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3. Checking the grid and filament voltages
Turn IG on with the tool program
and measure the grid and filament voltages (CP4[GRID],
CP5[FIL-], CP3[FIL+]). These voltages can also be measured at the IC bulb connector.
Check the grid.
Voltage across CP4[GRID] and IG bulb, Pin 4 = 15010±V
Pull out the IG connector if V
CP4
is abnormal. If V
CP4
becomes normal, replace the IG bulb.
If the voltage remains abnormal after the connector is disconnected, replace the IG CTRL-A
PCB.
Check the filament.
If the filament does not light, turn IG off and measure the resistance between Pin 3 and Pin 5
of the IG bulb. The resistance should not exceed 1Ω. Replace the IG bulb if the
resistance is abnormal.
If the filament does light:
Voltage across CP5[FIL-] and IG bulb, Pin 5 = 251±V
An abnormal V
CP5
value indicates an abnormal grid current. Replace the IG CTRL-A PCB.
If the filament is normal : Filament voltage (VCP3 – VCP5) = 3.0 to 4.0V
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