Table of Contents
Advertisement
1. Open the shield on the ballast assembly and locate connector B2/pin 1.
2. Using any shield as cold ground, monitor the voltage at B2/pin 1.
3. Turn on the TV. The B2/pin 1 voltage from the microprocessor should be
3Vdc at turn-on. If 3V is not present, the DG board is suspected. If 3V is
present, the microprocessor input to the ballast is OK and go to step 4.
4. Verify 330Vdc from the power supply by measuring between B1/pins 1 & 3 at
the ballast before the TV shuts down. (You may turn the TV back on again to
measure this voltage.)
If the voltages noted in steps 3 & 4 are both present, and the Z001 spark gap did
not spark, the microprocessor (DG Bd.) and power supply (P Bd.) are working
properly but the ballast is likely defective. Replace or repair the ballast.
b) Refer to figure 23. Observe the lights on the L board to see if the microprocessor
is initiating a lamp-on signal.
When the microprocessor (DG board) outputs a high to turn on the ballast (B2/pin
1), it also outputs a high (L5/pin 9) to turn on the lamp enable LED on the L board.
Therefore if the second (2) LED is lit, the ballast-on signal is assumed to have been
generated by the microprocessor.
L Board LED Indicators
There are internal LED indicator lights on the L board (left of the ballast assembly).
During power on (warm-up), they show the microprocessor outputs concerning the
ballast / lamp operation. During warm-up, the LEDs light in the following sequence
and indicate the following condition.
1. Power Good – Power supply (3.3Vdc) voltage detected by the microprocessor.
2. Lamp Enable – Ballast-on signal sent from the microprocessor to the ballast.
3. Clock – L Board LVDS IC6001 video clock. IC6001 is getting power since the
IC6001 internal clock is active as soon as the IC receives power.
4. Lamp Lit – After the ballast tells the microprocessor that the lamp is drawing
current, the microprocessor turns on the fourth LED to indicate that the
microprocessor will not start the lamp failure shut down sequence.
Figure 23 - L Board LED Indicators
29
Advertisement
Table of Contents
