5380 is just not going high when the unit is in standby.
And the crazy thing about this is that BOTH the old and the new A-board exhibit this problem.
So, my question to the forum is:
Has anyone else seen this? Is the failed standby LED a common problem on this TV, or other similar Sony TVs, or TVs in general? Since the Standby LED might be annoying for use in a bedroom, I thought maybe this was a feature to disable it, but I see no option for this in the setup menu. I did reset the new A-board to factory settings using the factory service menu, but still no standby LED.
The lacking standby LED is a minor issue, but I worry that if this is really a dead output pin on the MT5380, does this foretell future problems with this main board? Do you think it is an electrical problem in the processor, or could it possibly be a firmware problem?
Thanks for listening!
John
A minor issue but I thought I would ask...
I have a Sony KDL-32L4000, north american chassis CZ1. It came to me with a bad A (main) board, with the symptoms:
1) No standby LED light when plugged in
2) Green LED turns on via top button or remote, but no backlight or picture.
Initially I thought is was the G (power supply) board, but that checked out OK. When I disconnected the A board connector for the backlight control, the backlights lit up just fine, but still no picture. I think I have located the problem stalling the power-on process for this TV, but until I am sure I will leave that for another post.
While trying to figure this out, I ordered a replacement A board off of ebay to verify that it was really an A board problem. (Note that there are at least 3 different A board part numbers for this TV/chassis, depending on the LCD panel manufacturer and TV serial number, and that many of them on ebay are mislabeled with the wrong number!) The replacement A board worked, and fixed the TV back to good working order. Hurray!
Except there is one minor issue. With this replacement A-board, the red standby LED still does not light when the TV is plugged in or when it is powered off. Now I'm sure you are saying "Check the LED!", but I did that. The problem is not the LED itself. There is simply no voltage going from the A board to the standby LED pin on the connector for the IR/LED boards. I checked the LED driver transistor pair. They look fine, and are connected via some resistors directly to a pin on the MT5380 processor, and the trace seems to be OK (I removed the heatsink to verify this). So it looks like this pin out on the MT5380 is just not going high when the unit is in standby.
And the crazy thing about this is that BOTH the old and the new A-board exhibit this problem.
So, my question to the forum is:
Has anyone else seen this? Is the failed standby LED a common problem on this TV, or other similar Sony TVs, or TVs in general? Since the Standby LED might be annoying for use in a bedroom, I thought maybe this was a feature to disable it, but I see no option for this in the setup menu. I did reset the new A-board to factory settings using the factory service menu, but still no standby LED.
The lacking standby LED is a minor issue, but I worry that if this is really a dead output pin on the MT5380, does this foretell future problems with this main board? Do you think it is an electrical problem in the processor, or could it possibly be a firmware problem?
Thanks for listening!
John
