Blinks Error Code Circuit Explanation - Panasonic TC-P42X1 Technical Manual

8 Blinks Error Code Circuit Explanation

There is an extra SOS Detect circuit in the Sustain board. This circuit is
used to monitor for physical connection between the panel and the SS board.
Under normal condition, Q16280 is on.
When Q16280 is on, a low is provided to the anode of D16280 (D280).
If one of the FPC cables is open, Q16280 turns off and a high is provided to the
anode of D16280 (D280). This high is provided to pin 66 of the CPU in the
A board. When this happens, the TV shuts down and the power LED blinks
8 times.
The energy recovery circuit is also used to monitor the operation of the sustain drive
circuit. If this circuit is triggered, a high is provided to the anode of D16255 to trigger a
shutdown.
To determine if the 8 blinks is caused by the A board, SS board, or the Panel:
• Isolate the SS board and check if the TV stays on when it's turned on.
• If the TV does not stay on after disconnecting the SS board, the A board is
defective.
• If the TV stays on, then the SS or the Panel is defective.
• If the anode of D16280 (D280) is high (2.7V) at the time the unit shuts
down, the Panel might be defective. (Check for loose connection between the
flex-cables and the SS board).
• If the anode is low, the SS board is defective.
https://www.werbemousepads.de/pdf/