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Ref. 185040646 MR730/720/700/480 Technical Manual ¯ Revision F ¯ Issued March 2001
7.4.1 HEATERPLATES WITH SCREW-IN STANDOFFS
For products after S/N:9773XXX19731, the heaterplate standoffs were changed to shoulder bolts that screwed directly
into the heaterplate.
When fitting these heaterplates,‘click’ the heaterplate springs into the recesses on the heaterplate (by rotating them
while pushing down), then align the springs with the holes in the case front and screw in the self tapping standoffs into
the heaterplate.
7.5 FAULT LOCATION
If neither the digital display nor any of the front panel LED’s are on and no power appears to be reaching the
transformer primary, check that the mechanical overheat protector on the heaterplate has not cut out. This may be
checked by depressing the red reset button. (See § 7.4).
Determine if all power supplies are operational and all fuses are intact. If the power supplies are OK but the display is
blank, check the watch dog output (pin 12, U5g). A high output here will blank the display, turn on the humidifier fault
LED indicator and isolate the heater circuits but not necessarily stop the processor. Check for the presence of a 33 to 40
ms period square wave at PB7 (pin 1 U5b). If the watch dog output is high and the 33 to 40 ms clock is present a fault in
the watch dog circuitry is indicated but if port PB7 is not changing state there is a fault elsewhere.
7.6 SCREW TORQUE SETTINGS
Below is a guide to screw torques used on the humidifier, use this as a guide for tightening of screws on the humidifier
(exact torques are not required).
Ref Screw Application Driver Torque(in/oz) Torque
(Nm)
CHASSIS
14 Screw #8 x ½" Pan Phil TY25 S/S Case Front/Body Phillips 85-113 0.6 to
0.8
18 Screw M4 x 8 Pan Phil Taptite Chassis Earth Screws Phillips 240-270 1.7 to
1.9
21 Screw M6 x 25 Csk Allen S/S Mounting Bracket Allen 248-276 1.75 to
1.95
22 Screw M4 x 14 Pan Pozi Taptite Mains Cord Clamp Pozidriv
e
198-240 1.4 to
1.7
26 Screw M6 x 16 Allen S/S Button
Head
Chassis Earth Screw Allen 248-276 1.75 to
1.95
27 Screw M3 x 5 Pan Phil Taptite Heaterplate Standoffs Phillips 99-113 0.7 to
0.8
HEATERPLATE
2 Screw M4 x 8 Pan Phil Taptite Heaterplate
Earth/Element
Phillips 212-254 1.5 to
1.8
5 Screw M3 x 5 Pan Phil Taptite Thermistor/Thermostat
Heaterplate
Phillips 99-113 0.7to 0.8