service manual
Contents
1. MODELS 75211 50 Gear Pump Drive w 4 20 mA 3600 RPM 115 V 75211 55 Gear Pump Drive w 4 20 mA 3600 RPM 230 V CE PROPRIETARY Information contained in this manual is proprietary to the BARNANT COMPANY division of COLE PARMER INSTRUMENT COMPANY INC No reproduction for other than the intended use of maintaining the product described herein is permitted without the permission of BARNANT Barnant Company Division of Cole Parmer Instrument Company Inc 625 East Bunker Court Vernon Hills Illinois 60061 1844 847 549 7600 847 247 2929 Fax 800 323 4340 A 1299 0985 Edition 02 TABLE OF CONTENTS PAGE INTRODUCTION oe ee eae 3 SAFETY CONSIDERATIONS 4 THEORY OPERATION eer pie 5 DETAILED CIRCUIT OPERATION OF CONTROLLER 5 6 lt eee 11 REPAIR PROCEDURES lt 12 REPLACEMENT PARTIES 14 15 SPECIFICATIONS oe I A 17 INTRODUCTION Service for this product is performed at three levels the customer2. 4 RMS 5 80mvV 86 3 Sep 1996 09 38 29 Waveform 1 Test point 6 Waveform 2 Output of scr bridge across motor Waveform 3 PUT charging ramp test point 5 Waveform 4 Motor current measured using TEK TPC 202 current probe EXTERNAL GENERAL OVER VIEW A In this mode the board integrates circuitry from the internal mode with additional circuitry to allow remote speed control through voltage or current as well as control through contact closures Power Supply A The 22 volt non isolated supply is derived by a rectified voltage at TP 8 dropped by resistor network R117 R132 R133 R134 R135 R136 these are multiple smt style resistors and regulated to approximately 22 VDC at TP 6 by VR4 The voltage will charge C5 through CR8 to filter the ripple and produce a regulated supply B The 15 volt non isolated supply is derived by tapping off C5 through R33 and regulated by VR2 Capacitor C16 filters any ripple separate 15 volt supply used to drive the circuitry on the isolated side of the circuits is derived for transformer T1 rectified by D1 D4 filtered and bypassed by C23 C24 then fed into regulator U8 The 15 volts is set by R106 R107 and filtered by C20 This voltage is available at J16 pin 1 Control Section In this controller all user adjustable controls e g speed pot and remote features are isolated from the ac line The final output from the opto coupl
3. component of this unit be absolutely certain that all power to circuitry is removed If any functional checks to be performed while power is applied chassis is disassembled care must be exercised CAUTION A This is a line operated device and is not isolated from ground Powering the device under test using an isolation transformer is strongly recommended B Do not inadvertently short any part of the printed circuit card to ground as severe damage will result The variable speed controller employs a phase controlled rectifier bridge to vary the power applied to a permanent magnet DC motor The bridge will conduct current only when the power line voltage exceeds the voltage across the motor terminals Varying the point at which the bridge starts to conduct relative to the phase of the line voltage can therefore control the power to the motor An inner torque outer speed regulator loop controls the phase angle at which the bridge starts conducting The speed of the motor is directly proportional to the back EMF generated by the motor Comparing the voltage across the motor terminals against the speed reference signal at the center tap of the front panel speed control pot an op amp generates a torque reference signal The torque supplied by the motor is directly proportional to the current supplied to the motor The op amp amplifies the voltage drop across a sense resistor providing
4. that allows contact closure start stop control of the drive motor Additional circuitry allows the user to remotely select the front panel or linear input speed references using a contact closure The output of the commanded 4 20 mA and 2 10 VDC inputs are optically isolated from the ac line minimum 1250 Vac for 115Vac units 1900 Vdc for 230Vac units DETAILED CIRCUIT OPERATION INTERNAL MODE GENERAL OVER VIEW A The 75211 series controller board employs modular SMT technology see figure 1 to provide a single board solution employing an SCR based power amplifier to drive permanent magnet motors Power Supply A AC line is brought in at J 3 and J 4 and routed through ON OFF switch contacts to power bridge consisting of CR1 CR2 CR7 CR11 B The rectified voltage at TP 8 is dropped by series resistor R26 or R35 and regulated to approximately 22 7 VDC at TP 6 by VR4 connected to J5 indicates power ON to circuitry Varistor RV1 and RC network R1 amp C1 suppress line noise generated externally and internally by motor and power bridge Output Drive A Motor power bridge consists of CR7 CR11 Q1 Q2 Diode CR13 bypasses the inductive current surges of the motor when the Power Bridge shuts off B Resistor capacitor combination consisting of R5 and C2 forms a snubber network for commutation noise suppression Control Section A Motor speed is set by front panel pot connected to J
5. 20 mA Full Speed Accuracy 3 F S Linear Resolution Overload Capability 10 V or 40 mA max 2 10 V Input 10 K ohms typical input impedance referenced to signal ground 2 V Stop 10 V Full Speed Accuracy 3 F S Linear Resolution Overload Capability 15 V max Only one of the analog inputs may be used at any one time The front end of the circuitis a differential op amp to allow for multiple units max 3 to be cascaded in series Current Input or parallel Voltage Input for control Both 4 20 mA and 2 10 VDC inputs are optically isolated from the ac line minimum 1250 Vac for 115Vac units 1900 Vdc for 230Vac units
6. 6 B A VREF is obtained by regulating the 22VDC supply with R34 and VR2 to approximately 12VDC This is routed through network R33 and R30 to DC ground Adjustment pot R33 sets maximum motor speed approx 10VDC at TP 1 Components R13 CRY and control acceleration deceleration of motor RPM D Set speed is controlled and regulated by differential amp U1 and related components R15 C7 R17 and R2 R37 All scaling is done at 5volts full scale for all op amp circuits As motor load increases back EMF picked off drive output resistor network R2 R37 and R3 TP 3 increases to 5 volts This is fed through R17 to pin 2 of U1 A causing TP 2 to charge integrator capacitor C10 via R18 to advance the SCR firing angle until the op amp equalizes its input voltages E Current limit of circuit is accomplished by monitoring the voltage drop of current sense resistor R4 feeding it through R19 and R11 to level amp U1 B and related components As current through R4 approaches 2 0 amps for 120 volt units 1 0 amps for 240 volt units voltage to TP 4 rises to approximately 5 0VDC This is fed through resistor network R22 and R23 at a 2 to 1 ratio into the peak detector CR10 amp C9 The output of the peak detector is buffered R21 amp Q4 by an emitter follower Q4 amp R25 amplifier which discharges integrator C10 retarding the SCR firing angle The resultant firing angle will be p
7. a signal proportional to the average current supplied to the motor The peak value of the signal is subtracted from the torque reference signal by a transistor The resulting torque error signal charges a capacitor firing the power bridge SCR s for a given line cycle Transient voltage suppression for the line is provided by line to line 5 Motor brush commutation noise is suppressed using a RC network 600 volt SCR s and 1000 volt diodes make up the power bridge and primary power supply Supply regulation is through a zener diode network SCR switching at zero cross is actually centered on a 10 volt window creating a secondary supply allowing a complete shut off of each SCR This voltage is also used to synchronize the SCR firing circuit to the line A simple RC network provides for a soft start circuit which provides a gentle acceleration of the motor The drives have linear speed control inputs These two inputs take either 2 10 volt dc or 4 20 and operate the drive over its full rated speed range The linear inputs generate a 1 5 volt span that is OP amp buffered for common mode up to 15 vdc This voltage is than fed through an offset OP amp to subtract 1 volt from the signal leaving 0 4 volt control signal for speed reference MOS switches select either the front panel control reference voltage or the linear input speed reference to control drive speed This stage also incorporates an additional MOS switch
8. cuits have to start at zero and then span This is accomplished by setting U4 A for an offset of 1 volt The result is a 0 4 volt control signal 013 is configured as an adjustable zener diode This will conduct at 6 volts to clamp off U3 A outputs of greater than 5 volts preventing excessive drive speed TROUBLESHOOTING Repairs on this unit are basically confined to either the unit s control PCB and or the drive motor assembly Where possible swap Known good parts to localize and isolate the problem following is a list of possible problems and remedies UNIT DOES NOT TURN ON NO POWER LIGHT 1 Fuse blown replace fuse 2 Power cord not connected properly check amp replace 3 ON OFF switch failure replace main controller PCB 4 Unit connected to dead outlet verify supply is HOT UNIT BLOWS FUSES 1 Motor drive failure check using known good motor 2 Defective controller PCB replace return to factory 3 Wrong fuse installed check fuse rating MOTOR WILL NOT RUN assumed functional motor 1 Defective ON OFF switch replace switch assy 2 Defective controller PCB ASSY Replace main controller PCB ASSY LOSS OF SPEED CONTROL OR IMPROPER SPEEDS 1 Defective controller PCB ASSY Replace main controller PCB ASSY 2 Unit out of calibration recalibrate controller MOTOR IMMEDIATELY RUNS WHEN POWER IS APPLIED 1 Power output triacs shorted replace main controller PCB ASSY For addit
9. distributor COLE PARMER and factory depot repair This manual describes distributor COLE PARMER service procedures Customer service procedures are described the operator s manual Customers are encouraged to perform service as described in the operators manual as well as in special circumstances where special skills and safety are not considerations To use this manual begin with the troubleshooting section to isolate the fault to a replaceable part The functional description and checkout procedure sections are also helpful in determining the faulty part Distributor COLE PARMER repair is limited to replacement of modules as detailed in the replacement parts list section The repair procedure section details disassembly and assembly procedures After repair the product should be calibrated and checked for proper performance Please refer to the operators manual A 1299 0935 for A APPLICATIONS DATA B PRODUCT DESCRIPTION C INSTALLATION D SETUP E OPERATION F USER CALIBRATION G USER TROUBLESHOOTING amp MAINTENANCE H ACCESSORIES SPECIFICATIONS SAFETY CONSIDERATIONS Servicing must be performed only by personnel trained and skilled in the methods of troubleshooting and repair of electro mechanical products Use of procedures other than those described in this manual may result in a safety hazard to service personnel and or customers A WARNING High voltage is present inside the unit when servicing any
10. er isolator drives the input of the aforementioned controller A Motor speed is set by front panel pot connected to J8 B Front panel speed reference voltage is generated by divider network R65 R56 and R53 to DC ground Adjustment pot R 65 sets maximum motor speed approx 4 0VDC at J16 pin3 C The 4 volt signal that is set above is routed through analog switch network SW1 A amp SW 1C which is the selection network for front panel speed or remote speed select and the foot switch control Switch SW1 A works opposite of SW1 B when local remote switch is in the LOCAL position a low is placed at pind SW1 B turning it off The low is prevents conduction of D8 allowing pull up R75 to enable SW1 A selecting the front panel speed reference When local remote switch is in the REMOTE position a high is placed at pind SW1 B turning it on selecting the remote speed inputs The high causes conduction of D8 transistor 011 conducts pulling 13 SW1 B low deselecting the front panel speed reference In this mode the user can select either front panel or remote speed references by grounding J6 pin4 interface connector D The foot switch control works similar manner as above When local remote switch is the REMOTE position a low is placed at SW1 B turning it off The low is generated by Q10 conduction through D7 pull up R70 this prevents the speed reference voltage regardless of front panel
11. ional information regarding the unit please refer to the following A 1299 0935 operators manual REPAIR PROCEDURES A WARNING High voltage is present inside the unit when servicing any component of this unit be absolutely certain that all power to circuitry is removed If any functional checks are to be performed while power is applied and chassis is disassembled care must be exercised TO DISASSEMBLE UNIT PROCEED AS FOLLOWS A Remove the three pan head screws on each side of the unit s cover B Carefully unplug all connectors from PCB and separate enclosure assembly from chassis assembly TO REPLACE PCB ASSEMBLY A Remove jackscrews from the DB 9 connector on the back of chassis B Loosen circuit board guide and slide PC board forward and up C Disconnect wire leads D Position new PCB in circuit board guide and slide down and back E Replace the jackscrews on DB 9 connector and tighten the circuit board guide F Reconnect wire leads from chassis see TABLE 1 TABLE 1 75211 50 75211 55 GROUND WIRE from ground stud GROUND WIRE from ground to J 15 stud to J 15 BLUE WIRE from ac line filter to BROWN WIRE from ac line J 4 filter to J 3 BROWN WIRE from ac line filter to BLACK WHITE WIRE from ac J 3 line filter to J 4 G Check calibration per applicable calibration specification 12 REPLACE MOTOR A Follow step A in DISASSEMBLE UNIT B Remove groundnut and wires from PCB noting wiri
12. ng C Loosen motor mounting bolts D Slide motor forward and remove from chassis E Install new motor Reattach ground and motor leads Slide motor back and tighten bolts TO REPLACE SPEED POTENTIOMETER A Remove knob and mounting hardware B Slide pot assembly out of the control panel C Install new pot assembly in reverse sequence D Verify that when the pot is turned fully counter clockwise and the indicator knob is set fully counter clockwise 0 the indictor TO REPLACE ON OFF SWITCH A Remove switch sealing boot using care to prevent damage to it B Slide switch assembly out of control panel noting which side keyway slot on bushing is facing C Insert switch assembly into control panel with keyway slot in proper direction reinstall boot and tighten until switch will not rotate TO REASSEMBLE UNIT PROCEED AS FOLLOWS A Carefully plug all connectors into PCB observing proper orientation of plugs see TABLE 1 B Reinstall the six pan head screws on the cover of the unit REPLACEMENT PARTS LISTING The following is a list of stockable motor assemblies main control PCB assemblies and their reference schematic diagrams for all indicated models MODELS MODEL MAX RPM Motor PCB REFERENCE Assembly SCHEMATIC 75211 50 3600RPM 5992 0001 CR E 2274 0003 CR E 2268 115V 75211 55 3600RPM 5992 0002 CR E 2274 0004 CR E 2268 230V The follo
13. ontrol for maximum 4 Measure amp turn pot R 90 on PC Board to obtain proper motor terminal voltage as follows 100 0 5 vdc for 115 vac units 200 0 vdc 1 0 vdc for 230 vac units 5 All other pots are factory adjusted and should not be field adjusted 6 Seal pot adjustments and reassemble unit SPECIFICATIONS LINE VOLTAGES MODEL NOM MIN MAXIMUM 75211 50 115 volts 90 volts 130 volts 75211 55 230 volts 190 volts 260 volts LINE FREQUENCY all models SINGLE PHASE 50 60 hertz TEMPERATURE amp HUMIDITY MINIMUM MAXIMUM OPERATING TEMPERATURE 0 40 STORAGE TEMPERATURE 25 C 65 C HUMIDITY NON COND 10 90 Remote Start Stop amp Remote Local The remote control inputs work with current sinking outputs open collector NPN transistor outputs with or without passive pull up resistors or contact closures to DC common earth ground A continuous active low to the Remote Start Stop input causes the drive to run while a continuous active low to the Remote Local input switches speed control to the front panel speed control Input_Voltage Input Current High State 15 VDC Typ 100 uA Max leakage Low State 0 8 VDC Max 1 5 All inputs will be electrically isolated from the ac line minimum 1250 Vac for 115Vac units 1900 for 230Vac units Remote Analog Input Ref ISA S50 1 4 20 mA Input 250 ohms typical input impedance referenced to signal ground 4 mA Stop
14. or remote selection from driving the opto coupler isolation drive By grounding J6 interface connector the low prevents conduction of D7 transistor Q10 turns off allowing pull up R73 to enable SW1 C allowing the speed reference voltage selected to drive the opto coupler isolation drive E The opto coupler isolation drive consists of OPT1 and U4 B this circuit works by taking a voltage at 5 U4 B and having the output of the op amp drive the input led of OPT1 until the op amp equalizes its input voltages at pin6 Because there is two detectors within opt1 one is within the feedback path another in a separate op amplifier U5 B A linear drive voltage will give a linear output of the same voltage pin7 U5 B This control voltage typically 0 10 volts will drive the SCR amplifier input This circuit also serves to provide isolation barrier of approx 3500 volts between the grounded and hot referenced control circuits F The linear inputs consist of U3 A dual op amp This is split one for voltage one for current The voltage input enters pin1 J6 and ground pin3 J6 through R78 The voltage across R78 is divided by 2 and buffered by U3 A to generate a 1 5 volt output The current input enters pin2 J6 and ground pin3 J6 through R47 The voltage across R47 is buffered by U3 B to generate a 1 5 volt output G Because the scaling of the electronics the outputs of the above cir
15. roportional to the difference between the torque reference charging current R18 and the torque feedback discharging current R25 F The SCR will fire when the integrator C10 voltage is equal to the PUT Q9 reference voltage VR3 R11 amp R12 Line synchronization is achieved by allowing the reference voltage to drop to zero 10 volt window with each line cross thereby discharging C10 through 09 C10 amp 09 form a relaxation oscillator whose period is proportional to the rate of charge of C10 When the voltage across C10 is equal to the reference voltage the PUT Q5 is forward biased and will conduct discharging C 10 through the base emitter junction of buffer Q6 R9 bypasses any leakage current while C11 filters out noise pulses G The pulse output of the relaxation oscillator C10 amp 09 is buffered and amplified by Q6 and level shifted by a Darlington pair Q3 amp Q8 on 115 volt units or Q8 amp Q7 on 220 volt units fire the Power Bridge SCR Q1 amp Q2 R7 amp R29 limits the gate current while CR6 amp CR12 blocks back conduction of the Darlington pair H For a detailed view of these signals see figure 2 waveform and related descriptions iy 6 oa siin 5 mi ai Figure 1 Typical controller board Tek 25 0 5 5 789 Acqs JA 120 Hz 1 66 Chi RMS 116 6 V 2 Mean 32 1 Ch4 Mean 1 84m
16. wing is a list of commonly used parts applicable to the above model LISTINGS DESCRIPTION BARNANT Part Speed adjustment knob A 2583 ON OFF switch assembly 115 volt Non CE models 1264 ON OFF switch assembly 230 volt CE models 7265 Switch sealing boot all models A 2984 Speed Pot Assembly ten turn 5633 0001 T3 15 5 x 20 MM fuse 115V systems B 1115 0057 T1 16 5 x 20 MM fuse 230 V systems B 1115 0042 Rubber foot on chassis A 1390 0002 CALIBRATION After repairs are made the unit must be tested to assure proper performance to specifications In many cases servicing personnel to accomplish this can use factory QC checkout procedures For calibration procedures please refer to the following CAL SPECIFICATION listings table appropriate to the model that is being serviced MODEL CAL SPECIFICATION 75211 50 CAL 1877 75211 55 CAL 1877 Additional technical specifications are available in the unit s OPERATOR MANUAL The following procedure may be used to roughly tweak an out of spec unit A BEFORE PROCEEDING FURTHER PLEASE NOTE ALL WARNINGS AS LISTED IN THE SAFETY CONSIDERATIONS SECTION A 1 Phillips screwdriver B Non metallic pot tweaker C Hand held tachometer 1 Follow procedure for unit dissasembly 2 Plug unit into the appropriate line voltage If this can be done through an adjustable variac to e g 115 vac 115 volt units or 230 vac 230 volt units 3 Turn unit on set speed c
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