Xo 4, Troubleshooting Manual

Page: 26 / 88

XO 4 & XO FLEX TROUBLE SHOOTING GUIDE
Version 3.30 26
“PROPORTIONAL VALVE”, AN-903:
Purpose:
The proportional valve controls the amount of water distributed to all instruments except the syringe.
The proportional valve is fully controlled by PWM pulse on a constant frequency of 78 kHz by the
“Power driver” AO-137 PCB on J5.
Spare parts for AN-903
3 Gasket MR-150
4 O-ring,12 x 1,5 B Viton SD-307
Green tube dental. FS-078
Failure description Reason Solution
No water on instruments. No water. Fault on waterline
(instrument bridge) Check if the water reaches the
syringe 3F/6F
The flow meter nozzle is
obstructed Replace the flow meters nozzle
(MG-608)
For more information, go to Page
23 “Flow meter”.
The “Power driver” is defect. Change “Power driver” AO-137
on page 21
The coil of the proportional valve
is defective Change the proportional valve
AN-903
The proportional valve is
obstructed Disassemble and clean the
proportional valve.
The flow meter is defective Change the “Flow meter”
AN-119
The AN-368 PCB is defective Change the “Bridge PCB AN-
368”.