TV Micro IC8002 on the AGU board and Chimera Micro IC4100 on the B board monitor various switches, temperature sensors, and voltage lines to protect the unit. If a problem occurs in any of these areas, the TV Micro will turn the unit off and flash the power LED in a number of sets to indicate what caused the shutdown. Even if the Chimera Micro detects a problem, it communicates this to the TV Micro.
LAMP POSITION & LAMP COVER MONITOR
The T1 board contains a switch to monitor the lamp access cover. It is closed when the locking handle for the cover is turned fully clockwise to secure the door. This is necessary to assure proper airflow to cool the lamp. Note that the switch is in series with another located on the T2 board. This switch is closed when the lamp is fully seated into the high voltage cable connector in order to assure that no arcing occurs between the lamp pins and socket if the lamp were not pushed fully forward. This switch also completes the ground path for both switches keeping the lamp cover and lamp switch lines low. If either of the switches fails or is opened, the unit will shut down and the power LED will flash in sequences of 3.
THERMAL PROTECTION
The S2 board, located inside the lamp housing,
has a digital thermometer IC located on it. This IC sends temperature
information to the TV Micro via the 5V I²C bus. Fan speed is varied according
to the temperature feedback. If the temperature exceeds a pre-determined level,
the unit will shut down and the power LED will flash 2 times. The same thermal
IC is also located on the C board (not shown) to monitor the LCD panel
temperature and the HB board to monitor ambient temperature within the cabinet.
FAN PROTECTION
All 4 fans in the television are monitored for rotation. If
a fan is operating properly, the rotation protects line for each fan will be
less than 1VDC. If any of the fan protect lines rises above 1-volt, the unit
will shut down and flash the power LED 4 times.
LAMP & LAMP DRIVER PROTECTION
The Lamp Driver board (ballast) monitors the voltage and
current being sent to the lamp. When the lamp is fired from a cold start the
voltage can reach upwards of 26KV. Once the lamp starts and ionization of the
gas begins, the voltage is immediately dropped to around 20-30 volts and slowly
raised to an operating voltage of roughly 90 volts. During these sequences, the
current and voltage curves are monitored for abnormalities. A weak or defective
lamp can affect these curves as can a failure of the Lamp Driver circuits. Any
event in this stage will cause a high to appear at CN8410-7 which sends the
high to the B board via CN8003-8. The unit will shut down and flash the Lamp LED on the front
cover. The Lamp Driver is also
monitored to verify the proper startup of the high voltage circuit. If the Lamp
Driver fails to generate the required high voltage to start the lamp, the unit
will shut down and flash the power LED 5 times.
OVP & LVP PROTECTION
The regulated 12V generated on the GT board is
monitored at CN8401, pins 31 and 32. OVP and LVP circuits (consisting of zener
diodes and transistors), monitor this voltage. If the 12V line rises above
12VDC or drops below 8.2VDC the unit will shut down and flash the power LED 6 times
for a low-voltage condition or 8 times for a over-voltage problem. Q10.5V is monitored at CN8401 pins 45 and
46. If this voltage rises above 12VDC the unit will shut down and the power LED
will flash 10 times.
SPEAKER PROTECTION
If any DC voltage appears on the left or right
speaker lines, a high will enter the AGU board at CN8001-13. The unit will shut
down and the power LED will flash 7 times.
LED BLINKING CODES CHART
DIAGNOSTICS HISTORY
ALTERNATE DIAGNOSTICS HISTORY
A history of protect events can be viewed by turning the
unit off and re-starting by pressing the DISPLAY, 5, VOL-, and POWER buttons,
in sequence on the remote commander. A view of the above diagnostics features
will appear. If an event occurred of any of the protect circuits, a “1” will
appear in the extreme right hand column. A "0" will appear if no event occurred.
This feature is useful for troubleshooting intermittent problems or multiple
protect events of more than one item to assist in determining where the failure
might be occurring. The protect event column does not keep a running tally of
events. It will always show “1” when an event has occurred even if it has
happened more than once. The event
column can be reset back to zero by pressing the number “8” followed by “ENTER”
on the remote commander. This is not the same as pressing these keys to reset
the television as is done in the service mode.
ALTERNATE DIAGNOSTICS HISTORY
A history of diagnostic events can also be viewed in the
service mode. Power the unit down and press DISPLAY, 5, VOL+, and POWER, in sequence,
to enter the service mode. The firs Item adjustment group “STATUS_1” will appear.
By scrolling through these items all of the protect events mentioned will
appear. If an event occurred the data will have changed from zero to one. This
record will remain unless the data is set back to zero and saved. An additional set of status information is
available by continuing to scroll and located the “STATUS_2” items. If more
than one diagnostics event has occurred, the data will have changed from zero
to one.
