Fisher & Paykel MR720 User Manual
iv
Ref. 185040646 *MR730/720/700/480 Technical Manual ¯ Revision F ¯ Issued March 2001
4.0 CIRCUIT OPERATION .........................................................................................................................9
4.1
Introduction......................................................................................................................................................................................9
4.2
Control Board..................................................................................................................................................................................9
4.2.1
4.2.1
Control Thermistors ......................................................................................................................................................... 9
4.2.2
Input Analog Switches U8 and U9................................................................................................................................ 9
4.2.3
Analog to Digital Converter U10 b,d,e.......................................................................................................................... 9
4.2.4
Processor Control U3....................................................................................................................................................... 9
4.2.5
Power Line Interrupt (Revisions D/F PCBs)............................................................................................................... 10
4.2.6
Power Line Interrupt (Revision H PCB and later)...................................................................................................... 10
4.2.7
41 °C Comparator............................................................................................................................................................ 10
4.2.8
Heaterplate Overtemperature........................................................................................................................................ 10
4.2.9
Watch Dog ...................................................................................................................................................................... 10
4.3
Power Board...................................................................................................................................................................................11
4.3.1
4.3.1
Revision D/F PCBs ......................................................................................................................................................... 11
4.3.2
Revision H AND J PCBs ............................................................................................................................................... 11
4.4
Probe Temperature versus Thermistor Resistance...............................................................................................................11
5.0 CALIBRATION ....................................................................................................................................12
5.1
Introduction....................................................................................................................................................................................12
5.2
Equipment Required......................................................................................................................................................................12
5.3
Calibration Procedure for Models with Revision D PCBs or earlier..................................................................................12
5.4
Calibration Procedure for Models with Revision F PCBs or later ......................................................................................12
6.0 PERFORMANCE CHECK ..................................................................................................................14
6.1
Introduction....................................................................................................................................................................................14
6.2
Performance Check MR730/720/700 ......................................................................................................................................14
6.2.1
6.2.1
Equipment Setup Notes:................................................................................................................................................ 14
6.2.2
Setup ................................................................................................................................................................................ 14
6.2.3
Temperature Control Check MR700/720/730.............................................................................................................. 14
6.2.4
Alarms check MR700/720/730 ...................................................................................................................................... 15
6.3
Performance Check (MR480)....................................................................................................................................................15
6.3.1
6.3.1
Equipment Required....................................................................................................................................................... 15
6.3.2
Setup ................................................................................................................................................................................ 15
6.3.3
Temperature Control Check (MR480).......................................................................................................................... 15
6.3.4
Alarms check - MR480................................................................................................................................................... 16
6.4
Dual Probe Temperature Test....................................................................................................................................................16
6.4.1
6.4.1
Equipment Required....................................................................................................................................................... 16
6.4.2
Test Procedure................................................................................................................................................................ 16
7.0 SERVICING INFORMATION............................................................................................................17
7.1
Introduction....................................................................................................................................................................................17
7.2
Printed Circuit Board Removal ..................................................................................................................................................17
7.2.1
7.2.1
Control PCB..................................................................................................................................................................... 17
7.2.2
Power PCB....................................................................................................................................................................... 17
7.3
COMPATABILITY.......................................................................................................................................................................17
7.3.1
7.3.1
Hardware compatability................................................................................................................................................. 17
7.3.2
MR480 Transformers ..................................................................................................................................................... 18
7.3.3
Software compatability.................................................................................................................................................. 18
7.4
Heaterplate .....................................................................................................................................................................................18
7.4.1
7.4.1
Heaterplates with screw-in standoffs.......................................................................................................................... 19
7.5
Fault Location ................................................................................................................................................................................19
7.6
Screw Torque Settings.................................................................................................................................................................19