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TROUBLE SHOOTING TABLE
No backlight
The power LED is blinking in red in the microprocessor's
lamp error mode.
Get short-circuited the capacitors that are connected with
pin (22) of IC7301, IC7401, IC7501, IC7601, IC7701 and
IC7801 of the inverter units 1 thru 6. Turn on the AC power
of the set in the
Check for a lighting-failure inverter unit. Turn off the power
within 3 seconds.
Is the voltage being supplied to the inverters at 24V?
(P7310, P7510, P7407, P7607, P7711, P7811)
YES
Are there voltages of over 2.5 V at pins (1) (DUTY) and (16)
(STB) of IC7301, IC7401, IC7501, IC7601, IC7701 and
IC7801?
YES
Is there the output voltage of 8.5V at IC7302, IC7402,
IC7502, IC7602, IC7702 and IC7802?
YES
Are there startup voltages at the terminals COMP1,
COMP2, VS1-2 and IS1-2 of IC7301, IC7401, IC7501,
IC7601, IC7701 and IC7801?
YES
Check the peripheral circuits of IC7301, IC7303, IC7401,
IC7403, IC7501, IC7503, IC7601, IC7603, IC7701, IC7703,
IC7801 and IC7803.
* The inverter is giving out the ERR signal.
Output conditions: Have the following to keep the SPC terminal voltage at over 2.2V.
VS terminal > 1.25V
IS terminal < 0.6V
COMP terminal < 0.6V
COMP terminal > 1.25V
Check the output voltages of the power unit.
NO
Keep the connectors open and check the voltages. Are they
all at 24V?
Check the input-side parts of the transformers T7301 thru
T7306, T7401 thru T7406, T7501 thru T7506, T7601 thru
T7606, T7701 thru T7706, and T7801 thru T7806.
Check all the connectors for tightness. (P7308, P7309,
NO
P7508, P7509, P7408, SC7401, P7608, SC7601, SC7701,
SC7801)
Check the peripheral circuits of IC7301, IC7401, IC7501,
NO
IC7601, IC7701 and IC7801.
Check the connections of P7301 thru P7306, P7401 thru
NO
P7406, P7501 thru P7506, P7601 thru P7606, P7701 thru
P7706 and P7801 thru P7806.
Check the output-side diodes and their peripheral parts of
T7301 thru T7306, T7401 thru T7406, T7501 thru T7506,
and T7601 thru T7606.
49
(Continued)
NO
YES
LC-65D90U
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