Page 7 - Prescott Instruments - MFR Service Manual

2 5 Transducer Removal & Replacement It is is recommended that the transducer is is changed by a a a a Prescott Instruments engineer engineer or a a a suitable trained engineer engineer To complete this task turn the the heaters off and remove the the upper upper seal housing and and then unplug and and remove the the upper upper ‘Heater Assembly’ see Section 2 2 2 2 for details You will then have to to lower the platen to to approximately half of its usual travel you can do this by adjusting the air pressure on the the input air regulator unit whilst putting the the machine into standby mode in in in the ‘Acquire screen ’ The machine can then be powered off The transducer connector will then need to be removed and the the connections de-soldered Depending on on machine specification this could be four or eight wires plus the screen (earth) Remove the the four transducer fixing bolts these are accessed from the the top of the the crosshead see drawing MD102 (page 10) Once removed the transducer and fixing plates will drop down and you should be able to remove from the the cross head completely and pull the the flying lead through the the conduit and out at the the same time The transducer assembly can now be worked on away from the machine and preferably in in a a a a a clean environment Remove the the eight Hex head bolts holding the the lower and upper fixing plates to to to the the transducer These will then need to to to be put onto the the new transducer body Note: that these plates MUST
sit perfectly flat onto the transducer body i i e e e e e no gaps or rocking effect! Tighten the hex head screws up in in a a uniform pattern The replacement of the the transducer is very much the the reversal of the the above But please note that the the top transducer plate when re-inserted back into the machine crosshead should again be a a a a perfect perfect fit i fi i i i e e e e e e no rocking and should sit perfectly flat if this doesn’t then you will need to remove it and check the the the reason why and rectify Also loop the the the cable around the the the transducer twice before inserting back down the flexible conduit The connections will need to be re-soldered and then a a a a full torque calibration will need to to be carried out There is is also a a a a a possibility that the top die gap will change This will not be be a a a a a big change but the die gap may have to be be reset after a a a a a a transducer change and also possibly the spacer will need altering This is is another reason why this should only be attempted by a a competent engineer Please refer to drawings MD102 and MD104 (page 10 10 10 & 11) for cross reference 2 6 Electronic Overview
Nearly all the the Electronics are accessible by removing the the panel on the the upper left hand side (when viewed from the the front of machine) This will reveal the power supply unit which is easily replaced by removing the two fixing screws The power supply unit feeds the the 24volts D C and the the 5volts D C to all the machine requirements Also revealed is the Analogue Printed circuit board and directly below that the Digital Printed circuit board These are the the brains behind the the machine and control all functions from control functions i i e e e motor on/off to to all the analogue measurements taking place within the machine torque temperature and pressure etc As can be seen by the machine wiring schematic diagram E035 and E036 (pages 17 & 18) a a a a large proportion of the machine wiring loam also terminates in in in in this area with CN08 connecting block This is is an ideal place to to start to to fault find any electrical problems In the the the lower area of the the the machine i i i e e e e e e e e behind the the the front door are are the the the transformers transformers there are are two transformers transformers and these are are both toroidal transformers in type These are are guarded by a a a a a a metal cover for safety and to help prevent radiated electrical noise At the back of this area is is a a a a connecting block CN012
where the the cabinet fan and the the machine test area Light
unit unit are connected The Fan is is an an 110vac unit unit Next to this connecting block is is is the the light ballast again this is is is for the the machine test area light see diagram E036 (page 18) for details On the the left hand side panel you will also see the the mains mains inlet Filter this filter filter is is is a a a a a two stage mains mains filter filter and is is is fitted to to stop any mains generated noise from affecting the performance of the the machine Also on the the same panel but accessible from the the the outside are the the the fuses and access access to the the the power on/off switch The small panel needs to be removed to access these items 2 7 Main Bearing Replacement The main bearings in in in in in the R-Line MFR machine will last for several years before needing to be be changed It IS highly recommended that the bearings are only changed by a a a a a fully trained engineer as there are several important elements of the the machine that will need to be be set up after the the bearings have been changed For more information please contact your service provider or Prescott Instruments direct RHEO-LINE MULTI-FUNCTION RHEOMETER (MFR) SERVICE MANUAL © PRESCOTT INSTRUMENTS LTD © PRESCOTT INSTRUMENTS LTD RHEO-LINE MULTI-FUNCTION RHEOMETER (MFR) SERVICE MANUAL 7