Malfunction Fan Control board or SMPS board.

Measure on the Signal Backplane the +24V voltage on pin 9, 10, 11 or 12 of the connector of the black wire unit which comes from the SMPS board. See image.

If the measured voltage is about 24V then replace the Fan Control board. See "Removing a board in the card cage". Otherwise replace the SMPS board. See"Replacement of the Switched Mode Power Supply".

Damaged insulation of the wire unit (reference 1 image "Cathode fan connections") of the Cathode fan (reference 3 image "Cathode fan connections").

To Check the insulation of the wire unit of the Cathode fan, pull out the wire unit (reference 1 image "Cathode fan connections"). The Cathode fan is located at the right inner side of the Lamp compartment.

1. Repair the insulation of the wire unit using shrink sleeve.

2. If not repairable replace the Cathode fan. See "Lamp cathode fan".

Malfunction Signal Backplane (bad connection)

Replace the Signal Backplane. See "Replacement of the signal back plane".