RESISTIVITY
MONITOR/CONTROLLERS
Installation • Operation • Maintenance
User Manual for Models: 750, 752, 753, 762
2450 Impala Drive
Carlsbad, CA 92010-7226 USA
Tel: 1-760-438-2021
Fax: 1-800-869-7668 / 1-760-931-9189
www.myronl.com
Water Quality Instrumentation
Accuracy • Reliability • Simplicity
TABLE OF CONTENTS
SECTION PAGE
1 INTRODUCTION
1.1 SCOPE ........................................................................................................................................1
1.1.1 FUNCTIONAL DESCRIPTIONS .....................................................................................1
1.1.2 MONITOR APPLICATIONS ............................................................................................ 1
1.2 MONITOR SPECIFICATIONS .....................................................................................................1
1.3 RESISTIVITY CELLS ...................................................................................................................2
1.3.1 CELL PRODUCT SPECIFICATIONS ..............................................................................2
1.4 OPTIONAL INTERFACE FEATURES ..........................................................................................2
1.5 HOW TO ORDER ........................................................................................................................ 2
2 INSTALLATION
2.1 GENERAL ....................................................................................................................................3
2.2 MECHANICAL INSTALLATION ...................................................................................................3
2.2.1 SURFACE INSTALLATION .............................................................................................4
2.2.2 PANEL MOUNTING ........................................................................................................4
2.2.3 CELL INSTALLATION .....................................................................................................4
2.3 ELECTRICAL INSTALLATION .....................................................................................................4
2.3.1 MAIN AC POWER INSTALLATION................................................................................. 4
2.3.2 CELL INSTALLATION .....................................................................................................5
2.3.3 ALARM RELAY INSTALLATION ..................................................................................... 5
2.4 OPTIONAL INTERFACE CONNECTIONS ..................................................................................5
2.4.1 220 VAC CONVERSION.................................................................................................5
2.4.2 0-5/0-10 VDC RECORDER BOARD............................................................................... 6
2.4.3 4-20 mA AND 4-20D TRANSMITTER BOARDS .............................................................6
3 OPERATING PROCEDURES
3.1 GENERAL ....................................................................................................................................7
3.2 SWITCH AND INDICATORS CONTROLS .................................................................................. 7
3.2.1 MODEL 750 ....................................................................................................................7
3.2.2 MODEL 752 AND 753 .....................................................................................................7
3.2.3 MODEL 762 ....................................................................................................................7
3.3 OPERATIONAL CHECKOUT PROCEDURES ............................................................................8
3.3.1 MODEL 750 ....................................................................................................................8
3.3.2 MODEL 752, 753 AND 762 .............................................................................................8
4 COMPONENT IDENTIFICATION, CALIBRATION AND PREVENTIVE MAINTENANCE
4.1 GENERAL ....................................................................................................................................9
4.2 PRIMARY COMPONENT IDENTIFICATION ...............................................................................9
4.3 CALIBRATION PROCEDURES .................................................................................................10
4.3.1 METER MECHANICAL ZERO READING.....................................................................10
4.3.2 FULL SCALE CALIBRATION PROCEDURES .............................................................10
4.3.2.1 MODEL 750 .................................................................................................. 10
4.3.2.2 MODELS 752, 753 AND 762 ........................................................................ 10
4.3.3 INTERNAL SET POINT ADJUSTMENT .................................................................... 11
4.3.4 0-5/0-10 VDC RECORDER BOARD ......................................................................... 11
4.3.5 MODEL 753 WITH 4-20mA or 4-20D OPTION ..........................................................11
4.4 PREVENTIVE CARE ................................................................................................................. 12
5 APPENDIX
A REPLACEABLE COMPONENTS CHART .................................................................................13
SECTION 1
Introduction
1.1 SCOPE
This manual provides the necessary information to install,
operate and maintain the Myron L Company’s 750/760 Series
Resistivity Monitors. Sections 1 thru 3 provide the user with a
Monitor’s applicational description, mounting, wiring and
operational procedures. Section 4 identifies their primary
components and provides the user with easy-to-use calibration,
and preventive maintenance procedures.
Section 5 (Appendix) provides Replaceable Components
Charts.
1.1.1 FUNCTIONAL DESCRIPTIONS
All models have drip/weather-proof housing which can be panel
or surface mounted. The 750 models are a compact 6.0" x 5.0"
(152mm x 122mm). The 762 is 6.0" x 10.8" (1 52mm x 275mm).
All model front panels are equipped with bright green and red
LEDs that indicate “Above” or “Below” set point readings. Also
standard on all models is a heavy-duty 10 amp Alarm relay,
activating on decreasing readings.
For specific Monitor configurations, reference the following
individual model descriptions:
Model 750
Provides a front panel accessible set point adjustment knob in
place of an analog or digital meter readout display.
Model 752
Set point is internal to discourage unauthorized adjustments.
Standard front panel is equipped with a linear analog meter
display and a “SET POINT CHECK” switch.
1.2 MONITOR SPECIFICATIONS
RANGES:
0-20 megohm-cm
0-2 megohm-cm
0-200 kilohm-cm
0-500 kilohm-cm (Model 750 only)
0-20, 0-2, 0-0.20 megohm-cm, (Model 762 only)
READOUT:
Model 752: 2
Model 753: 1/2" x 3 1/2 Digit (13mm) Digital
Model 762: 4
ACCURACY:
Model 753: ±1 % of span
Other Models: ±2% of span
SENSITIVITY:
0.5% of span
STABILITY:
0.05% of span
REPEATABILITY:
0.1% of span
CELL INPUTS:
1 Input (standard)
3 Cell input (optional 762 only)
1
/2" (63mm) Analog
1
/2" (114mm) Analog
Model 753
Set point is internal to discourage unauthorized adjustments.
Standard front panel is equipped with a digital LCD meter
display and a “SET POINT CHECK” switch.
Model 762
Set point is internal to discourage unauthorized adjustments.
Standard front panel is equipped with a three (3) Range select
switch (0-20, 0-2, 0-0.2 megohm), a linear analog meter display
and a “SET POINT CHECK” switch.
1.1.2 MONITOR APPLICATIONS
1 Deionized (Dl) and distillation ultra-pure treatment
systems
2 Electronics
3 Food Processing
4 Plating
5 Power Plants
6 Laboratories
Introduction
RELAY FUNCTION:
Single set point control:
Continuously adjustable 0-100% of span
Indicators:
“ABOVE” (green) and “BELOW” (red) set point LEDs
Contact Rating:
SPDT 10 amp @ 250 VAC, 30 VDC. Relay activates on
decreasing readings
POWER SPECIFICATIONS:
115 VAC, 50/60 Hz ± 15%, 25mA
220 VAC, 50/60 Hz ± 15% (Optional)
AMBIENT TEMPERATURE RANGE:
-22°F ( -30°C) to 140°F (60°C)
CONSTRUCTION:
Fully gasketed heavy-duty ABS for corrosion resistance,
NEMA type 3 rated
WEIGHT:
(750 Series) 2 Ibs (0.9 kg)
(762) 3 Ibs (1.4 kg)
1
1.3 RESISTIVITY CELLS
All 750/760 Series Monitors use a CS10 Cell. These reliable
sensors feature two integral thermistors to ensure accurate and
rapid automatic temperature compensation. The sturdy
polypropylene bushing is modular for easy, inexpensive
replacement. Several alternatives for the metal portion of the cell
are available, depending on the demands of the application.
1.3.1 CELL PRODUCT SPECIFICATIONS
CONSTANT:
0.05
TEMPERATURE COMPENSATION:
Two integral thermistors provide automatic TC to 25°C
between 32-212°F (0-100°C)
PRESSURE/TEMPERATURE LIMITS:
100 psi (689.6 kPa) ~ 212°F (100°C)
BUSHING:
Modular Polypropylene threaded .75" NPT
CABLE:
Shielded Belden 8724; 10' (3 meters) standard,
Prespecified lengths of 25' (7.5 meters) or 100' (30 meters)
also available.
DIMENSIONS:
Metal portion 1.2" (95 mm) L; 0.5" (13 mm) DIA
1.4 OPTIONAL INTERFACE FEATURES
1 0-5/0-10 VDC Recorder Interface
2 4-20 mA Loop Powered Isolated Output (753 only)
1.5 HOW TO ORDER
EXAMPLE:
MODEL TYPES:
750: Small Controller with front panel “Set Point” adjustment
knob.
1
752: Small Monitor with 2
/2" analog meter display.
753: Small Monitor with 1/2" LCD digital meter display.
762: Large Monitor with 4 1/2" analog meter display and three
(3) range select switch.
RANGE SCALES:
1: 0-20 megohm-cm
2: 0-2 megohm-cm
3: 0-200 kilohm-cm
4: 0-20, 0-2, 0-0.20 megohm-cm (Model 762 only)
5: 0-500 kilohm-cm (Model 750 only)
3 4-20mA Self Powered Isolated Output (753 Only)
4 Three (3) Cell Input (762 only)
2
OPTIONS:
03: 3 Cell Input (Available on the 762 Monitor only)
510: 0-5/0-10 VDC Recorder Interface (Available on
all Models)
420: 4-20 mA Loop Powered Isolated Output
(Available on the 753 Monitor only)
420D: 4-20 mA Self Powered Isolated Output
(Available on the 753 Monitor only)
HOW TO ORDER CS10 CELL(S):
CS10-S 316 Stainless Steel
-T Titanium
Introduction
SECTION 2
Installation
2.1 GENERAL
This section contains the recommended procedures required to
properly install the 750/760 Series Monitors, to connect the
Cell(s), Alarm relay, Recorder and/or Transmitter cable
connections.
WARNING!
The Myron L Company recommends that all mounting and
electrical installation procedures be performed by trained and
authorized personnel ONLY! Failure to do so could result in
damage to equipment and/or property.
2.2 MECHANICAL INSTALLATION
All Monitor electronics are packaged inside drip/weatherproof
housings. Their physical dimensions have been designed to
allow for both surface and panel mounting.
There are three basic guidelines to consider when selecting the
monitor’s mounting location.
1 Select a site that limits the Monitor’s exposure to
excessive moisture and corrosive fumes.
2 For best results, position your control area as close as
possible to the point(s) being monitored.
Installation
3
NOTE:
750/760 Series Monitors are not designed to operate with Cell
cable lengths that exceed 100'(30 meters).
3 If at all possible, mount the monitor at eye level for
viewing convenience.
2.2.1 SURFACE INSTALLATION
Surface mounting will require two (2) 1/4"-20 mounting screws
(supplied). See Fig. 2-1 for hole drilling locations. For ease of
surface mounting, a surface mounting plate is available.
STEP 1 Select your site location, mark and drill the two (2)
required mounting holes.
STEP 2 Place the Monitor’s mounting threads in alignment with
the surface mounting holes.
STEP 3 Insert and securely fasten the two (2) 1/4"-20 mounting
screws.
STEP 4 Slide the enclosure through the panel cutout until its
flange contacts the panel.
STEP 5 Insert mounting screws through the flange mounting
holes and tightly secure.
STEP 6 Reconnect all panel cable(s)/wires to Control board.
(See Fig’s 4-1 and 4-2 for panel and Control board
cable connector designations.)
2.2.3 CELL INSTALLATION
Fig. 2-2 illustrates how to properly assemble and install the
CS10 Cell assembly into a “T” type mounting fixture. Improper
assembly could result in damage to equipment and/or property.
A CS10 Cell’s mounting orientation must provide a continuous
and adequate circulation flow to prevent the trapping of air
bubbles within the Cell’s electrode area. Failure to do so will
result in conditions that will prevent the Cell from functioning
properly.
STEP 1 Verify that the Cell’s Fitting assembly is properly
assembled.
STEP 2 Insert the Cell Fitting assembly into the “T” mounting
fixture as shown in Fig. 2-2 and tightly secure.
2.3 ELECTRICAL INSTALLATION
The electrical installation procedures provided in this manual are
common to all 750/760 Series Monitors. See Fig. 2-1 for the
hole dimensions of the enclosure’s various cable access holes.
NOTE:
All water tight cable restraints are user supplied.
2.2.2 PANEL MOUNTING
A panel mounting fastening kit is provided with all 750/760
Series Monitors. Panel mounting will require the use of the
fastening kits two (2) 4-40 mounting screws/nuts or two (2) # 4 X
1
/2" sheet metal screws. See Fig. 2-1 for panel cutout
dimensions.
STEP 1 Select your site location, mark the appropriate panel
cutout and complete the necessary panel cut.
STEP 2 Carefully unfasten and separate the Monitor’s front
panel from its enclosure.
STEP 3 Disconnect all panel cable(s)/wires from the Monitor’s
Control board.
2.3.1 MAIN AC POWER INSTALLATION
The following procedures are to be used to install a standard
115 VAC main power source. For the procedures to install the
optional 230 VAC main power source, the user must first
complete the 115V to 230V conversion procedures in Section
2.4.1.
STEP 1 Verify that the facility’s main AC power source is turned
“OFF” or disconnected.
STEP 2 By following the STEPS 2 and 3 in Section 2.2.2,
remove the Monitor’s front panel.
STEP 3 Place the facility’s AC power cord and water tight cable
restraint into the enclosure’s appropriate access hole.
STEP 4 Neatly connect cable wires to the Control board TB1
terminal block connectors as shown in Fig. 2-3.
4
Installation
2.3.2 CELL INSTALLATION
STEP 1 Place the Cell’s interface cable and water tight cable
restraint into the enclosure’s appropriate access hole.
STEP 2 Neatly connect the cable wires to the Control board’s
TB3 terminal block connectors as shown in Fig. 2-3.
2.3.3 ALARM RELAY INSTALLATION
STEP 1 Place the user supplied Alarm relay interface cable and
water tight cable restraint into the enclosure’s
appropriate access hole.
STEP 2 Neatly connect cable wires to the Control board’s TB2
terminal connectors as shown in Fig. 2-3 and explained
below:
All Myron L Company Resistivity Monitor/Controllers are
equipped with a relay which is designed to energize/deenergize
when the set point is crossed. (See P.11, Sec. 4.3.3. for set point
adjustment procedure) The relay energizes on decreasing
readings.
Since various devices (alarms, solenoid valves, etc.) controlled
by your Myron L instrument can operate on different voltages,
the power the relay is to control must be connected by you. Any
common AC or DC voltage may be used, provided the current
load does not exceed 10 amps.
2.4 OPTIONAL INTERFACE CONNECTIONS
The standard 750/760 Series Monitors can be configured with a
combination of available options. Therefore, based upon the
user requirements the electrical installation of 1 or more of the
following options may be required.
2.4.1 220 VAC CONVERSION
STEP 1 Verify that the Facility’s main AC power source is
turned “OFF” or disconnected.
STEP 2 Locate and remove Control board jumpers E1 and E3.
(See Fig. 2-3 and 2-4.)
STEP 3 Using one of the removed jumpers, insert it into jumper
E2’s connection holes as shown in Fig. 2-4.
A typical example is shown above. The relay contacts are shown
in the de-energized position. When energized, the Common
(COM) will disconnect from the Normally Closed (NC) contact
and connect to the Normally Open (NO) contact. Devices may
be operated using either the Normally Open contact or Normally
Closed contact; or both relay contacts may be used to activate
two devices of the same voltage.
Installation
5
2.4.2 0-5 / 0-10 VDC RECORDER BOARD
STEP 1 Place the user-supplied interface cable and water tight
cable restraint into the enclosure’s appropriate access
hole.
STEP 2 Neatly insert cable wires into the Recorder board’s TB1
plus (+) and minus (-) terminal connectors. (See Fig. 2-5).
2.4.3 4-20 mA AND 420D TRANSMITTER BOARDS
STEP 1 Place the user supplied cable and watertight cable
restraint into the enclosure’s appropriate access hole.
STEP 2 Neatly insert cable wires into the 753 Panel board plus
(+) and minus (-) TB1 terminal block connectors as
shown in Fig. 2-6-1 or 2-6-2.
STEP 3 See Section 4.3.5 to calibrate the 4-20mA minimum
and maximum current outputs.
6
Introduction
SECTION 3
Operating Procedures
3.1 GENERAL
This section provides the user with the 750/760 Series Monitor’s
recommended operational checkout procedures. The
illustrations contained in Section 3.2 have been provided to
assist the user in identifying all standard and optionally available
switch and indicator controls.
3.2 SWITCH AND INDICATORS CONTROLS
(Standard on all Models)
“ABOVE/BELOW” Set Point Indicators
The green LED indicator light is “ON” only when the
resistance of the water is “ABOVE” the Monitor’s
internal set point adjustment.
The red LED indicator light is “ON” only when the
resistance of the water is “BELOW” the Monitor’s
Internal set point adjustment.
3.2.1 MODEL 750
“SET POINT” Adjustment Knob
Front panel adjustment knob provides immediate
access for adjusting the Controller’s Set Point setting
and to verify its Full Scale reading.
3.2.2 MODEL 752 AND 753
2 1/2" ANALOG METER (752)
The 752’s 2 1/2” (63 mm) linear analog meter provides a
continuous readout of the water being monitored.
DIGITAL LCD METER (753)
The 753’s 1/2" (13 mm) digital LCD meter provides a
continuous readout of the water being monitored.
“SET POINT CHECK” Switch
When the “SET POINT CHECK” switch is depressed
the internal “Set Point” reading is immediately
displayed on the 752’s analog or 753’s digital display
meter.
3.2.3 MODEL 762
4 1/2" ANALOG METER
The 762’s 4 1/2" (114 mm) linear analog meter
provides a continuous readout of the water being
monitored.
Operating Procedures
7
“3 RANGE” Full Scale Select Switch
A full scale range of 0-20 megohms is selected when
the switch is placed to its RANGE “X 1” position.
A full scale range of 0-2 megohms is selected when the
switch is placed to its RANGE “X .1” position.
A full scale range of 0-0.2 megohms is selected when
the switch is placed to its RANGE “X.01” position.
“3 CELL INPUT” Select Switch (Optional)
Cell 1’s inputs are monitored when switch is placed to
its CELL “1” position.
Cell 2’s inputs are monitored when switch is placed to
its CELL “2” position.
Cell 3’s inputs are monitored when switch is placed to
its CELL “3” position.
3.3 OPERATIONAL CHECKOUT PROCEDURES
The following check-out procedures are used to verify that a
Monitor is operating properly.
3.3.1 MODEL 750
STEP 1 Turn the “SET POINT” adjustment knob to 20 megohm.
The red “BELOW” light should be on indicating that the
water being monitored is below the Set Point.
STEP 2 Turn the “SET POINT” adjustment knob to 0 megohm.
The green “ABOVE” light should be on indicating that
the water being monitored is above the Set Point.
STEP 3 Rotate the Set Point adjustment knob back and forth
and note the reading at which the lights change. Also
note an audible click as the relay picks up and drops
out. This reading corresponds to the actual water purity.
STEP 4 Set the adjustment knob to the desired control point
setting. Check-out is now complete.
3.3.2 MODELS 752, 753, AND 762
STEP 1 On Model 762, set range switch and cell selector
switch (if applicable) to the desired settings.
STEP 2 Observe resistance reading of water being monitored.
STEP 3 With front panel removed, depress “CHECK SET
POINT” switch and observe “SET POINT” on panel
readout. With a small screwdriver, rotate the Set Point
adjustment pot (R31, Fig. 4-1) to above the reading
observed in Step 2. Release “CHECK SET POINT”
switch and observe that the red (below) light is on.
Depress “CHECK SET POINT” switch and adjust Set
Point to below the reading observed in Step 2. Release
“CHECK SET POINT” switch and observe that the
green (above) light is on. Also note the audible click of
the relay as the lights change.
STEP 4 Adjust Set Point to desired setting and replace front
panel. This completes the checkout.
8
Operating Procedures
SECTION 4
Component Identification, Calibration and Preventive Maintenance
4.1 GENERAL
Section 4.2 provides detailed illustrations to assist the user in
identifying a 750/762 Series Monitor’s primary components.
Section 4.3 provides the user with the 750/762 Series Monitor’s
various Calibration procedures.
Section 4.4 provides the user with the Myron L Company’s
recommended Preventive Care.
4.2 PRIMARY COMPONENT IDENTIFICATION
As identified in Section 3, the Monitor’s various switch and
indicator components are mounted directly to the front panel.
The Monitor’s Control board is contained within and mounted to
the back of the enclosure. The 762 Monitor, when equipped with
3 Cell Input option and the 753 Monitor have a second
component board mounted on the back of the front panel.
Component Identificaiton, Calibration and Preventive Maintenance
9
4.3 CALIBRATION PROCEDURES
All 750/760 Series Monitors are calibrated and tested prior to
shipment.
CAUTION!
When performing Calibration procedures, the user must take
extreme care to avoid contacting fuse or any other portions of
the circuit other than the Calibration controls. Failure to do so
could result in damage to equipment and/or property.
4.3.1 METER MECHANICAL ZERO READING
(752 and 762 analog meters only)
STEP 1 Turn OFF the Monitor’s main AC power and verify that
the meter is indicating a zero (0) reading. If the meter
does not indicate a zero (0) reading, proceed to STEP
2.
STEP 2 Remove the meter’s zero adjustment plug to access
the meter’s Mechanical Zero adjustment screw.
STEP 3 Turn screw until meter indicates a zero (0) reading and
then replace the plug.
NOTE:
If it becomes necessary to replace a faulty meter, see Fig. 4-2
for the meter wire/terminal designations.
4.3.2 FULL SCALE CALIBRATION PROCEDURES
The Calibration Module is configured for the specific range being
calibrated. See Fig. 4-3 for proper Calibration Module.
4.3.2.1 MODEL 750
STEP 1 Turn “OFF” the Monitor’s main AC power.
STEP 2 Being careful not to excessively strain cable, unfasten
and remove the Monitor’s front panel.
STEP 3 Remove all five (5) wires from Control board terminal
block TB3 (See Fig. 4-1).
STEP 4 By following the wiring diagram in Fig. 4-3, connect the
Calibrator Module’s lead wires to the Control board’s
TB3 terminal connectors.
STEP 5 Turn “ON” the Monitor’s main AC power.
STEP 6 Set the Set Point adjustment knob to a full scale
reading.
STEP 7 Rotate the main calibration trimmer (R8, Fig. 4-1)
counterclockwise until the red light turns on. Now rotate
clockwise slowly and stop when the green light comes
on. Counting turns, rotate counterclockwise and stop
when the red light turns on. Finally, rotate clockwise 1/2
of the turns counted in the last step. This completes the
calibration procedure.
4.3.2.2 MODELS 752, 753 AND 762
Before attempting to calibrate the Model 752 or 762 analog
meter, refer to Section 4.3.1.
STEP 1 Repeat STEPS 1-4 in Section 4.3.2.1.
NOTE:
If equipped with the 3 Cell Input option, place the Cell select
switch to its “CELL 1” setting and remove the five (5) wires from
Cell 1’s terminal block only.
STEP 2 Turn “ON” the main AC power and verify that the 752
and 762 analog meter or 753 digital display is
indicating a full scale reading. (i.e. a 20 megohm
reading on model 752-1 or a 19.99 megohm reading on
model 753-1.)
NOTE:
If the meter indicates an accurate reading, proceed to STEP 4.
If the meter does not indicate the appropriate reading, proceed
to STEP 3.
STEP 3 Turn the Control board’s R8 adjustment screw (See
Fig. 4-1) until the meter displays the appropriate
reading as indicated in STEP 2.
STEP 4 Remove the Calibrator Module’s lead wires and
reconnect the Cell cable wires as shown in Fig. 2-3.
10
Component Identificaiton, Calibration and Preventive Maintenance
4.3.3 INTERNAL SET POINT ADJUSTMENT
NOTE:
Because the Model 750 is equipped with a standard front panel
“SET POINT” adjustment knob, it does not require an internal
Set Point adjustment setting. Refer to Section 3.3 for procedures
to adjust the 750’s Set Point.
STEP 1 Being careful not to excessively strain cable, unfasten
and remove the Monitor’s front panel.
STEP 2 While simultaneously depressing the “SET POINT
CHECK” switch, turn the Control board’s R31
adjustment screw (See Fig. 4-1) until the desired Set
Point value is indicated on the meter display.
NOTE:
The Monitor’s Set Point setting is based upon the user’s
particular water purity specifications.
STEP 3 After successfully completing STEP 2, remount the
front panel and tightly secure both retaining screws.
4.3.4 0-5 / 0-10 VDC RECORDER BOARD
When properly calibrated to a Monitor’s Full Scale output, the
Recorder interface will provide an adjustable 0-5 through 0-10
VDC.
NOTE:
The Recorder board’s circuitry is not isolated from the Monitor’s
standard Control and Panel board circuitry. Therefore, DO NOT
attempt to connect any user device that could provide a path to
earth ground and/or has an input impedance less than 2000
ohms. Failure to do so may result in faulty operation of the
monitor.
STEP 1 As shown in Fig. 4-5, connect voltmeter probes to the
Recorder board’s TB1 (+) and (-) terminal connectors.
STEP 2 While simultaneously depressing the “SET POINT
CHECK” switch (See Fig. 4-1) turn the Control board’s
Set Point adjust trimmer (R31 ) until the meter displays
the appropriate Full Scale reading.
STEP 3 Next, while still depressing the “SET POINT CHECK”
switch, turn the Recorder board’s R3 Trimmer
adjustment screw (See Fig. 4-5) until the desired full
scale voltage output is indicated on voltmeter.
STEP 4 Reset Set Point to desired setting.
4.3.5 MODEL 753 WITH 4-20 mA OR 4-20D OPTION
NOTE: FOR 420D, PROCEED TO STEP 1.
CAUTION: FOR 4-20mA OPTION ONLY
The proper supply voltage (VDC Supply) and load resistance (R)
must be selected. Failure to do so could result in damage to the
753 optional panel board.
NOTE:
The proper load resistance (in ohms) is found by using the
formula and/or chart as shown below.
Component Identificaiton, Calibration and Preventive Maintenance
11
STEP 1 Set the controls of a test meter to read at least 20 mA
and connect it between the positive terminals of the
Transmitter and Receiver as shown in Fig. 4-7 (4-20
mA option) and Fig. 4-8 (4-20D option).
NOTE: Receiver connected to 420D option should have an
input impedance less than 500 ohms.
STEP 2 Press and hold the “SET POINT CHECK” switch. It
must be depressed during all the following adjustment
steps.
STEP 3 Turn the Set Point trimmer (R31 ) (see Fig. 4-1 ) until
the meter displays a reading of 0.00.
STEP 4 Turn the 4-20 mA Null trimmer (R23) (see Fig. 4-6) until
the test meter indicates 4 mA.
STEP 5 Readjust the Set Point trimmer (R31 ) until the meter
displays 1999 (decimal point omitted).
STEP 6 Turn the 4-20 mA Full Scale trimmer (R20) (see Fig. 4-
6) until the test meter indicates 20 mA.
STEP 7 Repeat STEP 3 through STEP 6, readjusting as
required.
STEP 8 Reset the set point to the desired setting. Release the
“SET POINT CHECK” switch.
4.4 PREVENTIVE CARE
Although designed to minimize operating problems, the Myron L
Company recommends that the following Preventive Care
procedures be observed.
1 Try to prevent exposure to excessive heat and
moisture.
2 The Monitor’s main AC power source must be
protected against excessive voltage spikes.
3 Take care not to damage Monitor during handling.
NOTE:
Daily, weekly or monthly maintenance schedules are based
upon the frequency of use and the severity of the Monitor’s
environment and operating conditions.
STEP 1 Repeat the Monitor’s Check-Out procedures and/or
isolate possible troubleshooting symptoms.
STEP 2 Check all cable connections to ensure that they are
free of moisture and contamination.
STEP 3 Inspect and replace damaged component boards and
cable assemblies.
STEP 4 Remove and clean sensor with soap and water. Rinse
thoroughly.
12
Component Identificaiton, Calibration and Preventive Maintenance
SECTION 5
Appendix A
RESISTIVITY MONITOR CONTROLLERS REPLACEABLE COMPONENTS
DESCRIPTION PART NUMBER
750-1 Control Board 501RM
750-2 Control Board 502RM
750-3 Control Board 503RM
750-5 Control Board 505RM
750 Panel Cable Assembly 50RCA
752-1 Control Board 521RM
752-2 Control Board 522RM
752-3 Control Board 523RM
752 Panel Cable Assembly 52RCA
1
752-1 2
752-2 2 1/2" Analog Meter 522AM
752-3 2 1/2" Analog Meter 523AM
753-1 Control Board 521RM
753-2 Control Board 522RM
753-3 Control Board 523RM
753-1 Digital Display Assembly 531DPM
753-2 Digital Display Assembly 532DPM
753-3 Digital Display Assembly 533DPM
753-1 Digital Display Assembly with 420 Option 531DPM4
753-1 Digital Display Assembly with 420D Option 531DPM4D
753-2 Digital Display Assembly with 420 Option 532DPM4
753-2 Digital Display Assembly with 420D Option 532DPM4D
753-3 Digital Display Assembly with 420 Option 533DPM4
753-3 Digital Display Assembly with 420D Option 533DPM4D
753 Panel Cable Assembly 53RCA
750 Series Enclosure 50EC
750 Series Front Panel with Label, Gasket & Screws 50FP*
762 Control Board 62RM
762 Panel Cable Assembly 62RCA
762 Range Select Cable with switch 62RRSCA
762 4 1/2" Analog Meter 60AM*
760 Series Enclosure 60EC
760 Series Front Panel with Label, Gasket & Screws 60FP*
3 Cell Input Three Range, 3 Cell Input Module
with Harness & Knobs 03
Control Board Fuse
1
0-5 through 10 VDC Output Board 510
Cable For CS10 Cells, Belden 8724 MCRD
Polypropylene Fitting for CS10 Cells 3/4"NPT PPF
PVDF Fitting for CS10 Cells 1/2" NPT PVDF
Stainless Steel Fitting For CS10 Cells 1/2" NPT HPSS
Manual (Installation/Operation/Maintenance) Resistivity Manual
/2" Analog Meter 521AM
/8 AMP AGC 1/8 (All Models) FUSE
IMPORTANT:
WHEN ORDERING ANY
COMPONENT, COMPLETE
INSTRUMENT MODEL
NUMBER MUST BE
SPECIFIED.
* WHEN ORDERING THESE
COMPONENTS, RANGE
MUST ALSO BE SPECIFIED.
Appendix A
WARRANTY
All Myron L Resistivity monitors and sensors have a two year warranty. If any monitor
or sensor fails to function normally, return the faulty unit to the factory prepaid. If, in the
opinion of the factory, failure was due to materials or workmanship, repair or
replacement will be made without charge. A reasonable service charge will be
made for diagnosis or repairs due to normal wear, abuse or tampering. Warranty
is limited to the repair or replacement of monitor or cell only. The Myron L
Company assumes no other responsibility or liability.
Myron L Company, having a policy of continuous product improvement,
reserves the right to make changes in design, specifications and prices without
notice.
Water Q uality Instrum en tation
Acc ur ac y • Reliability • S im pl icity
2450 Impala Drive
Carlsbad, CA 92010-7226 USA
Tel: 1-760-438-2021
Fax: 1-800-869-7668 / 1-760-931-9189
www.myronl.com
8-2-07
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