AC should not be applied at any time while adding resistors or unplugging connectors as damage to circuit boards might occur.
[A] The SMPS PWB 'Must' be producing STBY 5V on either pin 7,8,9 or 10 [5V]. If this voltage is not produced SMPS PWB is defective. There is no need to continue with next test.
[B] Unplug P700 on the main PWB and P203 to the ballast.
Add a 19K resistors between [5V Standby] pin 7,8,9 or 10 and pin-2 [PWR]. Apply AC. This will turn On the power supply.
- Check that the 24V and 12V power supplies are turned ON, P201 (24V pins 17 & 18) (12V Pins 13 & 14) and 24V to the Ballast P203 Pins 1-5.
- Remove AC Power. Reinsert the plug P203 to the ballast.
Continue if the above test is OK. Leave original 10K resistor in place.
- Add an other 10K resistor between 5V pin 7,8,9 or 10, and pin 20 [INV On]
Unplug the small ribbon connector CN-1. [This floats P-DIM].
- Apply AC power. This simulates a Power ON and Back light command.
- If back light is normal: If all is normal the back light should turn ON
- If back light is abnormal: Recheck connector P203 and confirm 24V on pins 105. If low, or missing , use diode mode to check the 24V line on Ballast connector CN 1. If low, this indicates a shorted output FET.
- If Open, check Ballast fuse, possible open.
- Confirm the INV On/Off line P203 pin-10 is going to 3V
- Confirm Pin-3 of CN-1 has >2V. If not, need to add 3V by adding a 10K resistor from 5V_ST to pin -3 of CN-1. Back light should light.
Remove AC power
- Check the connections to the back lights. 'Do Not' check with these when AC is applied as they can carry [1.2Kv each].
