Magnetic Instrumentation 942B User manual

Created -2013 8431 Castlewood Drive, Indianapolis, IN 46250 USA
[phone] •Fax [phone] .
E-Mail: [e-mail] •www.maginst.com
INSTRUCTION MANUAL
MODEL 942B
MAGNETIZER
Starting with Serial Number 41807

i
IMPORTANT
THE FIXTURE MUST BE CONNECTED BEFORE TURNING ON THE
MAGNETIZER. THE MAGNETIZER WILL NOT FUNCTION UNLESS
A FIXTURE IS PROPERLY CONNECTED.
BEFORE FIRST USE, INSPECT THE MACHINE AND MAGNETIZING
FIXTURE CAREFULLY FOR ANY SIGNS OF SHIPPING DAMAGE.
IF DAMAGE IS EVIDENT NOTIFY THE CARRIER AND MAGNETIC
INSTRUMENTATION, INC. IMMEDIATELY.
THE INSTALLATION, OPERATION AND MAINTENANCE OF THIS
EQUIPMENT SHOULD BE PERFORMED BY QUALIFIED PERSONS
ONLY.
WARNING:
The equipment herein described contains high voltage.
Exercise due care during operation and servicing.
Read safety summary on the following pages.

ii
SAFETY SUMMARY
The following safety precautions must be observed at all times during operation, service
and repair of this product. Failure to comply with these precautions, or with specific
warnings elsewhere in this manual, violates safety standards of design, manufacture, and
intended use of this product. Magnetic Instrumentation, Inc. assumes no liability for
failure to comply with these requirements.
GROUND THE EQUIPMENT
To minimize shock hazard, chassis, cabinets, and equipment racks must be connected to
an electrical ground. AC powered products are equipped with a three-connector power
cable, or equivalent connection on a terminal block. Power cables must be plugged into
an approved three-contact adapter with the grounding wire (green) firmly connected to an
electrical ground (safety ground) at the power outlet. The power jack and mating plug of
power cables provided meet International Electromechanical Commission (IEC) safety
standards. Equipment provided with terminal blocks, operating from either AC or DC is
provided with appropriate means for connecting an electrical safety ground.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE
Do not operate the product in the presence of flammable gases or fumes. Operation of
any electrical equipment in such an environment constitutes a definite safety hazard.
DO NOT OPERATE IN WET OR DAMP AREAS
Do not operate the product in wet or damp areas. Operation of any electrical equipment
in such an environment constitutes a definite safety hazard.
KEEP AWAY FROM LIVE CIRCUITS
Operating personnel must not remove covers. Replacement of components and internal
adjustments must be made by qualified maintenance persons. Disconnect power cable
when replacing components. Under certain conditions, dangerous voltages may exist
even with the power cable disconnected. To avoid injuries always disconnect power and
discharge circuits by grounding before touching them.

iii
DO NOT SERVICE OR ADJUST ALONE
Do not attempt internal service or adjustment unless another person capable of rendering
first aid and resuscitation is present.
DO NOT SUBSTITUTE PARTS OR MODIFY EQUIPMENT
Because of the danger of introducing additional hazards, do not install substitute parts or
perform an unauthorized modification to the equipment. The product may be returned for
service and repair to ensure that safety features are maintained.
DANGEROUS-PROCEDURE WARNING
Throughout this manual, warnings identify potentially dangerous procedures. Instructions
contained therein must be followed.

iv
TABLE OF CONTENTS
I. GENERAL DESCRIPTION 1
A. Optional Accessories 2
B. Safety Procedures 2
II. ELECTRONICS CABINET 3
A. Specifications 3
B. Control Panel Components 3
C. Magnetizing Fixture and Connections 5
III. SET UP INSTRUCTIONS 6
IV. BASIC MAGNETIZER CIRCUIT DESCRIPTION 7
A. Capacitor Charging Circuit 7
B. Discharge Circuit 8
C. Current Bias Supply 8
D. Safety Drain Circuit 8
V. CIRCUIT BOARD DESCRIPTIONS 9
A. General Description of Charge Control Board # 10420270 9
B. Technical Description of Charge Control Board # 10420270 9
C. General Description Power Supply and Relay Board # 10401433 11
D. General Description of ± 15VDC/ ± 24VDC Power Supply # 10401415 11
E. Technical Description of ± 15VDC/ ± 24VDC Power Supply # 10401415 12
F. General Description of Relay Board # 10401416 12
G. Technical Description of Relay Board # 10401416 12
H. Description of 3000 / 300 Divider Board # 10407715 14
I. Technical Description of 3000 / 300 Divider Board # 10407715 14
J. General Description of Parallel SCR Driver Board # 10412049 14

v
K. Technical Description of Parallel SCR Driver Board # 10412049 14
VI. SERVICE AND MAINTENANCE 16
A. General Instructions 16
B. Test Equipment 16
C. Panel Removal 17
D. Adjustments 17
E. Trouble Shooting 17
VII. REPLACEMENT PARTS 19

1
I. GENERAL DESCRIPTION
The Model 942B is a high voltage, capacitive discharge-type magnetizer capable of
saturating all alnico, ferrite, and rare earth magnetic materials. The Model 942B is easily
adapted to a wide variety of production and laboratory magnetizing requirements.
Solid state electronic control circuitry makes this magnetizer a highly reliable, low
maintenance unit. The electronic voltage control circuit prevents the unit from being
discharged before the preset energy level has been reached, thereby preventing
incomplete magnetization.
The Model 942B, with all electronic circuitry and capacitors enclosed in the cabinet, is
also designed for maximum operator safety when used with Magnetic Instrumentation,
Inc. Magnetizing Fixtures. An interlock switch is also mounted withto the panel covering
the connections for the Magnetizing Fixture on the table top. The removal of a
Magnetizing Fixture breaks the incoming power to the control circuits and engages a
safety drain circuit that discharges any energy stored in the capacitor bank.
A 2 terminal twist-lock CHARGEharge INTERLOCKnterlock socket (Figure 6) is
provided on the side of the chassis containing the Magnetizing Fixture transformer
connections on the table top. This allows for connection of an external interlock switch,
engaged with the closure of ,safety shields, or Magnetizing Fixture covers to be sure they
are properly closed before the operator can charge the capacitors.
The Model 942B Magnetizer is available in four basic models, depending upon the
capacitance of the -capacitor bank.
Model
Capacitance
942B-2
200F
942B-4
400F
942B-6
600F
942B-8
800F
Any of these models may be operated from either a 115 VAC or 230 VAC power line.
The power supplyMagnetizer draws a maximum current of 15 Amperes at 115 VAC, and
it charges a 200 µF capacitor bank to 3000 Volts in about 2 seconds. As additional
capacitors are added, the charging time is increased proportionally.
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight
Formatted: Not Highlight

2
A. Optional Accessories
Foot Switch
The Foot Switch option (P/N: 09912508) provides for external control of the cCharge or
mMagnetize functions. Other provisions for remote operation are available.
Temperature Monitor
The Temperature Monitor option (P/N: 09003126) will continuously display the
B. Safety Procedures
This equipment operates at high voltage. All high voltage windings and connections are
enclosed in the cabinet and Magnetizing Fixture housing. Under no circumstances should
these housings or the cabinet be tampered with, or the design altered unless previously
discussed with Magnetic Instrumentation, Inc. Care should be taken that the equipment is
properly grounded. No drilling, tapping, or machine work should be done on the
Magnetizing Fixture housing unless drawings of the internal construction are first
obtained from Magnetic Instrumentation, Inc.
An interlock is mounted to the panel covering the disconnect jacks for the Magnetizing
Fixture. This prevents operation of the machine without the Magnetizing Fixture properly
attached. The high-voltage-disconnect jack and tThe four side panels should only be
removed are provided with interlocks that break the power line. These interlocks should
be blocked only for troubleshooting purposes and then only by an engineer or skilled
technician familiar with this type of equipment and with the danger involved with
working with several hundred microfarads of capacitance charged to 3000 volts.
Caution labels are placed on the equipment in strategic locations, to alert the possible
safety hazards. For maximum safety to the operator, all safety precautions indicated or
implied must be observed.
Formatted: Tab stops: -0.5", Left

3
II. ELECTRONICS CABINET
A. Specifications
Power Source 115 or 230 Volts, 50/60 cycles.
15 Amperes maximum.
Storage Capacitors 200, 400, 600, or 800F, as ordered. Up to
800F may be installed in the cabinet on initial
order, or later as required.
Output Voltage 100 Volts to 3,000 Volts (set by user)
Watt-Second Ratings (Joules) 200F capacitor bank: 900 watt-seconds.
400F capacitor bank: 1800 watt-seconds.
600F capacitor bank: 2700 watt-seconds.
800F capacitor bank: 3600 watt-seconds.
Dimensions and Weight Size: 31" wide x 39" long x 34" high.
Weight: 350 pounds for 200

F unit, 600 pounds for
800

F unit, (Not including Magnetizing Fixture)
B. Control Panel Components
Power ON-OFF Switch
This 15 Amp circuit breaker controls power into the machine.
Fuse
This 1/2 A Slow-Blow 3AG fuse protects the control circuitry.
Power On Light
This red power On / Off light indicates main control power is on.
Panel Meter
The panel meter is a 0 to 1 milli-amp analog meter. It continuously monitors the voltage
of the energy storage capacitor bank. Resistors located on the power supply chassis inside
the machine limit the current to the meter so that it displays 0 to 3000 volts.

4
Voltage Control
This 10 turn potentiometer is used to control the voltage to which the energy storage
capacitor bank is charged. Voltage may be increased by turning the knob clockwise.
Voltage may be decreased by turning off the power-on switch (circuit breaker) or by
initiating the Magnetize function, thereby discharging the capacitor bank through the
fixture. NOTE: When initially setting the voltage it is best to start with the voltage
control knob at minimum and slowly adjust this control clockwise so as not to overshoot
the desired level.
Function Select Switch
Manual (Center Position)
In this mode of operation, manual initiation of both the Charge and Magnetize function is
required. Press the Charge push-button when the white ready-to-charge light is on. The
magnetizer will charge to the voltage level set by the Voltage Control knob and the green
ready-to-magnetize light will turn on. Voltage may be increased by turning the Voltage
Control knob clockwise, or the magnetizer may be discharged by pressing the Magnetize
push-button, provided the green ready-to-magnetize light is illuminated.
Auto Magnetize (Down Position)
In this mode of operation the charge function must be initiated by pressing the Charge
push-button. Upon reaching the voltage level set by the Voltage Control knob the
magnetizer will automatically discharge.
Auto Charge (Up Position)
In this mode of operation the magnetizer will automatically charge to the voltage level set
by the Voltage Control knob and maintain this level until the Magnetize push-button is
pressed. After a period of “off time” the magnetizer will recharge automatically and be
ready for the next cycle.
Charge Light
Illumination of the white light indicates that the magnetizer is ready-to-charge.
Charge Push-Button
The Charge push-button is active only when the magnetizer is ready-to-charge as
indicated by the white light. Pressing the Charge push-button will cause the machine to
charge to the level set by the Voltage Control knob.
External Charge
Directly beneath the Charge push-button is the external charge socket. A dry contact
closure between the 2 terminals will provide a Charge input. (The same as pressing the
Charge push-button.)

5
Magnetize Light
Illumination of the green light indicates that the magnetizer is ready-to-magnetize.
Magnetize Push-Button
The Magnetize push-button is active only when the magnetizer is ready-to-magnetize.
Pressing the Magnetize push-button will cause the machine to discharge the stored energy
into the Magnetizing Fixture.
External Magnetize
Directly beneath the Magnetize pushbutton is the external magnetize socket. A dry
contact closure between the 2 terminals will provide a Magnetize input. (The same as
pressing the Magnetize push-button.)
C. Magnetizing Fixture and Connections
To install a Magnetizing Fixture on the Magnetizer, place the fixture on the table top so
that the pins on the fixture line up with the sockets on the machine. Firmly push the
Magnetizing Fixture straight into the sockets until no air gap is seen and the Fixture
connected interlock switch engages.
IMPORTANT: When connecting a Magnetizing Fixture to the Magnetizer, observe
the connection pins and fixture housing for signs of wear. Connecting a fixture that
has a badly worn housing may pose a hazardous condition to the operator. Make
sure the connections are firmly seated. A poor connection may cause electrical
arcing and/or a low magnetizing field within the fixture.
Magnetizing Fixtures are available from Magnetic Instrumentation, Inc. for use with the
Model 942B Magnetizer. Be sure to follow the suggested operating parameters for each
fixture. Failure to do so may lead to premature failure of the Magnetizer and /or the
Magnetizing Fixture.
NOTE: Due to the high amount of magnetic field produced in the Magnetizing Fixture, it
is important to position the part to be magnetized carefully. A improperly positioned part
will be exposed to a high force moving the part towards the location of maximum field.
Properly locating the part will prevent it from being launched or the possibility of a pinch
point. Part locators for Magnetizing Fixtures are available from Magnetic
Instrumentation, Inc. and are recommended for use with Magnetic Instrumentation, Inc.
Magnetizing Fixtures.

6
III.SET UP INSTRUCTIONS
The following procedure verifies proper operation of the machine.
1. Place the electronics cabinet and Magnetizing Fixture in their final operating location.
2. Connect water source to the Magnetizing Fixture, if required.
3. Connect the Magnetizing Fixture to the electronics cabinet.
4. Set Voltage Control at minimum voltage (full counter-clockwise), and function select
switch to Manual (center) position.
5. Connect AC power cord to a grounded power outlet capable of supplying 15 amps of
continuous power.
6. Turn on electronics cabinet power switch.
7. The fan, the red Power On light, and the white Ready-to-Charge light should come on.
8. Press the Charge push-button. The machine will charge to approximately 100 volts and
the green Ready-to-Magnetize light should come on.
9. Press the Magnetize push-button. The Magnetizer will discharge through the Fixture and
remain idle for approximately 2 to 90 seconds.
10. After this period of off-time the white Ready-to-Charge light will come back on, allowing
the cycle to be reinitiated.
11. Press the Charge push-button and slowly increase the Voltage Control until desired
working voltage is reached.
The machine is now ready to begin processing parts.

7
IV.BASIC MAGNETIZER CIRCUIT DESCRIPTION
A Capacitive Discharge Magnetizer functions by supplying large amounts of energy in a
short time to a Magnetizing Fixture. This magnetizing pulse is milliseconds in length and
is drawn through a discharge switch from the capacitor bank. The capacitor bank is
charged by drawing small amounts of power from the power line over several seconds.
The basic magnetizer consists of a capacitor charging and discharging circuit both of
which are controlled by the logic circuit within the cabinet. A current bias supply is
provided for use with current transformers to make use of the maximum possible flux
change and, therefore, the greatest energy transfer for each size of current transformer.
Block diagram of the Model 942B Magnetizer
Note: All of the major components’ circuit designations in the following section of this
manual are in bold and correspond to the Electrical Schematics sheet 4 and 5 of the
drawing set.
A. Capacitor Charging Circuit
The capacitor charging circuit consists of a Solid State Relay (1SSR), Current Limiting
Inductors (1L and 2L), Step-up Transformers (1T and 4T), Rectifier Boards (1SA and
2SA), and the Capacitor Bank (1C thru 8C). The charging circuit is controlled by the
Solid State Relay providing primary power to the Step-up Transformers through the
Current Limiting Inductors. The secondary voltage of these transformers is rectified by
the Rectifier Boards that are connected directly to the Capacitor Bank.

8
B. Discharge Circuit
The discharge circuit, which provides the magnetizing current, consists of an electrically
matched Parallel SCR Assembly (1SCR), Parallel SCR Driver Board (4PCB), Reverse
Current Blocking Diode Assembly (1DDP), and the Magnetizing Fixture. Provided the
Capacitor Bank is charged to the preset voltage level and the Magnetize function has been
initiated, the Control Circuitry sends a logic signal to the Parallel SCR Driver Board. This
circuit board gates both SCRs with a conditioned signal allowing the stored energy in
Capacitor Bank to discharge through the Magnetizing Fixture. The Reverse Current
Blocking Diode provides a circulation path for the collapsing current preventing any
reverse current from flowing through the Magnetizing Fixture.
C. Current Bias Supply
The current bias supply is used when the Magnetizing Fixture is a Current Transformer.
This supply provides current in the primary windings of the Current Transformer. The
direction of current is reverse to that of the magnetizing current. This is to bias the steel
core if the transformer magnetically so that the greatest possible flux change may be
transferred from primary to secondary. This supply consists of transformer (2T), rectifier
diode (11D), filter capacitor (10C), inductor (3L), and resistor (7R).
D. Safety Drain Circuit
The safety drain circuit will safely discharge the energy storage capacitor bank when the
power to the machine is turned off or the Magnetizing Fixture is disconnected. Once the
discharging of the capacitor bank begins, the machine will not operate until the voltage
has decreased to a safe level. The drain circuit consists of a high voltage vacuum relay
(CRD) and associated capacitors (12C, 13C, and 14C) and diodes (12D and 13D), two
10 K ohm 50 watt resistors (3R and 4R), and lockout relay (1CR). The contacts of the
vacuum relay are normally closed and will connect the 10K resistors across the capacitor
bank when the relay is not powered. The capacitors on the vacuum relay’s coil provide a
delay of about 4 seconds before the relay will turn off so that momentary interruptions of
power will not effect machine operation. Once the draining of the capacitors begins
lockout relay (1CR) engages and its contacts open removing power to the charge push
button.

9
V. Circuit Board Descriptions
The following technical descriptions are for the circuit boards located within the
Magnetizer. See the schematics for complete details.
A. General Description of Charge Control Board # 10427655
This board controls the charging, discharging, and timing of the machine.
The charging circuit uses a comparator IC, and Transistor Logic to control an externally
mounted Solid State Relay. This Solid State Relay is used to control the primary of the
step-up transformers used for charging the capacitor bank.
The discharge timing circuit uses a 3-Timer (IC’s) Chain that is controlled by an external
relay. The timing sequence provides enough time to allow the charge circuit to become
inactive before discharging the capacitor bank. Actual discharge of the capacitor bank is
not performed by this board, but it does provide a logic signal that starts the Parallel SCR
Driver board which in turn gates the SCRs.
B. Technical Description of Charge Control Board # 10427655
Charge Circuit:
The reference voltage from the capacitor bank 0 to -300 vdc, is connected to pin 1 of the
header connector, and is fed through a voltage divider R327 1 Meg ohm and R323 15K
ohm to the inverting input of comparator AR301, pin 3. A reference from voltage control
circuit, pins 23 & 24 of header connector, is fed through R324, 430, to the non-
inverting input of comparator AR301. These two inputs are negative with respect to
circuit and chassis ground. The output of AR301, pin 7, will be low, zero volts, when the
capacitor bank reference voltage is below the level set by the voltage control circuit, or
high, +15V if the capacitor bank is above the level set by the voltage control circuit.
Hysteresis of this comparison is controlled by R325, 200K. Transistor Q308 is used to
buffer and invert the output of AR301.

10
The collector of Q308 feeds two circuits:
1. Q307 inverts the logic level on the collector of Q308. The collector of Q307 is used to
drive Q303 that makes up half of the two transistor “AND” circuit that enables a
magnetize condition. Q303 must be on, signifying the capacitor bank is not charging,
before the collector of Q302 will be allowed to go low upon the initiation of the
magnetize signal (+15V applied to Pin 17 of header connector). This assures that the
capacitor bank is at the correct voltage level and is not charging before allowing the
magnetize or discharge function to be processed.
2. Q308 also drives the circuit that provides the control signal to the Solid State Relay,
(providing primary power to the charging transformers) from Pin 7 of the header
connector. To enable a charge condition, ground (supply common) must be applied to
Pin 6 of the header connector, allowing the collector of Q311 to go low. A low level on
the collector of Q311 turns on Q313 allowing the +24V supply to be seen through R333
and D305 (jumper wire) to Pin 7 of header connector. When Q313 is off the -24V supply
through R334, R333, and D305 (jumper wire) creates a slightly negative potential at Pin 7
of header connector holding the Solid State Relay off. Q309 is used to drive an at-voltage
(ready to magnetize indicator or relay coil) signal. If ground (supply common) is applied
to Pin 8 of the header connector (emitter of Q309), and the -24V supply through a relay
coil or an indicator is applied to Pin 5 of header connector, this coil/indicator will be on
when Q313 is off.
Discharge Circuit:
Pin 17 of the header connector is used to initiate the discharge function. When the
+15VDC supply is applied to Pin 17 of the header connector Q302 will be turned-on and
provided Q303 is on, (signifying the charge circuit is not-active), ground (supply
common) is seen at Pin 12 of header connector. Pin 12 of header connector is used to start
the discharge timing sequence.
When Pin 12 of the header connector goes low, 2 conditions have happened.
1. The capacitor bank has been charged to the preset voltage level and the
charge function is not currently active.
2. A magnetize input signal has been provided.
At the same time Pin 12 of the header connector goes low, Q310 is turned on holding
Q313 (charging transistor) off, disabling the charge function. The 3-Timer Chain IC301,
IC302, IC303 is enabled by Pin 10 of header connector, (Ov on Pin 10 = Disable +15V
on Pin 10 = Enable), and triggered by Pin 19 of header connector (Ov = trigger).

11
Timing sequence:
Provided the timers are enabled, (Pin 10 of header connector at +15V), a low (Ov)
applied to Pin 19 of header connector turns off Q301 allowing C303 to discharge. This
starts timers IC301 and IC 302. IC301 turns on Q304 disabling the charge circuit through
Q310, and maintains the low at Pin 12 of header connector. IC301 also turns on Q305
activating the first half of a two transistor “AND” circuit. IC301’s output Pin 3 will
remain active (+15V) for the entire discharge cycle. This time is adjustable by the RC
time constant of C301 220µfd, R307 10K, and potentiometer POT301. This timer
remaining active is what provides the delay between the discharge of the machine and the
ability to recharge for the next cycle. Timer IC302 is used to provide a delay between the
start of the discharge cycle and actual discharge of the capacitor banks to allow the charge
circuit enough time to shut-off (approx.: 100ms). When IC302’s output returns to a low
(timing cycle completed) C306 discharges and provides a trigger to IC303. Upon seeing
the trigger the output of IC303 goes high (+15V) and turns on the second half of the
“AND” circuit Q306. This allows the collector of Q305 to go low providing a low
impedance path to ground (supply common) to be seen at Pin 2 of the header connector.
Pin 2 of the header provides the start signal used to trigger the circuit board that drives the
discharge device (typically an SCR driver board).
C. General Description Power Supply and Relay Board # 10401433
This board is a combination of two boards that can be separated from one another. When
not separated, the board is part number 10401433. Once separated the two boards become
a # 10401415 and # 10401416. All references to the header connector pin numbers of #
10401415 should be considered 1CN, and all references to the header connector pin
numbers of 10401416 should be considered 2CN.
D. General Description of ± 15VDC/ ± 24VDC Power Supply # 10401415
To provide normal operation for this board an external transformer (36 VAC center-
tapped) must be used. This board is used to supply unregulated ±24 VDC and regulated
±15 VDC. The +15 output is adjustable from approximately 6.5 VDC to 16 VDC and
must be adjusted prior to use. The -15 output is not adjustable.

12
E. Technical Description of ± 15VDC/ ± 24VDC Power Supply # 10401415
The power supplied to this board must be provided by an externally mounted transformer
connected to Pins 5 and 6, center tap to Pin 7 or 8, of header connector. This transformer
should provide 18 VAC between Pins 5 and 7 or 8, and 18 VAC between Pins 6 and 7 or
8, 36 VAC should be seen between Pins 5 and 6. The center tap of this transformer is
connected to circuit common. Full wave bridge rectifier DB 201 (1 amp max) serves to
provide unregulated +24 VDC and -24 VDC with respect to circuit common
approximately 50 VDC may be from the negative to the positive side of this bridge. The
+24 VDC output (Pin 4 of header connector) is filtered by C202 (2200µfd) and the -24
VDC output (Pin 3 of header connector) is filtered by C203 (500 µfd). The +24 VDC
output also supplies the input to adjustable regulator IC 201 (1.5 amp max) to provide the
+15 VDC output (Pin 1 of header connector). This regulator may be adjusted from
approximately +6.5 VDC +16 VDC (with respect to circuit common) by POT 201 (500 
1 turn). The -24 VDC output supplies the input to regulator IC 202 used to provide the
-15VDC output Pin 2 of header connector. The ± 24 VDC outputs are non-regulated and
will vary with input AC voltage and/or load. The ± 15 VDC outputs are regulated and
should not vary more than ± 0.5 volts. The limiting factor for available output current
may be dictated by the external transformer connected to this power supply. All of the
components used are rated for a minimum of 1 Amp. However, if the transformer used is
rated for less than 1 Amp, the rating of the transformer will dictate available output
current.
F. General Description of Relay Board # 10401416
This board houses 2-4 Pole double throw 24 VDC (coil) relays. Each contact set on both
relays is electrically isolated from each other.
G. Technical Description of Relay Board # 10401416
Relay CR201’s coil and contacts run to Pins 15 through 28 of the header connector. Relay
CR202’s coil and contacts run to Pins 1 through 14 of the header connector. A diode is
mounted in parallel with each relay coil to eliminate an induced surge generated by
turning off the inductive load of the relay’s coil. This diode also dictates the polarity with
which each coil is powered. CR202’s coil is connected to Pins 1 and 3 of the header
connector. The diode in parallel with CR202 is D203. The anode of D203 is connected
to Pin 1, and the cathode of D203 is connected to Pin 3 of the header connector. The
polarity of the power used to turn on CR202 must make the diode (D203) reversed bias.
(Pin 1 of the header connector must be negative with respect to Pin 3 of the header
connector.)

13
The contacts of CR202 are as follows:
Header Connector
Contact
Pin Number
Configuration
7
Normally Open (N.O.)
5
Common (C.) (shared by Pins 7 & 8)
8
Normally Closed (N.C.)
6
N.O.
4
C. (shared by Pins 6 & 9)
9
N.C.
13
N.O.
2
C. (shared by Pins 13 & 10)
10
N.C.
12
N.O.
14
C. (shared by Pins 12 & 11)
11
N.C.
CR201’s coil is connected to Pins 26 & 28 of the header connector. The diode in parallel
with CR201 is D202. The anode of D202 is connected to Pin 26 and the cathode of D202
is connected to Pin 28 of the header connector. The polarity of the power used to turn on
CR201 must make the diode (D202) reversed bias. (Pin 26 of the header connector must
be negative with respect to Pin 28 of the header connector)
The contacts of CR201 are as follows:
Header Connector
Contact
Pin Number
Configuration
22
Normally Open (N.O.)
24
Common (C) (shared by Pins 22 & 21)
21
Normally Closed
23
N.O.
25
C. (shared by Pins 23 & 20)
20
N.C.
16
N.O.
27
C. (shared by Pins 16 & 19)
19
N.C.
17
N.O.
15
C. (shared by Pins 17 & 18)
18
N.C.