Panasonic TH-42PZ800U Service Manual page 131

Subject: Isolation of SU and SD boards from the SC board.
Symptoms such as shutdown followed by a 7-blink code may be
Purpose:
caused by a circuit failure located on any of the SU, SD, or SC
boards. This procedure helps pinpoint the location of the failed-
board.
Models: TH-42PX80U, TH-50PX80U, TH-42PZ80U, TH-46PZ80U, TH-
50PZ80U, TH-42PZ85U, TH-46PZ85U, TH-50PZ85U, TH-
42PZ800U, TH-46PZ800U
Not yet confirmed in TH-50PZ800U, TH-58PZ800U, TH-
46PZ850U, TH-50PZ850U, TH-58PZ850U, and TH-65PZ850U.
Note: Unlike previous models of Panasonic Plasma TVs, the 2008
models listed above are designed not to turn-on if either of the
SU and SD boards is disconnected. Disconnecting either causes
the unit to shutdown and the power LED to blink 7 times.
Unplugging any of the connectors SC41/SU41, SU11/SD11, and
SC42/SD42, opens the interlocked connection between
VF_GND and CHA on the SC board. This floats point CHA,
triggering shutdown, refer to figures 1 and 2.
SU/SD Board Isolation