Model 8013 Electropneumatic Positioner with Cam Instructions

Transcription

1 Model 8013 Electropneumatic Positioner with Cam Instructions Instruction No E Mounted on Series 37 / 38 Spring Diaphragm Actuators (Only for valve strokes 1 1/2 to 4 ) Preliminary steps 1. Unpack carefully. 2. Read instructions before mounting. 3. Record serial number for future reference. 4. The positioner is fitted with a powerful magnet: do not bring close to it a watch or an instrument likely to deviate under the influence of a magnetic field. Introduction These instructions apply to installation, adjustments, calibration and eventual repair of 8013 Series Positioners with cam, mounted on Series 37/38 Spring Diaphragm Actuators. This version of the Positioner can be manufactured to meet the requirements of each standard pertaining to: protection against explosion for equipment intended to be installed in an hazardous atmosphere; protection against dust and against water-splash for tight equipment; sometimes a combination of the two preceding protections. The instructions pertaining to these standards as well as to electric characteristics of the positioner are further explained in a supplementary Instruction No ES E. In all instances the operator should therefore be in possession of the supplementary Instruction No ES E in addition to this instruction. Caution This equipment should not be installed, kept up or put into operation without having read and fully understood before-hand the instructions contained in this instruction and in the supplementary No ES E. Moreover, before initiating any operation on this positioner the following should be read: a) operating instructions pertaining particularly to installation. b) safety rules listed on the instruction plate attached to the cover of the device in certain cases (positioners with explosion-proof housing). C) In case of flameproof housing device, the positioner case must not be opened when the device is energized. Non compliance with these rules and caution notes of this instruction may bring about faulty operation of the device, interfere with the installation or damage it seriously. In addition such negligence might expose operating personnel present on the site to grave hazards. After sales department has a highly skilled After Sales Department available for start-up maintenance and repair of our valves and components parts. Contact the nearest Sales Office or representative or directly the After Sales Department of CONDÉ-SUR- NOIREAU Plant. Any future orders for spare parts should be addressed to the Spare-Parts Department of our factory at CONDÉ- SUR-NOIREAU. When such an order is placed you should always cite in reference the original order and, in particular, the type and the serial number of the positioners involved. Training MASONEILAN regularly holds training seminars for technicians in its factory of CONDE-SUR-NOIREAU. In order to attend one of these training seminars you should get in touch with our local representative or our Training Department.

2 description and operation General The positioner is an electropneumatic force-balance device which provides an accurate means of obtaining at any time a valve stem position corresponding to a theoretical position envisaged for a D. C input signal. In addition, the positioner provides a convenient means of split-ranging operation for two valves from a single signal emitted by a single controller. The positioner may have either direct or reverse action on either direct or reverse actuators (Air-to-close or Airto-open). The feedback device of this positioner is fitted with a double lobe cam permitting the valve on which it is installed to present either the Linear or Equal percentage flow characteristic. It is only necessary to change the cam position. Operation Direct action With direct positioner action, an increase in the electric input signal produces a force on the beam moving the flapper to cover the nozzle. The increase in nozzle back pressure increases positioner output pressure to the actuator. The resultant actuator stem motion is transmitted to the force-balance spring, extending the spring until the force exerted on the beam balances the opposing force of the coil. As these two forces equalize, nozzle back pressure decreases. The system then is balanced and positioner output pressure is stabilized at an amount necessary to maintain the valve plug in the desired position corresponding to the input signal value. The cam profile designed for the required flow characteristic interferes in this conversion process of a signal into movement. Reverse action With reverse positioner action, an increase in the electric input signal produces a decrease in output pressure. Changing of positioner action a) Consult the Instruction No ES E. b) Reverse the positions of the coil leads on the terminal board (see Instruction No ES E, page 3). c) In case of intrinsically safe circuit, replace the coil by another one corresponding to the new action (Instruction No ES E, page 3). d) Reverse the force balance spring position in regard to the beam (see corresponding paragraph of page 4. e) In case of flameproof housing device, the positioner case must not be opened when the device is energized. f) Calibrate after changing of action. split-range operation Split-ranging permits the operation of two valves in sequence from one control instrument signal. The total actuator stroking of each valve occurs with one half the signal. The following instructions apply only when the positioners are mounted according to the diagram opposite (connection in series). The total circuit resistance of positioners installed for split-range operation must be in accordance with the total load requirement of the controller. In this case, the total resistance of the circuit is double of the one of a positioner. Also the features of these positioners are a force balance spring which exerts a force equal to half of the one exerted by the standard spring. To calibrate a positioner for split-ranging operation, proceed as indicated in chapter Calibration considering that the connection of the controller on each positioner is performed as indicated in the Figure 1. The opposite table shows as an example, the plug positions of two split-ranging valves opening on air failure with a 4-20mA signal. On request, supplies the data required for the selection of the equipment or for its modification in the field. CONTROLLER Controller output signal Figure 1 Plug position for first valve POSITIONER No 1 POSITIONER No 2 Plug position for second valve 4 ma Full open Full open 8 ma Intermediate 12 ma Closed 16 ma Intermediate 20 ma Closed 2

3 installation Warning De-energize electric and pneumatic circuits before service or maintenance. e sure that connections are correctly performed and that the cover is well placed on the case before energizing the circuits. Only qualified personnel to service this equipment. CHECKINGS efore installing the positioner on the actuator of the valve, the following should be checked : Proper mounting of the cam (87) and back lever (261) assembly, (see below). Correct position of the force balance spring (8), (see page 4). Proper nozzle number (16), (see trouble shooting ), Proper coil S/A (40) and terminal board S/A (15) (see Instruction No ES E). GENERAL 8013 Series Cam Positioner are mounted on control valves with the following characteristics: Opening on air failure by air-to-extend actuator stem (type 37). Closing on air failure either by : air-to-retract actuator stem (type 38). air-to-extend actuator stem (type 37) in case of valves whose plug is located under seat-ring (s). INSTALLATION Location Avoid locations which are subject to wide ambient temperature variations. If control valve is subject to sub-freezing temperature, special provisions must be made for drying positioner air supply. Vibrations: If possible, avoid locations where vibrations occurs. Positioner action The positioner can operate either by direct action (increasing instrument signal produces an increase in output pressure) or reverse action (increasing instrument signal produces a decrease in output pressure). The choice of valve-actuator-positioner actions depends on the desired final action for the signal (open or close) and/ or safety action (open or close on air failure, for example). Positioners fitted on control valves are factory mounted on actuator and according to the desired action specified by the customer. If it is necessary to disassemble the positioner, if a different action is desired or if a positioner must be mounted on a valve already installed, proceed with installation in the sequence shown in this chapter. Position & mounting of feedback elements The feedback elements of the positioner include cam (87), back lever (261) and force-balance spring (8). Position of cam (87) and back lever (261) The cam and back lever are a subassembly unit which oscillates around an integrated bearing post (80) located at the back of the case. 1. The back lever (261) is always mounted on the left of the positioner when this one is seen from the rear, (see Figure 2). 2. The ref. (LIN or PERC) which appears on the front of the mounted cam (87), must agree with the chosen flow characteristics (linear or equal percentage). Also, this ref. must indicate the rotation axis of the cam (see Figures 2 & 3). If one of these conditions is not applied, proceed as follows : LINEAR OPERATION EQUAL PERCENTAGE OPERATION LIN. LIN PERC PERC. Figure 2 Position of cam (87) and back lever (261) (rear view of positioner) Figure 3 Mounting cam and back lever 3

4 On Air-to-Extend Actuator Stem (Type 37) On Air-to-Retract Actuator Stem (Type 38) A A Figure 4 Force-balance Spring Position (8) a) Remove retaining-clip (91) and disengage cam (87) - back lever (261) assembly from the bearing post (80). Unscrew the nut (90) and disassemble cam and back lever. Apply a few of grease such as ardahl (or equivalent) on the bearing post (80). b) Reassemble cam and lever in the proper position and tighten firmly nut (90). Replace this subassembly on bearing post (80) being careful to place correctly the bearing-lever (82) relating to the cam (87) and the lever (32). Replace the retaining clip (91) (see Figures 2, 3 and 10). Force-balance spring position (Figure 4) The position of force balance spring (8) regarding to the beam (41) is function of the actuator action (Air-to-Retract or Air-to-Extend actuator stem): On Air-to-Extend actuator stem (Type 37), the hooking head of adjusting screw (6) is located under the beam (41) and screw (12) is in lower square hole () of inside lever (10). On Air-to-Retract actuator stem (Type 38), the hooking head of adjusting screw (6) is located above the beam (41) and screw (12) is in upper square hole (A) of inside lever (10). If it was necessary to disassemble, proceed as follows during reassembly. 1. Insert screw (12) in the proper square hole (A or ) of the spring lever (10). The hole used to hook the spring and which is drilled in the screw head (12) must be perpendicular to the bottom of the case. 2. Adjust screw (12) on the spring lever (10) around the half of its length, tighten the two nuts (11) and hook the force-balance spring (8) Screw adjusting screw (6) on the proper side of beam (41). e careful to have the nut (7) always placed on top of beam for easy reaching. 4. If the entire operating mechanism has been removed from the positioner, place it into the case without tightening its mounting screws (4). Position the entire operating mechanism in a way to center flapper (46) above the nozzle (16) inlet. Tighten the two mounting screws (4). 5. Connect the two wires of coil (40) to the terminal board (15) and couple the force-balance spring (8) onto the adjusting screw (6). Proceed with calibration. Close to cover. Electr. signal connection: cable gland DIA. 3 to 9 mm Air supply: connection 1/4 NPT Figure 5 Mounting on Types 37/38 Spring Diaphragm Actuators

5 racket (22) Actuator axis POSITION OF HOLE A1 FOR ALL ACTUATOR STROKES 1 1/ /4 21/2 31/2 3 4 A2 A1 ack lever (261) 8013 Outline (Front View) Oblong hole common to all actuator strokes (for screw A2) L A Position of mounting screws (268) of bracket (22) on the actuator yoke, according to actuator stroke (example for a 4 stroke) Mounting screws (29) of 8013 on the bracket (22) Actuator (mm) Stroke (in.) L Dimension (mm) 38, /2 53,1 50, ,8 57, /4 79,7 63, /2 88,6 76, , /2 101,6 4 1 /2 106,3 124,0 141,7 Figure 6 racket (22) and ack Lever (261) Posibilities (Front View) MOUNTING OF THE CASE S/A Fastening (Figures 5,6 & 10) The cam positioner 8013 is fastened on the actuator yoke by means of a mounting bracket (22), and five Hex. head screws (29 & 268). The position of the mounting bracket (22) on positioner case is always the same, whatever the actuator action. The selection of holes to be used to secure bracket (22) on the actuator, vary according to valve stroke. After installation of cam and back lever or after checking their correct position, secure mounting bracket (22) at the back of positioner by means of three Hex. head screws (29) ( holes). Install this assembly on actuator yoke by means of two Hex. head screws (268) and two washers (269). ( A holes). First, select the hole (A1) of the screw (268) according to actuator stroke, then place the second screw in the (A2) position through the oblong hole of bracket (22). Refer to Figures 5 and 6 to install mounting bracket (22). Caution: The bracket (22) agrees to the most used strokes of the valves, choosing the appropriate fastening holes. Each back lever (261) has an appropriate length to only one valve stroke (1 1 /2 to 4 ). It must be changed if the stroke is modified or if the positioner is installed on another valve that specified one. 5 Linkage assembly (Figure 7) They include clevis (262), turnbuckle (263), turnbuckle screw (265) transmission rod (266) and locknut (264). The transmission rod (266) is fitted by threading on the actuator coupling in cases of Nos 15, 18 & 24 actuator sizes. If Nos 9, 11 & 13 actuator sizes, the transmission rod is firmly secured on actuator stem by means of a take-off clamp and two clamp screws. Proceed with installation as follows: After securing the instrument on yoke, solidly screw the transmission rod (266) into the tapped hole of the actuator coupling, or fasten the take-off clamp, including the transmission rod, on the actuator stem, (only on actuators Nos 9, 11 & 13), (see Figure 7). Note: The take-off clamp must be attached to the actuator stem at a point permitting the full actuator stem travel. Adapt clevis (262) on back lever end (261) by means of clevis pin (253), washer (254) and retaining clip (255). Screw turnbuckle screw (265) on threaded end of transmission rod (266) and rotate it until it aligns with the clevis (rotation plane of back lever). Fully screw nut (264) on turnbuckle screw (265). Connect clevis (262) to turnbuckle screw (265) by means of turnbuckle, screwing them on the same length approximately. Note: The lower end of the turnbuckle hex has been machined round to identify the right hand thread which engages the turnbuckle screw (265).

6 ack lever (261) Washer (254) Retaining clip (255) Clevis (262) (left hand thread) Turnbuckle (263) Nut (264) Turbuckle screw (265) (right hand thread) TRANSMISSION ROD FASTENING ON Nos 15, 18 & 24 ACTUATORS TRANSMISSION ROD FASTENING ON Nos 9, 11 & 13 ACTUATORS Clevis pin (253) Transmission rod (266) Valve plug stem Transmission rod (266) Actuator coupling Valve plug stem Take-off clamp Top view Figure 7 Linkage Accessories Actuator stem Actuator stem PNEUMATIC CIRCUIT The positioner output and supply connections are tapped 1/4" NPT. They are located on the relay and marked with arrows. Standard pneumatic piping between the air filterregulator, positioner and actuator or other relay is 4 x 6 mm ( 1 /4 OD.) tubing, or 6 x 8 mm ( 3 /8 OD.) tubing on the largest actuators. Utilization of an air filter-regulator model 77-4 or is recommended on the supply circuit. e sure that its mounting position is correct, (drain-cock and dripwell downward). For the supply of the air filter-regulator, use 1 /4 OD. tubing (4 x 6 mm Dia.). If air line exceeds approx. 7 m length (23 feet), preferably use 3 /8 OD. tubing (6 x 8 mm). The supply connection of the air filter-regulator model 77 is 1 /4 NPT. Adjust the output pressure of the air filter-regulator to the pressure indicated on serial plate of the actuator. Admissible maximum pressures on the positioner must be in accordance with the valve and the actuator on which it is mounted, as well as to the pressure drop. For the valves equipped with a type 37/38 actuator, these maximum pressures are indicated in the valve catalog. The supply and connecting circuits must be perfectly sealed. NOTE: Relay may be mounted in any one of four position 90 apart but, on this configuration, the better orientation is with the connections located at the back. To change its position, disconnect air lines, remove the four mounting screws, establish the new desired relay position, replace the four screws and tighten them. Connect air lines. ELECTRICAL CIRCUIT See instruction sheet No ES E. calibration (Figures 8 & 11) Model 8013 cam positioners, when furnished with valves are factory mounted and calibrated following order specifications. However : If positioner is separately supplied. If action sense is changed. If positioner is reinstalled on an actuator having a different action on the valve. If some of electric elements were replaced etc... the calibration is necessary. It will be performed as follows : During these operations a potentiometer will allow, from a dc. regulated power supply, to obtain variations in signal. They will be controlled by a milliameter connected to the terminals. 1. Connect the electrical signal leads and proper supply pressure (see chapter INSTALLATION Electric circuit and Pneumatic circuit ). 2. Set input signal at the proper value corresponding to the valve closing. 3. Turn screw (6) of the force-balance spring (8) to have it approximately parallel to the joint of case. 4. Act alternatively on adjustment spring screw (52) and on turnbuckle (263) to obtain both valve closing and a space about 3/32 (2,5 mm) between the edge of the back lever (261) and the edge of the slot of positioner case (see Figure 8). 5. Set the signal at the proper value for the valve opening, then verify the actuator stem travel. If it does not corresponds to the rated stroke of the valve, proceed as follows : 6

7 A. If the positioner is mounted with the linear active cam lobe: Loosen nut (7) and turn adjusting screw (6) in a way on another, according to the correction to be made, (see Figure 4). The following table gives the rotating sense corresponding to each case. Actuator action Open on air failure Close on air failure Correction to be made on stroke Increase Decrease Increase Decrease Rotation sense of adjusting screw (6) Towards the right Towards the left Towards the left Towards the right 6. Repeat in succession operations 2 to 5 until the begining and the end of valve stroke agree with the minimum and the maximum of signal. 2,5 mm (3/32 ) Only on positioner mounted on Air-to-Extend Actuator Stem (#37), equipping a valve with plug located UNDER seat ring(s). If the positioner is mounted with the equal percentage active cam lobe: Rotate turnbuckle (263) so as to modify forcebalance spring (8) reaction until actuator stem is in the right position. If the positioner back lever (261) comes to stop on the case, correct its position by turning the force-balance spring adjusting screw (6). 2,5 mm (3/32 ) Figure 8 Position of the ack lever for Calibration maintenance Warning De-energize electric and pneumatic circuits before service or maintenance. Only qualified personnel to service this equipment. Metering Tube (Figures 9 & 10) The metering tube (59) for the nozzle air supply is furnished with a clean-out plunger which forces a small wire through the jewel orifice. The metering assembly can be removed and checked prior to relay disassembly. Relay (Figure 9) Disassembly: 1. Disconnect air tubing. 2. Unscrew the four relay mounting screws and remove relay from the case. 3. Remove metering tube, holding plug and drop the plug and spring from the relay body. 4. Remove the six screws which hold the relay cap, diaphragm S/A and bellofram plate, gasket and spring to the relay body. 5. Clean parts with a clean soft cloth. Use solvent if oil or grease is present (do not use solvent on diaphragms). low out parts with clean dry air. Replace all damaged parts. Reassembly: 1. Replace spring and position gasket on the relay body. Place ellofram plate S/A, diaphragm S/A and cap. Align holes in this elements with those of the relay body. Correct alignment is simplified by use of external reference mark. 2. Insert two screws 180 apart through this assembly. Replace and tighten the six screws. 3. Assemble relay plug, spring and holding plug. Establish correct position of relay and fasten on the positioner case. If relay repairs are required it is recommended that a new temporary relay be adapted, permitting to minimize time out of service. Nozzle (Figure 10) To clean nozzle (16) shut off air supply; loosen screw and remove flapper (46) from beam (41). Unscrew nozzle (16) from case. Clean out hole with solvent and clean dry air. Screw nozzle into the case, replace flapper on the beam and tighten screw. Flexure Strip Replacement (Figures10&11) 1. Shut off electric signal and pneumatic supply. Remove positioner cover and disconnect coil leads from the terminal board. Disengage the end of the force balance spring from the adjusting screw. 2. Remove the two mounting screws and lift the entire operating mechanism from the case. 7

8 GASKET METERING TUE S/A MOUNTING SCREW RELAY PLUG SPRING HOLDING SCREW GASKET CAP DIAPHRAGM S/A ELLOFRAM PLATE S/A SPRING RELAY ODY HOLDING SCREW Figure 9 Relay A SUPPLY PRESSURE OUTPUT TO ACTUATOR,,,,,,, 5C ,, SUPPLY OUTPUT NOZZLE PRESSURE PRESSURE ACK PRESSURE Figure 10 Cross Section of the Type 8013 Electropneumatic Positioner with Cam PARTS REFERENCE Ref. Part Name Ref. Part Name Ref. Part Name 3 Cover 4 Mounting Screw 5A Uper pole piece 5 Lower pole piece 5C Magnet 6 Adjusting screw (Force balance spr.) 8 Spring (Force balance) 11 Nut (Force balance spring) 14 Case 15 Terminal board S/A 16 Nozzle 20 Relay S/A 22 Mounting bracket 29 Screw (Mounting bracket fastening) 32 External lever 36 Circlips 39 Spring bracket 40 Coil S/A 41 eam 42 Screw (Flexure Strip Fastening) 43 Stop Locknut 44 Machine screw (coil stop) 45 Machine screw (coil & flap. fasten.) 46 Flapper 49 Flexure strip 50 Flexure strip 52 iasing spring S/A 52 iasing Spring (Incl. in ref. 52) 59 Metering tube S/A 71 earing post (bearing lever adapter) 74 Flame arrestor 80 earing post (Cam/back lever S/A) 82 earing lever 86 earing (Cam/back lever S/A) 87 Cam 89 Washer 90 Nut (Cam/back lever S/A) 91 Retaining clip 261 ack lever Recommended spare parts Instruction F 8

9 Coil Screw (45) Coil S/A (40) Force alance Spring Adjusting Screw (6) Machine Screw (44) Locknut (7) (Adjusting Screw) Coil Lead iasing Spring (52) iasing Spring Screw Mounting Screw (4) Coil Screw (45) Machine Screw (44) Alignement Rod (1/8 Dia.) Adjustment Spring Screw iasing Spring racket (39) iasing Spring (52) iasing Spring Screw Mounting Screw (4) Flexure Strip (49 & 50) Flapper (46) Upper Pole Piece (5A) Screw (42) Alignment Wedge (5/32 High) Flexure strip (49 & 50) Force alance Spring Adjusting Screw (6) Figure 12 eam Alignment 3. Remove screws and flexure strips from the beam. Replace coil if necessary per instructions below. 4. Replace damaged flexure strips and reattach beam to the magnet with flexure strips and screws. Do not tighten screws. Align the beam per instructions below. Coil replacement Force alance Spring (8) Figure 11 Coil and Flexure Strip Replacement 1. Remove the entire operating mechanism as described in Streps 1 through 3 above. Unscrew screws (44 & 45) freeing force coil (40) from the beam. 2. Attach replacement force coil loosely to the beam with screws (44 & 45). Note: Coil stop screw (44) should not extend into the coil bobbin. 3. Reattach beam to magnet with flexure strips and screws and align the beam. eam Alignment (Figures 10 & 12) 1. Insert a 1/8 (3,175 mm) diameter cylindrical rod into alignment holes in the coil, beam and magnet and place on the magnet, between the beam and the coil, a wedge 5/32 (3,97 mm) high and 1/32 (1 mm) max. in thickness. Rod and wedge materials should be non-magnetic. 2. Tighten two screws (42) of inner flexure strip to beam; two screws of outer flexure strip to magnet. 3. Replace operating mechanism in case. Position the biasing spring bracket (39) in place and tighten in position with two mounting screws (4). 4. Exert light downward pressure on beam between the 5/32 high wedge and the nozzle. Tighten the remaining flexure strip screws (42). 5. Tighten the force coil screw (45) and remove alignment rod and wedge. 6. Adjust coil stop screw (44) in order that flapper travel in front of the nozzle should be approximately 0.8 mm (1/32 ). Tighten stop locknut (43). Reattach force balance spring (8) on adjusting screw (6) and connect biasing spring (52) on the beam by means of its screw. 7. Connect coil wires to terminal board according to the desired positioner action. Proceed with calibration and replace cover. Terminal oard Replacement If it becomes necessary to change the input signal range of a positioner, a terminal board and coil adapted to accomodate the new signal should be ordered from the Spare Parts Department. To change terminal board proceed as follows: 1. Remove entire operating mechanism from case as described in Steps 1 and 2 of paragraph Flexure Strip Replacement. Disconnect signal input leads from terminal board. 2. Unscrew two screws holding terminal board to case. 3. Insert the new terminal board and fasten securely to case. 4. Insert entire operating mechanism in case and tighten the two screws (4) after placing biasing spring bracket (39). Reconnect signal input leads. 5. Reattach force balance spring (8) on adjusting screw (6). 6. Connect coil leads to terminal board according to the desired positioner action. Proceed with calibration and replace cover. 9 Instruction F

10 trouble shooting The following conditions are necessary for trouble-free operation: 1. Proper mounting of cam (87) and back lever (261) S/A. (See chapter INSTALLATION). 2. Proper fastening of positioner bracket on actuator yoke. (See chapter INSTALLATION). 3. Correct positioning of the force balance spring (8). (See chapter INSTALLATION). 4. Proper positioning of coil lead connections and signal leads to terminal board. (See chapter INSTALLATION). 5. Correct pneumatic connections. 6. Supply pressure required by valve operating conditions and sizes. (See chapter INSTALLATION and refer to valve catalog or serial plate). 7. Proper control signal and input impedance for utilized controller. (See chapter INSTALLATION and refer to table of Figure 4 of Instruction sheet No ES E). 8. Coil stop adjusted to allow approximately 0,8mm ( 1 /32 ) flapper travel in front of nozzle. 9. All mechanism components fastened firmly as required. 10. Proper nozzle size selected. Number of nozzle is stamped on its body. The table below indicates nozzle number used for each actuator No. Actuator size 20 psi supply Nozzle Number 35 psi supply Pneumatic circuit: In the event of faulty operation of the positioner, where the cause is not readily apparent, check air system as follows: 1. Exert sufficient force on the flapper to cover the nozzle. Valve stem should travel its full stroke. 2. If response is other than indicated in the above steps, push cleanout plunger of metering orifice. Inspect for plugged nozzle. Check to see if metering orifice body is properly seated in the relay. If difficulty still persists, disassemble and clean relay. Electrical circuit: After checking pneumatic circuit, the electrical circuit should be checked with an ohmmeter as follows: 1. Disconnect signal leads from terminal board S/A. 2. Connect ohmmeter leads to positioner terminal board leads and check positioner circuit resistance with nominal resistance indicated on identification plate. Table of Figure 4 of the Instruction No ES E shows the nominal resistance of main circuits. 3. Disconnect coil lead from positive terminal and connect to one of the ohmmeter leads. Connect other ohmmeter lead to negative terminal. Force coil resistance value should approximate value indicated in table of Figure 4 of the Instruction No ES E. 4. If force coil resistance is approximately correct but positioner circuit resistance is not, repair or replace terminal board. If force coil resistance is not correct replace force coil. 5. Remove ohmmeter lead from negative terminal and connect it to coil stop screw. Check for short in force coil. Replace the coil if ohmmeter indicates a value other than very high resistance (pratically infinite). 107, av. Ch. de Gaulle Neuilly sur Seine Cedex - Tel.(1) Telecopier (1) Telex F FRANCE PLANTS, SPARE PARTS and AFTER SALES DEPARTMENTS: 3, rue Saint Pierre Condé sur Noireau Tel Telecopier Telex F Doc.Technique MN Condé DESKTOP PULISHING. apple February 1994