Wednesday, February 10, 2016

How to enter service mode Panasonic Plasma TV - PANASONIC PLASMA TV - TC-P50ST50 - TC-P50UT50 – LED Blinking and causes - Detailed troubleshooting for power led blinking - Plasma television repair and service

Category: Plasma Television Repair and Service 

Contents of this article 

  • LED Blinking and possible causes
  • Detailed Troubleshooting procedure  




PANASONIC TC-P50ST50 - TC-P50UT50

When an abnormality occurs in the unit, the “SOS Detect” circuit is triggered and the TV shuts down. The power LED on the front panel will flash a pattern indicating the circuit that has failed.
If the power LED continues to blink even after the TV is unplugged, press and hold the power switch on the TV for a few seconds until the LED turns off. Some steps require removal of connectors and sometimes PC boards removal. Do not allow the TV to
 un for more than 30 seconds while connectors or boards are disconnected.
NOTE: When taking voltage reading, place your meter’s probe on the test point or pin indicated before connecting the TV to the AC line. The voltage you intent to measure may only appear for a brief moment.
Warning: The Vsus line has large capacitors that hold the charge for some time even after the TV has been turned off and unplugged. When disconnecting P2/SC2 or P11/SS1, bleed the remaining charge of the Vsus before reconnecting the cable. Use a 500 ohms/ 5W (At least) resistor to discharge the Vsus line before reconnecting P2/SC2 or P11/SS11.
LED BLINKING AND POSSIBLE CAUSES
1 BLINK
Panel Information
SOS Communication problem
2 BLINKS
P15V form the P board
Missing P15V
P15V is not been generated by the P board. Wrong diagnostic by the A board
3 BLINKS
Incomplete or interrupted
Boot Program execution of PEAKS IC (IC8000).
Shorted P15V
Missing F15V Wrong diagnostic by the A board
4 BLINKS
Power Supply output voltages
Vsus Over Voltage Condition.
P15V Shorted while in operation. Wrong diagnostic by the A board.
6 BLINKS
SC Energy Recovery Circuit
An increase or reduction of the Energy Recovery Circuit output (MID).
Shorted SUB5V.
Wrong diagnostic by the A board.
7 BLINKS
Scan Drive Circuit and Connection between the SC board and the SC board.
Missing or shorted Vsus.
Abnormality of the scan circuit output, the 15V_F, the scn_pro, and Vscn circuit.
Loose or open Connection between the SC board and the SC board (SC41, SC42, SC46).
Open or loose connection between connectors SC2/P2
Wrong diagnostic by the A board
Defective panel
8 BLINKS
Sustain Drive Circuit and Connection between the SS board and the Panel.
Abnormality of the sustain drive circuit.
Open or loose connection between the SS/SS2 Boards. and FPCs from the panel (SS52 – SS54 – SS55 – SS57).
Open or loose connection between connectors C10/C20 or C26/C36.
Wrong diagnostic by the A board.
9 BLINKS
Discharge Control Circuit DDC (IC9300)
Failure of IC9300
Wrong diagnostic by the A board.
10 BLINKS
SUB3.3V_Sense (OVP)
Over Voltage Condition of SUB5V or SUB3.3V
Wrong diagnostic by the A board
12 BLINKS
Audio Amp. Circuit
Defective Speaker/Subwoofer
Pinched Speaker Wire
Wrong diagnostic by the A board.
13 BLINKS
IC8000 Internal
Communication Defective A board
DETAILED  TROUBLESHOOTING PROCEDURE
Troubleshooting 2 Blinks Failure (TC-P50ST50)
Place the positive lead of a voltmeter at pin 13 of connector P6 while the black lead is connected to ground (Chassis ground). Plug in the TV and turn it on.
Does 15V appears momentarily on pin13 of CN P6?
If not Replace the P board
If yes Replace the A board
Troubleshooting 2 Blinks Failure (TC-P50UT50)
Place the positive lead of a voltmeter at pin 13 of connector P6 while the black lead is connected to ground (Chassis ground). Plug in the TV and turn it on.
Does 15V appears momentarily on pin13 of CN P6?
If not Replace the P board.
If yes Unplug the TV. Check the resistance between TP201 (P3.3V) on the C2 board and chassis ground.
Is there a short circuit? The Defective Panel and/or C2 board.
If not Replace the A board.
Troubleshooting 3 Fast Blinks Failure (TC-P50ST50)
Unplug the TV. Check for short circuit or low resistance between pin 13 of connector P6 and ground (Chassis ground).
Is there a short circuit or a resistance lower than 1 Kilo-ohm?
If not then Replace the A board
If yes the check the flowing
With the TV still disconnected, remove connector A6 from the A board and perform the same resistance check on pin 13 of connector P6.
Is there a short circuit or a resistance lower than 1 Kilo-ohm?
If yes then Replace the P board
If not  Reconnect A6 and remove connector SC20 from the SC board and check for short circuit or low resistance on pin 13 of connector P6.
Is there a short circuit or a resistance lower than 1 Kilo-ohm?
If not Replace the SC board
If yes check the following
Reconnect SC20 and remove connector SS33 from the SS board and check for short circuit or low resistance on pin 13 of connector P6.
Is there a short circuit or a resistance lower than 1 Kilo-ohm?
If not then replace the SS board
If yes the check the following
Reconnect SS33 and remove connector A31 and A32 from the A board and check for short circuit or low resistance on pin 13 of connector P6.
Is there a short circuit or a resistance lower than 1 Kilo-ohm?
If yes the Replace the A board
If not If no short circuit is found on any of the C boards, change the panel
Troubleshooting 3 Fast Blinks Failure At Plug-in (TC-P50UT50)
Unplug the TV. Connect the negative (Black lead) of your DC volt- meter on chassis ground. Place the positive lead of on pin 10 of connector P6 on the power supply. While observing the display on your meter, plug-in the TV.
Does 15V appear briefly?
If not Replace the P board,
If yes then check the following
Unplug the TV and remove connector K1 from the A board. Plug in the TV and press the power switch on the TV.
Does the TV turn on and stays on?
If yes Replace the K board
If not then check the following
Unplug the TV and reconnect K1. Disconnect connectors A31 and A32 from the A board. Plug-in the TV.
Is the power LED blinking 3 or 8 times?
If 3 times then Replace the A board
If 8 Times then Defective Panel or/and the C3 board. To time it takes to isolate the C3 board from th panel is approx. 30 minutes. To isolate the C3 board, reconnect A31 and A3 and remove the metal bracket over the C boards. Disconnect connectors CB12~CB15 from the C3 board and plug-in the TV. If the power LED stops blinking at plug-in, then the Panel is defective. If the LED blinks 3 times, then the C3 board is defective.
Troubleshooting 4 Blinks Failure
Place the positive lead of a voltmeter at pin 4 of connector P6 while the black lead is connected to ground (Chassis ground). Plug in the TV and turn it on
Is there 2V to 3V (Approx.) momentarily on pin 4 of CN P6?
If not Replace the A board
If yes then Replace the P board
Troubleshooting 6 Blinks Failure
Verify that all the cables on the SC board are properly seated. Also check the ribbon cables and connectors on the A and C boards. Unplug the TV and disconnect connector SC20 on the SC board. Plug in the TV and turn it on.
Did the number of blinks change to 8 blinks?
If not then Replace the A board
If yes replace the SC board
Troubleshooting 7 Blinks (SOS 7)
A 7 blinks shutdown can be caused by a failure of any or a combination of the following boards: SU/SD, SC, A, or the Panel. Is also possible for the SS board to cause 7 blinks shutdown on this model.

Troubleshooting 7 Blinks Failure (TC-P50ST50)
Check the wires between connector P2 on the P board and SC2 on the SC board. Make sure they are properly seated. If the problem persists, unplug the TV and remove connector SS11 from the SS board. Plug-in the TV and turn it on.
Is the power LED blinking 7 or 8 times?
If 8 Times then Replace the SS board
If 7 Times then check the following
Unplug the TV and reconnect SS11. Remove SC20 from the SC board. Plug-in the TV and turn it on.
Is the power LED blinking 7 or 8 times?
If 7 Times then Replace the A board
If 8 Times then Unplug the TV. Reconnect SC20 and check the following .
1.Using any of the VFG screws (Floating ground screws) as ground, measure the resistance of pin 2 and pin 6 of either SU41/SC41or SD42/SC42. If a short circuit is found, proceed with step 2. If no short circuit is found, isolate the SU and SD boards as illustrated on the next slide.
2.Unplug SU41 and SD42. Using any of the VFG Screws (Floating ground screws) as ground, measure the resistance of pin 2 and pin 6 of bothSU41 and SD42.
A short circuit indicates the failure of the board where it was found.
Note: Change the SU and SD boars together even if only one is found to be defective.
Is there a short circuit?
If yes Unplug the TV and follow step 2 of the previous slide.
Is there still a short circuit?
If not Replace the SC board
If yes then SU/SD are Defective. To find out if the SC board is also defective, follow the procedure to on the next slide to isolate the SU and SD boards. Plug in the TV and press the power switch.
Does the TV turn on and stay on ? (Black screen)
If yes Replace both the SU and SD boards
If not Replace the SC, SU, and SD boards
Troubleshooting 8 Blinks Failure (TC-P50ST50)
Check all the cables between the SS/SS2 boards (SS52, SS54 ~SS57) and the panel. Make sure they are properly seated in the connectors. Unplug the TV and disconnect SS33 on the SS board. Plug in the TV and turn it on.
Does the TV turn on and stay on?
If 6 or 8 blinks then , If all connections between the SS/SS2 boards are confirmed OK, replace the A board
If yes then Unplug the TV. Check for continuity between pins 1 and 2 of connector SS52 on the SS board. Do not plug in the TV.
Is continuity ok?
If not Check connections between the SS board and the panel. Check also connections between the SS2 and the SS board and the panel. If ok, then replace the panel
If yes then Check for continuity between pins 1 and 2 of connectors SS54 ~SS57on the SS2 board. Do not plug in the TV.
Is continuity ok in all the connectors?
If yes then Replace the SS2 board
Troubleshooting 12 Blinks Failure
Unplug the TV and remove connector A12 from the A board. Plug in the TV and turn it on
Is the TV still shutting down with 12 blinks?
If yes the Replace the A board.
If not Disconnect the speakers one at a time to determine which one is bad.