CleaverBrooks CB780 User manual

$25.00
Cleaver-Brooks
CB780/CB784
Operation and Maintenance Manual
DIVISION OFAQUA-CHEM, INC.
750-166

TO: Owners, Operators and/or Maintenance Personnel
This manual presents information that will help to properly operate and care for the equipment. Study its contents carefully. The unit
will provide good service and continued operation if proper operating and maintenance instructions are followed. No attempt should
be made to operate the unit until the principles of operation and all of the components are thoroughly understood. Failure to follow all
applicable instructions and warnings may result in severe personal injury or death.
It is the responsibility of the owner to train and advise not only his or her personnel, but the contractors' personnel who are servicing,
repairing, or operating the equipment, in all safety aspects.
Cleaver-Brooks equipment is designed and engineered to give long life and excellent service on the job. The electrical and mechanical
devices supplied as part of the unit were chosen because of their known ability to perform; however, proper operating techniques and
maintenance procedures must be followed at all times. Although these components afford a high degree of protection and safety,
operation of equipment is not to be considered free from all dangers and hazards inherent in handling and firing of fuel.
"Automatic" features included in the design do not relieve the attendant of any responsibility. Such features merely free him of
certain repetitive chores and give him more time to devote to the proper upkeep of equipment.
It is solely the operator's responsibility to properly operate and maintain the equipment. No amount of written instructions can replace
intelligent thinking and reasoning, and this manual is not intended to relieve operating personnel of the responsibility for proper
operation.
Operating controls will normally function for long periods of time. Do not become lax in daily or monthly testing, assuming that
normal operation will continue indefinitely. Malfunctions of controls lead to uneconomical operation and damage and, in most cases,
these conditions can be traced directly to carelessness and deficiencies in testing and maintenance.
Operation of this equipment by the owner and his operating personnel must comply with all requirements or regulations of his
insurance company and/or other authority having jurisdiction. In the event of any conflict or inconsistency between such requirements
and the warnings or instructions contain herein, please contact Cleaver-Brooks before proceeding.

Cleaver-Brooks
CB780/CB784
Operation and Maintenance Manual
Please direct purchase orders for replacement manuals to your local
Cleaver-Brooks authorized representative
Manual Part Number 750-166
6/95
Rev 10/95
Printed in U.S.A.
© Aqua-Chem, Inc., 1995

CONTENTS
Section 1 – Installation and Operating Instructions
Section 2 – SystemAnnunciation Diagnostics and Troubleshooting

750-166 1-1
Section 1 - CB780/CB784
Installation and Operating Instructions
—Flame signal strength.
—Expanded annunciator status.
—Total cycles of operation.
—Total hours of operation.
—Fault history of six most recent faults:
• Cycles of operation at time of fault.
• Expanded annunciator data at time of fault.
• Fault message and code.
• Hours of operation at time of fault.
• Sequence status at time of fault.
• Sequence time at time of fault.
—Diagnostic information:
• Device type.
• Flame amplifier type.
• Flame failure response time.
• Manufacturing code.
• On/Off status of all digital inputs and outputs.
• Selected prepurge time.
• Software revision and version of CB780/CB784 and
Keyboard Display Module.
• Status of configuration jumpers.
• Status of Run/Test Switch.
CONTENTS
Specifications ............................................................... 2
Principle Technical Features ...................................... 6
Safety Provisions ......................................................... 7
Installation ................................................................... 9
Wiring ........................................................................ 11
Assembly .................................................................... 15
Operation ................................................................... 18
Static Checkout .......................................................... 25
Checkout .................................................................... 27
Troubleshooting ......................................................... 34
—Interlock check.
—Closed loop logic test.
—Dynamic Auto-Check.
—Dynamic input check.
—Dynamic safety relay test.
—Dynamic self-check logic.
—Expanded safe-start check.
—High Fire Purge Switch test.
—Internal hardware status monitoring.
—Low Fire Start Switch test.
—Tamper resistant timing and logic.
■Access for external electrical voltage checks.
■Application flexibility.
■Communication interface capability.
■Dependable, long-term operation provided by microcom-
puter technology.
■First-outannunciationandsystem diagnosticsprovided by
a2 rowby20 columnVacuumFluorescentDisplay(VFD)
located on the Keyboard Display Module.
■First-out expanded annunciation with 26 Light Emitting
Diodes (LEDs) for limits and interlocks (optional).
■FivesequenceinformationLightEmittingDiodes(LEDs).
■Five function Run/Test Switch.
■Interchangeable plug-in flame amplifiers.
■Local or remote annunciation of operation and fault
information.
■Nonvolatilememory forretaininghistoryfilesand sequenc-
ing status after loss of power.
■Remote reset (optional).
■Report generation (optional).
■Burner controller data:
—Sequence status.
—Sequence time.
—Hold status.
—Lockout/alarm status.
The Cleaver-Brooks CB780/CB784 is a microprocessor
based integrated burner control for automatically fired
gas, oil, or combination fuel single burner applications. The
CB780 consists of a Relay Module and Keyboard Display
Module. The CB784 consists of the Relay Module only. The
Keyboard Display Module is optional with the CB784. Sub-
base, Amplifier, and Purge Card are required to complete the
system. Options include Personal Computer Interface, Control
Bus, Remote Display Mounting, First-Out Expanded Annun-
ciator and Combustion System Managment software.
The CB780/CB784 is programmed to provide a level of
safety, functional capability and features beyond the capacity
of conventional controls.
Functions provided by the CB780/CB784 include auto-
matic burner sequencing, flame supervision, system status
indication, system or self-diagnostics and troubleshooting
.
■Safety features:

1-2 750-166
Terminal No. Description Ratings
G Flame Sensor Ground
1
Earth G Earth Ground
1
L2(N) Line Voltage Common
3 Alarm 120 Vac, 1A pilot duty.
4 Line Voltage Supply (L1) 120 Vac (+10/-15%), 50 or 60 Hz (±10%).
2,5
5 Burner Motor 120 Vac, 9.8AFL, 58.8ALR (inrush).
6 Burner Controller and Limits 120 Vac, 1 mA.
7 Lockout/Running Interlock 120 Vac, 9A.
8 Pilot Valve/Ignition 120 Vac, 4.5A ignition and 50VA pilot duty.
3
9 Main Fuel Valve 120 Vac, 2A pilot duty.
4
10 Ignition 120 Vac, 4.5A Ignition.
3
F(11) Flame Sensor 60 to 220 Vac, current limited.
12 Firing Rate High Fire 120 Vac, 75 VA pilot duty.
13 Firing Rate Common 120 Vac, 75 VA pilot duty.
14 Firing Rate Low Fire 120 Vac, 75 VA pilot duty.
15 Firing Rate Modulate 120 Vac, 75 VA pilot duty.
16 Unused
17 Unused
18 Low Fire Switch Input 120 Vac, 1 mA.
19 High Fire Switch Input 120 Vac, 1 mA.
20 Preignition Interlock Input 120 Vac, 1 mA.
21 Interrupted/Pilot Valve/First Stage Oil Valve 120 Vac, 2A pilot duty.
22 Shutter 120 Vac, 0.5A.
CB780/CB784
SPECIFICATIONS
TABLE 1—TERMINAL RATINGS.
Specifications
ELECTRICAL RATINGS, see Table 1:
Voltage and Frequency: 120 Vac (+10/-15%), 50 or
60 Hz (+/- 10%)5.
Keyboard Display Module: 13 Vdc peak full wave
rectified (+20/-15%).
Power Dissipation:
CB780/CB784: 10W maximum.
Display Module: 3W maximum.
Maximum Total Connected Load: 2000 VA.
Fusing: Total Connected Load: 20A maximum, type
FRN or equivalent.
1The CB780/CB784 must have an earth ground providing a connection between the subbase and the control panel or the equipment.
Theearthgroundwiremustbecapableofconductingthecurrenttoblowthe20Afuse(orbreaker)ineventofaninternalshortcircuit.
The CB780/CB784 needs a low impedance ground connection to the equipment frame which, in turn, needs a low impedance
connection to earth ground. For a ground path to be low impedance at RF frequencies, the connection must be made by minimum
length conductors having maximum surface areas. Wide straps or brackets are preferred rather than leadwires. Be careful to ensure
thatmechanicallytightened jointsalongthe groundpath, such aspipe orconduitthreads orsurfacesheld togetherwith fasteners,are
free of nonconductive coatings and are protected against mating surface corrosion.
22000 VA maximum connected load to CB780/CB784 Assembly.
3Can also be 120 Vac, 1A pilot duty.
4Can also be 65 VA pilot duty with motorized valve, 1150 VA inrush, 460 VA open, 250 VA hold.
5Operating frequency chosen by CB780/CB784 selection.

750-166 1-3
CB780/CB784
SPECIFICATIONS
ENVIRONMENTAL RATINGS:
Ambient Temperature:
Operating: -40°F to 140°F.
Storage: -40°F to 150°F.
Humidity: 85% RH continuous, noncondensing.
Vibration: 0.5G environment.
DIMENSIONS: Refer to Figs. 1 and -2.
WEIGHT:
CB780/CB784: 1 pound 10 ounces, unpacked.
Keyboard Display Module: 4 ounces, unpacked.
IMPORTANT: Flame Detection System available for use
with CB780/CB784. To select your Plug-in Flame
Signal Amplifier and matching Flame Detector, see
Table 2.
TABLE 2—FLAME DETECTION SYSTEMS (FIGS. 3, 4, 5).
aThe 817-1743 Flame Detector should be used only on burners that cycle on-off at least once every twenty-four hours. Appliances with
burners that remain on for twenty-four hours continuously or longer should use the 817-1121 Flame Detector with the 833-2741 Amplifier
as the ultraviolet flame detection system.
bCircuitry tests all electronic components in the flame detection system (amplifier and detector) 12 times a minute during burner operation
and shuts down the burner if the detection system fails.
cCircuitry tests the flame signal amplifier 12 times a minute during burner operation and shuts down the burner if the amplifier fails.
TABLE 3—SEQUENCE TIMING FOR NORMAL OPERATION.2
Flame
Establishing
Period Post
Purge Interlock Firing Rate Energy Saving Approval Code
Device Initiate Standby Purge Pilot Main Run Timing Circuits Circuit Prepurge Bodies
CB 780/
CB 784 10 sec * ** 4 or 10 sec 10 or 15 sec
1
* 15 sec Preignition,
Lockout,
High and
Low Fire
4-wire
modulating No FM/IRI Modulating
* STANDBY and RUN can be an infinite time period.
** PURGE will be determined by which purge card is selected.
1The MFEP will be determined by which terminal is used, see Figs. 7 and 18.
2The operating sequence of the CB780 and CB784 Relay Modules are identical. The only difference between the Relay
Modules is that the Keyboard Display Module is standard with the CB780 and optional with the CB784.
APPROVAL BODIES:
Underwriters Laboratories Inc. listed, File No. MP268,
Guide No. MCCZ.
Canadian Standards Association certified, LR9S329-3.
Factory Mutual approved, Report No. JI1V9A0.AF.
IRI acceptable.
FederalCommunicationsCommission,Part15,ClassB—
Emissions.
Plug-In Flame Amplifiers Applicable Flame Detectors
Type Color Self-Checking Part Number
Flame
Failure
Response
Time Fuel Type Part Number
Infrared Red No 833-2722 3 sec. Gas, oil,
coal Infrared (Lead Sulfide) 817-1742
Dynamic AMPLI-
CHECK™ 833-2723
c
Gas, oil,
coal Infrared (Lead Sulfide) 817-1742
Ultraviolet Purple No 833-2724 Gas, oil Ultraviolet 817-1743
a
Ultraviolet
Self-Check Green Dynamic Self- Check 833-2741
b
Gas, oil,
coal Ultraviolet (Purple
Peeper)
817-1121
Dynamic Auto-Check

1-4 750-166
CCB780/CB784
SPECIFICATIONS
MOUNTING: 833-2725 for panel mount.
REQUIRED COMPONENTS:
CB780: 120 Vac/60 Hz, 833-2718.
CB780: 120 Vac/50 Hz, 833-2719.
CB784: 120 Vac/60 Hz, 833-2720.
CB784: 120 Vac/ 50 Hz, 833-2721
Plug-in Flame Signal Amplifier, see Table 2.
Plug-in Purge Timer Cards: selectable:
833-2730 30 sec.
833-2731 60 sec.
833-2732 90 sec.
833-2733 2-1/2 min.
NOTE: The CB780 and CB784 are identical except for the
Keyboard Display Module which is standard with the
CB780 and optional with the CB784.
ACCESSORIES:
Optional:
Control Bus—part no. 833-2729. Provides
communication and remote reset capabilities on
CB784; remote display capabilities on CB780
and CB784.
CB783 Expanded Annunciator—part no. 833-2726.
Keyboard Display Module—part no. 833-2727.
(Standard on CB780; optional on CB784.)
Remote Mounting Kit for the Keyboard Display,
NEMA 4—part no. 833-2740.
Tester—part no. 626-5050.
BURNER CONTROL
POWER
PILOT
FLAME
MAIN
ALARM
RESET
SCROLL MODE
SAVE
5
(127)
5 (127)
M7399
REMOVE ONLY FOR TERMINAL TEST ACCESS.
1
1
5-1/4 (133)
Fig. 1—Mounting dimensions of CB780/CB784 Relay Module and 833-2725 Subbase, in inches (mm)

750-166 1-5
CB780/CB784
SPECIFICATIONS
COLLAR WITH 1/2-14 NPSM
INTERNAL THREADS
4 (102) 6 FOOT (1.83 METER)
LEADWIRES (2)
M7419
3-1/2 (89)
1-1/16
(27)
M7405
SCROLL MODE
SAVE
BURNER CONTROL
,

,



4-27/32 (123)
2-3/4
(69)
5/32
(4) 29/32
(23)
5/16
(8)
4-3/32 (104)
19/32
(15) 1-1/4
(32) 1-1/32
(26)
1-15/16
(49) 2-5/16 (58)
29/32
(23)
5/32 (4)
1/2
(13)
2-1/32
(52)
15/
32
(12)
13/
32
(11)
3-7/8 (99)
7/16 (11)
5/15
(8)
817-1742
817-1743
APERTURE
BUSHING WITH
MAGNIFYING LENS COLLAR, 3/4-14 NPSM
INTERNAL THREADS
3/4-14
NPSM 3/4-14 NPSM INTERNAL
THREADS
HEAT BLOCKCELL MOUNT
M1982A
2 LEADS IN A
48 INCH [1.2 METER]
FLEXIBLE CONDUIT
2-3/4
(70)
1-1/4
(32)
1-5/8 (41)
1-1/16 (27)
1-1/4
(32)
833-2727
(Standard with CB780, optional with CB784)
817-1121
MOUNTING FLANGE
1/2–14 NPSM
LEADWIRES FACEPLATE
3/4–14 NPT
M1962A
3-3/4
(95)
7-7/32
(183)
5-1/8 (130)
3-7/16
(87)
5-1/4 (133)
Fig. 2—Mounting dimensions of Keyboard
Display Module, in inches (mm).
Fig. 3—Ultraviolet Self-Check detector.
Fig. 4—Ultraviolet detector.
Fig. 5—Infrared detector.

1-6 750-166
CB780/CB784
PRINCIPAL TECHNICAL FEATURES
PrincipalTechnical Features
The CB780/CB784 provides all customary flame safe-
guardfunctionswhileprovidingsignificantadvancementsin
the areas of safety, annunciation and system diagnostics.
SAFETY SHUTDOWN (LOCKOUT) OCCURS IF:
1. INITIATE Period
a. Purge card is not installed or removed.
b. Purge card is bad.
c. Configuration jumpers were changed (after
200 hours).
d. AC line power errors, see Operation.
e. Four minute INITIATE period is exceeded.
2. STANDBY Period
a. Flame signal is present after 40 seconds.
b. Preignition Interlock is open an accumulative time
of 30 seconds.
c. Interlock check feature is enabled and the Inter-
lockString (includingtheairflowswitch) is closed
for 120 seconds with controller closed.
d. Ignition/pilot valve/intermittent pilot valve termi-
nal is energized.
e. Main valve terminal is energized.
f. Internal system fault.
g. Purge card is not installed or removed.
h. Purge card is bad.
3. PREPURGE Period
a. Preignition Interlock opens anytime during
PREPURGE.
b. Flamesignaldetected afterfirstten secondsduring
PREPURGE.
c. HighFireSwitchfailstoclosewithinfourminutes,
fifteensecondsafterfiringratemotoriscommanded
todrivetohighfire position at start ofPREPURGE.
d. LowFireSwitchfails to closewithinfourminutes,
fifteensecondsafterfiringratemotor is commanded
to drive to low fire position at end of PREPURGE.
e. LockoutInterlockdoesnotclose within10seconds.
f. Lockout Interlock opens during PREPURGE.
g. Ignition/pilot valve/intermittent pilot valve termi-
nal is energized.
h. Main valve terminal is energized.
i. Internal system fault.
j. Purge card is removed.
k. Purge card is bad.
4. PILOT FLAME ESTABLISHING Period (PFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens.
c.Ignition/pilotvalve/intermittentpilotvalveterminal
is not energized.
d. Early Spark Termination terminal is energized af-
ter five seconds.
e. No flame is present at end of PFEP.
f. Internal system fault.
g. Purge card is removed.
h. Purge card is bad.
5. MAIN FLAME ESTABLISHING Period (MFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens.
c. Ignition/pilot valve/intermittent pilot valve termi-
nal is not energized.
d. Main valve terminal is not energized.
e. No flame is present at end of MFEP.
f. Internal system fault.
g. Purge card is not installed or removed.
h. Purge card is bad.
6. RUN Period
a. No flame is present.
b. Lockout Interlock opens.
c. Main valve terminal is not energized.
d. Internal system fault.
e. Purge card is not installed or removed.
f. Purge card is bad.
7. POSTPURGE Period
a. Preignition Interlock does not close within five sec-
onds or opens after five-second time period.
b. Ignition/pilot valve/intermittent pilot valve termi-
nal is energized.
c. Main valve terminal is energized.
d. Internal system fault.
e. Purge card is removed.
f. Purge card is bad.

750-166 1-7
CB780/CB784
SAFETY PROVISIONS
Safety Provisions
DYNAMIC SELF-CHECK SAFETY CIRCUIT
The microcomputer tests itself and related hardware
whileatthesametime the safety relaysystemteststhemicro-
computer operation. If a microcomputer or safety relay
failure occurs and does not allow proper execution of the
self-check routine, safety shutdown will occur and all safety
critical loads will be de-energized.
EXPANDED SAFE-START CHECK
Theconventionalsafe-startcheck,whichpreventsburner
start-up if flame is indicated at start-up, is expanded to
include a flame signal check during STANDBY, a preigni-
tion interlock check, an interlock check, and a safety critical
load check.
HIGH FIRE PURGE AND LOW FIRE START
SWITCH TESTS
High Fire Purge Switch Test examines the Purge Posi-
tion Interlock Switch at the moment the firing rate motor is
commanded to the high fire position. If the switch is by-
passed, welded or otherwise closed prematurely, the system
will automatically add 30 seconds to allow additional drive
time for the firing rate motor to reach or near the open
position before starting the purge timing; otherwise, purge
timing starts when the High Fire Switch is closed. This
switch will also cause a hold (four minutes, fifteen seconds)
condition when the switch is open before purge or opens
during purge. The CB780/CB784 will lockout and annunci-
ate an alarm if the switch fails to close within the hold time
period.
Low Fire Start Switch Test examines the Low Fire Start
Switch at the moment PREPURGE is completed. If the
switchis bypassed,welded orotherwise prematurelyclosed,
the system automatically adds 30 seconds to allow the firing
rate motor additional time to reach or near the low fire start
position before ignition trials; otherwise, ignition trials start
aftertheLowFireSwitch closes.Thetestalsois usedtoprove
that the firing rate motor is at low fire position throughout
the ignition trial period. This switch will also cause a hold
(four minutes, fifteen seconds) condition if the switch opens
after purging is complete. The CB780/CB784 will lockout
andannunciate analarmiftheswitchfailstoclosewithinthe
hold time period.
INTERNAL HARDWARE STATUS MONITORING
The CB780/CB784 checks the purge card for correct
parity to prevent purge timing shifts and circuitry failures. It
also analyzes the integrity of the configuration jumpers and
internal hardware. The POWER LED blinks every four
seconds, signifying an internal hardware check.
CLOSED LOOP LOGIC TEST
The test verifies the integrity of all safety critical loads,
terminals 8, 9, 10 and 21. If the loads are not energized
properly; i.e., the main valve terminal is powered during
PREPURGE,theCB780/CB784willlockoutonsafetyshut-
down. The CB780/CB784 must react to input changes but
avoid the occurrence of nuisance shutdown events. Signal
conditioningisappliedtolinevoltage inputstoverifyproper
operationinthepresenceofnormal electricallinenoisesuch
as transient high voltage spikes or short periods of line
dropout.Signalconditioningistolerantofsynchronousnoise
(linenoiseeventsthatoccuratthesametimeduringeachline
cycle).
DYNAMIC AUTO-CHECK
Dynamic Auto-Check circuitry tests the flame signal
amplifierduringburneroperationandshutsdowntheCB780/
CB784 if the flame amplifier fails.
DYNAMIC FLAME AMPLIFIER AND SHUTTER
CHECK
Self-checkingcircuitrytestsallelectroniccomponentsin
the flame detection system and amplifier 10 to 12 times per
minute and shuts down the CB780/CB784 if the detection
system fails.
DYNAMIC INPUT CHECK
All system input circuits are examined to verify that the
CB780/CB784 is capable of recognizing the true status of
external controls, limits and interlocks. If any input fails this
test, a safety shutdown occurs and the fault is annunciated.
DYNAMIC SAFETY RELAY TEST
Checks the ability of the dynamic safety relay contacts to
open and close. It also verifies that the safety critical loads,
terminals8,9,10and21,canbede-energized,asrequired,by
the Dynamic Self-Check logic.

1-8 750-166
CB780/CB784
SAFETY PROVISIONS
MANDATORY PURGE
If lockout occurs after the initiation of ignition trials,
(or at anytime during a sequence when the fuel valves may
have been energized), a mandatory POSTPURGE period is
imposed.
OFF CYCLE (STANDBY OR PREPURGE) FLAME
SIGNAL CHECK
The flame detection subsystem (flame detector and am-
plifier) is monitored during STANDBY. If a flame simulat-
ing condition or an actual flame exists, a system hold occurs
and start-up is prevented. If the flame signal exists at any
time after the first 40 seconds of STANDBY, a safety shut-
downwill occurandbeannunciated.Ashutter-checkampli-
fier and self-checking detector are energized for the first
40 seconds during STANDBY and the last two seconds
before exiting STANDBY. If a flame exists, a safety shut-
down occurs. An Auto-Check Amplifier is energized con-
tinually through STANDBY and PREPURGE to detect any
possibility of a runaway detector or a flame. If either situa-
tionhappens,asafetyshutdownoccurs.Astandardamplifier
is energized continually through STANDBY and
PREPURGE. If either situation happens, a safety shutdown
occurs.
PREIGNITION OUTPUT CIRCUIT CHECK
At the end of PREPURGE, the Dynamic Safety Relay
operationischecked.Also,allsafetycriticalloads,terminals
8, 9, 10 and 21 are checked to verify the terminals are not
powered.Ifthe DynamicSafetyRelayoperation isfaulty,or
if any of the safety critical loads are powered, safety shut-
down occurs and is annunciated.
TAMPER RESISTANT TIMING AND LOGIC
Safety and logic timings are inaccessible and cannot be
altered or defeated.
VERIFIED SPARK TERMINATION
The ignition terminal is monitored to verify early spark
termination(fiveseconds ignitionandpilot andfiveseconds
pilot only).
FIRST-OUT ANNUNCIATION AND
SELF-DIAGNOSTICS
Sequence Status Lights (LEDs) provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM. The green POWER LED
blinks every four seconds to signify the CB780/CB784
hardware is running correctly.
Multi-function Keyboard Display Module (standard with
CB780, optional with CB784) shows elapsed time during
PREPURGE,PILOTIGN, MAINIGN,andPOSTPURGE.
As an additional troubleshooting aid, it provides sequence
timing, diagnostic information, historical information and
expanded annunciator information when a safety shutdown
or hold or normal operation occurs.
First-out Annunciation reports the cause of a safety shut-
down or identifies the cause of a failure to start or continue
the burner control sequence with an English text and num-
beredcodeviatheKeyboardDisplayModule. Itmonitorsall
field input circuits, including the Flame Signal Amplifier
andFiringRatePositionSwitches.Thesystemdistinguishes
118 modes of failure and detects and annunciates difficult-
to-find intermittent failures.
Self-Diagnostics adds to the First-out Annunciation by
allowing the CB780/CB784 to distinguish between field
(external device) and internal (system related) problems.
Faults associated within the flame detection subsystem,
CB780/CB784 or plug-in Purge Card, are isolated and re-
ported by the Keyboard Display Module. See the Diagnos-
tics and Troubleshooting section of the CB780/CB784 Op-
erationandMaintenanceManual,ManualNumber750-166.
INTERLOCK REQUIREMENTS
The following interlock inputs are provided:
Low Fire Interlock
This interlock verifies the firing rate motor is in the low
fire position before and during ignition trials.
High Fire Interlock
This interlock verifies the firing rate motor is in the high
fire position prior to and during PREPURGE.
Lockout Interlock
This interlock (ILK) input signifies a Lockout Interlock.
If the Lockout Interlock is open for more than ten seconds
into PREPURGE, the CB780/CB784 will lockout. After
enteringPREPURGE,iftheLockoutInterlockopens during
the first ten seconds, the purge timer will be reset. This
providesacontinuous PURGEtooccur withoutinterruption
before the Pilot Flame Establishing Period. If a Lockout
Interlock opens anytime after ten seconds into PURGE,
during the Ignition Trials or Run, it causes a lockout.
A typical Lockout Interlock string contains an airflow
switch (see Fig. 7). The Interlock Check is a site configur-
able option (see Table 7). If this feature is enabled, the
CB780/CB784 will lockout after 120 seconds whenever
control terminal 6 is energized, and the Lockout Interlock
string(includingairflowswitch)isclosedduringSTANDBY.
Preignition Interlock
The Preignition Interlock input is typically connected to
proof-of-closure switches for fuel valve(s). The Preignition
Interlock must be energized throughout PREPURGE. If the
Preignition Interlock opens during STANDBY, it causes a
hold (30 seconds). The CB780/CB784 will lockout if the
interlockdoesnotclosewithin30secondsduringSTANDBY.
If the Preignition Interlock opens during PREPURGE, it
willlockout.IfthePreignition Interlock is open afterfivesec-
onds into POSTPURGE, the CB780/CB784 will lockout.
ThePreignitionInterlockisignored duringtheignition trials
state and during RUN.

750-166 1-9
WARNING
FIRE OR EXPLOSION HAZARD
CAN CAUSE PROPERTY DAMAGE,
SEVERE INJURY, OR DEATH.
To prevent possible hazardous burner operation,
verification of safety requirememts must be per-
formed each time a control is installed on a burner.
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and
markedon the product tomakesurethe product issuitable
for the application.
3. Installer must be a trained, experienced, flame safe-
guard service technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
CAUTION
1. Disconnect the power supply before beginning
installation to prevent electrical shock, equip-
mentandcontrol damage.Morethanonepower
supply disconnect may be involved.
2. Wiringconnections for theCB780/CB784are
unique; therefore, refer to Figs. 6, 7, 8 or 9 or
the correct Specifications for proper subbase
wiring.
3. Wiring must comply with all applicable codes,
ordinances and regulations.
4. Wiring,whererequired,mustcomplywithNEC
Class 1 (Line Voltage) wiring.
5. LoadsconnectedtotheCB780/CB784mustnot
exceed those listed on the CB780/CB784 label
or the Specifications, see Table 1.
6. Limits and interlocks must be rated to simulta-
neously carry and break current to the ignition
transformer,pilotvalve,andmainfuelvalve(s).
7. Allexternaltimersmustbe listed or component
recognizedbyauthoritieswhohave jurisdiction
forthe specificpurposeforwhichtheyareused.
IMPORTANT:
1. For on-off gas-fired systems, some authorities who
have jurisdiction prohibit the wiring of any limit or
operating contacts in series between the flame safe-
guard control and the main fuel valve(s).
2. TwoFlameDetectorscanbeconnectedinparallelwith
the exception of Infrared Flame Detector (817-1742).
CB780/CB784
INSTALLATION
Installation
3. This equipment generates, uses and can radiate radio
frequency energy and, if not installed and used in
accordance with the instructions, may cause interfer-
ence to radio communications. It has been tested and
found to comply with the limits for a Class B comput-
ingdeviceofPart15ofFCCruleswhicharedesigned
to provide reasonable protection against such inter-
ference when operated in a commercial environment.
Operation of this equipment in a residential area may
cause interference; in which case, the users at their
own expense may be required to take whatever mea-
sures are required to correct this interference.
4. This digital apparatus does not exceed the Class B
limits for radio noise for digital apparatus set out in
the Radio Interference Regulations of the Canadian
Department of Communications.
HUMIDITY
Install the CB780/CB784 where the relative humidity
never reaches the saturation point. The CB780/CB784 is
designed to operate in a maximum 85% RH continuous,
noncondensing, moisture environment. Condensing mois-
ture may cause a safety shutdown.
VIBRATION
Do not install the CB780/CB784 where it could be sub-
jected to vibration in excess of 0.5G continuous maximum
vibration.
WEATHER
TheCB780/CB784 isnotdesignedtobeweathertight.If
installed outdoors, the CB780/CB784 must be protected by
an approved weather-tight enclosure.
MOUNTING WIRING SUBBASE
NOTE: For installation dimensions, see Fig. 1.
1. Mountthe subbasein anyposition excepthorizontally
with the bifurcated contacts pointing down. The standard
vertical position is recommended. Any other position de-
creases the maximum ambient temperature rating.
2. The 833-2725 Wiring Subbase can be mounted di-
rectly in the control cabinet. Be sure to allow adequate clear-
ance for servicing, installation, access or removal of the
CB780/CB784, Expanded Annunciator, Keyboard Dis-
playModule,flameamplifier,flameamplifiersignalvoltage
probes, Run/Test Switch, electrical signal voltage probes
and electrical field connections.
3. Forsurfacemounting,use the backofthe subbase asa
template to mark the four screw locations. Drill the pilot
holes.
4. Securely mount the subbase using four no. 6 screws.

1-10 750-166
CB780/CB784
INSTALLATION
Fig. 6—Internal block diagram of the CB780/CB784 (see Figs.7,8,9, or 10 for detailed wiring instructions).
2
CONFIGURATION
JUMPERS
MICROCOMPUTER
RESET
PUSHBUTTON
RUN/TEST
SWITCH
STATUS LEDs
PLUG-IN PURGE
TIMER CARD
SAFETY RELAY
CIRCUIT
POWER SUPPLY
KEYBOARD
DISPLAY MODULE
HIGH FIRE
COMMON
MODULATE
LOW FIRE
HIGH FIRE SWITCH
PLUG-IN
FLAME
AMPLIFIER
RELAY
DRIVE
CIRCUIT
CONTROL
POWER
TEST
JACK
REMOTE
RESET
DDL
DDL
COMMUNICATIONS
INDICATES FEEDBACK SENSING
TO RELAY STATUS FEEDBACK
AND LINE VOLT INPUTS
FIELD WIRING
INTERNAL WIRING
IGNITION
PILOT
PILOT/V2
MAIN VALVE
1K
9K
RELAY
STATUS
FEEDBACK
AND LINE
VOLTAGE
INPUTS
LIMITS CONTROLLER LOCKOUT
INTERLOCK
PRE-IGNITION
INTERLOCK
1K1 2K1 5K1
8K1
8K2
9K1
9K2
120 Vac
FLAME SIGNAL
TEST
LOW FIRE SWITCH
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
RS485
123
L1
(HOT) L2
4
6
20
7
4K1
7K1
2K2
10
8
21
9
18
19
8K
7K
6K
5K
4K
3K
2K
F
G
22
1
BLOWER
6K1 5
ALARM
3K1 3
L2
12
13
15
14
M7420
1
2 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF THE BOILER CONTROL PANEL.

750-166 1-11
CB780/CB784
WIRING
1. a. For proper subbase wiring, refer to Fig. 7.
b. For proper remote wiring of the Keyboard Dis-
play Module, refer to Fig. 8, 9 or 10 or to the
Specifications for the Keyboard Display Module,
Communication Interface Base Unit or Control
Bus.
2. Disconnect the power supply from the main discon-
nect before beginning installation to prevent electrical
shock and equipment damage. More than one disconnect
may be involved.
3. All wiring must comply with all applicable electrical
codes, ordinances and regulations. Wiring, where required,
must comply with NEC, Class 1 (Line Voltage) wiring.
4. Recommended wire size and type:
a. All Line Voltage terminals use no. 14 or 16 cop-
per conductor (90°C or higher) 600 volt insula-
tion wire (wire size must be coordinated with fuse
protection). For high temperature installations,
use wire selected for a temperature rating above
the maximum operating temperature. All leadwires
should be moisture resistant.
b. Keyboard Display Module—For communica-
tionspurposes,useanunshielded22AWG 2-wire
twisted cable and one wire for ground if the
leadwire run and noise conditions permit; how-
ever, some installations may need up to five wires,
threeforcommunicationsandtwo forremotereset
(in either a single cable or separate cables for com-
munications or remote reset) or use Belden 8771
shielded cable or equivalent. The Keyboard Dis-
play Module, ControlBus (for remote mounting or
communications) or Communication Interface
ControlBusModulemustbe wiredinadaisy chain
configuration,(1(a)-1(a),2(b)-2(b),3(c)-3(c)).The
order of interconnection of all the devices listed
above is not important. Be aware that modules on
the closest and farthest end of the daisy chain
configuration string require a 120 ohm (1/4 watt
minimum) resistor termination across terminals
1 and 2 of the electrical connectors, for connec-
tions over 100 feet, see Fig. 8, 9 and 10.
c. Control Bus—For communications purposes,
use an unshielded 22 AWG 2-wire twisted cable
if the leadwire run and noise conditions permit;
however, some installations may need up to five
wires, three for communications and two for re-
mote reset (in either a single cable or separate
cables) or use a Belden 8771 shielded cable or
equivalent. The Keyboard Display Module, Con-
trolBus(for remotemountingorcommunications)
or Communication Interface ControlBus Module
must be wired in a daisy chain configuration,
(1(a)-1(a), 2(b)-2(b),3(c)-3(c)).Theorderofinter-
connection of all the devices listed above is not
important. Be aware that modules on the closest
and farthest end of the daisy chain configuration
string require a 120 ohm (1/4 watt minimum) resis-
tor termination across terminals 1 and 2 of electri-
cal connectors, for connections over 100 feet, see
Fig. 8, 9 and 10.
d. Remote Reset*—Use no. 22 AWG or greater
twisted pair wire, insulated for low voltage; see
Fig. 8, 9 and 10.
e. Communication Interface ControlBus Module—
For communications purposes, use an unshielded
22 AWG 2-wire twisted cable if the leadwire run
and noise conditions permit or use a Belden 8771
shielded cable or equivalent. The Keyboard
Display Module, Control Bus (for remote mount-
ing or communications) or Communication Inter-
face ControlBus Module must be wired in a daisy
chainconfiguration,(1(a)-1(a),2(b)-2(b),3(c)-3(c)).
The order of interconnection of all the devices
listed above is not important. Be aware that
modules on the closest and farthest end of the
daisy chain configuration string require a 120
ohm (1/4 watt minimum) resistor termination
acrossterminals1and2of the electrical connec-
tors, for connections over 100 feet, see Fig. 8, 9
and 10.
f. Use the recommended wire size for the 13 Vdc
full wave rectified transformer power input of
no. 18 AWG wire insulated for voltages and tem-
peratures encountered in the application. Sug-
gested wire typesinclude TTW(60C), THW(75C)
and THHN(90C).
5. Recommended grounding practices:
a. The earth ground provides for a connection be-
tween the subbase and the control panel of the equip-
ment. The earth ground wire must be capable of
conducting the current to blow the 20A fuse (or
breaker) in event of an internal short circuit. The
CB780/CB784 needs a low impedance ground
connection to the equipment frame which, in
turn, needs a low impedance connection to earth
ground. For a ground path to be low impedance
at RF frequencies, the connection must be made
with minimum length conductors that have a
maximumsurfacearea.Wide straps orbrackets
are preferred rather than leadwires. Be careful to
ensurethatmechanicallytightenedjointsalong
the ground path, such as pipe or conduit threads
or surfaces held together with fasteners, are free
of nonconductive coatings and are protected
against corrosion on mating surfaces.
b. Keyboard Display Module, Control Bus, or
Comm unication Interface ControlBus Module—
Wiring
*Note: Remote Reset must be mounted within sight
of the boiler control panel.

1-12 750-166
CB780/CB784
WIRING
The shield, if used, should be connected to the
signal ground terminal 3(c) provided as part of the
CB780/CB784 device ControlBus connection.
Connect the shield at both ends to earth ground.
c. CB780/CB784—Each CB780/CB784 will have
an earth ground terminal that must be grounded to
the metal control panel with wire as short as prac-
tical.Eachgroundwiremustbecapableofcarrying
a fault current equal to the rating of the protec-
tive fuse (20A). A number 14 copper conductor
is adequate, but wide straps or brackets are pre-
ferred rather than leadwires.
6. Recommended wire routing:
a. Flame detector leadwires:
1. Do not run high voltage ignition transformer
wiresinthesameconduitwiththeflamedetec-
tion wiring.
2. Do not route scanner wires in conduit with line
voltage circuits.
3. Enclose scanner wires without armor cable in
metal cable or conduit.
4. Follow directions in flame detector Instructions.
b. Control Bus:
1. Do not run high voltage ignition transformer
wires in the same conduit or close proximity
with the Control Bus wiring.
2. DonotrouteControlBuswiresinconduitwithline
voltage circuits.
c. Keyboard Display Module (VFD): Because the
VFD is powered from a low voltage, energy lim-
ited source, it can be mounted outside of a control
panel if it is protected from mechanical damage.
d. Remote Reset:
1. Do not run high voltage ignition transformer
wiresinthesame conduitwiththeRemote Reset
wiring.
2. Do not route Remote Reset wires in conduit
with line voltage circuits.
NOTE: A13 Vdcpowersupplymustbeusedanytimemore
than one Keyboard Display Module is used.
7. Maximum wire lengths:
a. CB780/CB784 leadwires—The maximum length
of leadwire is 300 feet to terminal inputs (Control,
Preignition Interlock, Running/Lockout Interlock,
High Fire Switch and Low Fire Switch).
b. FlameDetectorleadwires—Themaximumflame
sensor leadwire length is limited by the flame
signal strength.
c. Remote Reset leadwires—The maximum length
of wire is 1000 feet to a Remote Reset pushbutton.
d. Control Bus—The maximum Control Bus cable
length depends on the number of system modules
connected,thenoise conditionsandthecableused.
The maximum length of all interconnecting wire
is 1000 feet.
8. Make sure loads do not exceed the terminal ratings.
Refer to the label on the CB780/CB784 or to the ratings in
Specifications; see Table 1.
9. Check the power supply circuit. The voltage and fre-
quencytolerancemustmatchthoseoftheCB780/CB784. A
separate power supply circuit may be required for the
CB780/CB784. Add the required disconnect means and
overload protection.
10. Check all wiring circuits and complete the Static
Checkout, see Table 8, before installing the CB780/CB784
on the subbase.
11. Install all electrical connectors.
12. Restore power to the panel.

750-166 1-13
CB780/CB784
WIRING
FIG. 7—WIRING CB780/CB784
M7408
G
L2
3
4
5
6
7
8
9
10
F
(L1)
13
14
15
16
17
18
19
20
21
22
12
LOCKOUT INTERLOCKS
(INC. AIR FLOW SWITCH)
MASTER
SWITCH
LOW FIRE
START SWITCH
5 SECOND IGNITION
(EARLY SPARK)t
(TERMINATION)
MAIN FUEL
VALVE(S)
BURNER
CONTROLLER/LIMITS
BURNER MOTOR
(BLOWER)
HIGH FIRE
COMMON
LOW FIRE
MODULATE
120V ALARM
10 SEC. INTERRUPTED
PILOT/IGNITION
PREIGNITION
INTERLOCK
SERIES 90
FIRING RATE
MOTOR SERIES 90
CONTROLLER
817-1742
INFRARED
(LEAD SULFIDE)
FLAME DETECTOR
817-1743
ULTRAVIOLET
FLAME DETECTOR
817-1121
ULTRAVIOLET
FLAME DETECTOR
120V, 60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
DO NOT WIRE TO ANY UNUSED TERMINALS.
FOR DIRECT SPARK IGNITION (OIL
OR GAS)
IGNITION
TRANSFORMER
2ND STAGE
FUEL VALVE
(OPTIONAL)
R
W
B
R
W
B
L1
(HOT)
L2 1
OR
OR
BLUE
BLUE
WHITE
YELLOW
L2
WHITE
WHITE
BLACK
BLACK L1
L2
8
9
10
L2
833-2725
2
15 SEC.
INTERRUPTED
PILOT VALVE
2
1
HIGH FIRE
PURGE SWITCH
(EARLY SPARK
TERMINATION)

1-14 750-166
CB780/CB784
WIRING
L1
(HOT)
L2
1
1
120 OHM
RESISTOR
1
120 OHM
RESISTOR
A B
A B
C (GND)
+13 VDC
RESET
C (GND)
+13 VDC
RESET
123 45
123 45
MOMENTARY
PUSH BUTTON
SWITCH
833-2727 KEYBOARD DISPLAY MODULE
(MOUNTED ON CB 780/CB 784)
13 VDC
POWER SUPPLY
833-2727 REMOTE KEYBOARD DISPLAY MODULE
THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO 120
OHM TERMINATING RESISTORS ARE REQUIRED FOR
CONNECTIONS OVER 100 FEET. CABLE SHIELD MUST BE
TERMINATED TO EARTH GROUND AT BOTH ENDS. IF SHIELDED
CABLE IS NOT USED, TWISTED PAIR WIRE MUST BE USED.
M7409
Fig. 8—Wiring the Keyboard Display Module with
Communication Interface ControlBus Module. Fig. 9—Wiring multiple Keyboard Display Modules.
Fig. 10—Wiring the Control Bus with remote Keyboard Display Module.
2
2 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF
THE BOILER CONTROL PANEL.
2 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF
THE BOILER CONTROL PANEL.
1
1
120 OHM
RESISTOR
1
120 OHM
RESISTOR
A B
A B CC (GND)
+13 VDC
RESET
123 45
123
MOMENTARY
PUSH BUTTON
SWITCH
833-2727 KEYBOARD DISPLAY MODULE
(MOUNTED ON CB 780/CB 784)
833-2734
COMMUNICATIONS
INTERFACE
CONTROLBUS
MODULE
THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO 120
OHM TERMINATING RESISTORS ARE REQUIRED FOR
CONNECTIONS OVER 100 FEET (30 METERS). CABLE SHIELD
MUST BE TERMINATED TO EARTH GROUND AT BOTH ENDS.
IF SHIELDED CABLE IS NOT USED, TWISTED PAIR
WIRE MUST BE USED. M7406
3
2
1
1
2
2
120 OHM
RESISTOR
1
120 OHM
RESISTOR
A B
A B
C (GND)
+13 VDC
RESET
C (GND)
+13 VDC
RESET
123 45
123 45
MOMENTARY
PUSH BUTTON
SWITCH
833-2729 DATA CONTROLBUS MODULE™
(MOUNTED ON CB 780/CB 784)
833-2727 REMOTE KEYBOARD DISPLAY MODULE
THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO 120
OHM TERMINATING RESISTORS ARE REQUIRED FOR
CONNECTIONS OVER 100 FEET. CABLE SHIELD MUST BE
TERMINATED TO EARTH GROUND AT BOTH ENDS. IF SHIELDED
CABLE IS NOT USED, TWISTED PAIR WIRE MUST BE USED.
WHEN CONNECTING THE KEYBOARD DISPLAY MODULE DATA
CONTROLBUS MODULE™, OR REMOTE RESET MODULE
EXTERNAL FROM THE CONTROL CABINET, APPROPRIATE
MEASURES MUST BE TAKEN TO MEET EN60730 SAFETY
LOW VOLTAGE REQURIEMENTS (SEE APPROVALS).
M7407
833-2729 CONTROL BOX (MOUNTED ON CB780/CB784)
CONTROL BUS, OR REMOTE RESET MODULE
3 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF
THE BOILER CONTROL PANEL.

750-166 1-15
CB780/CB784
ASSEMBLY
IMPORTANT:TheCB780 willnotfunctionproperlywith-
outoneofthe following mountedcorrectly:Keyboard
Display Module, or Control Bus .
MOUNTING KEYBOARD DISPLAY MODULE
(VFD)
1. Align the two interlocking ears of the Keyboard Dis-
playModulewith thetwomating slotsontheCB780/CB784;
see Fig. 13.
2. Insertthetwointerlockingearsintothetwomatingslots
and with a hinge action push on the lower corners of the
Keyboard Display Module to secure it to the CB780/CB784.
3. VerifytheKeyboardDisplayModuleisfirmlyinplace.
MOUNTING CONTROL BUS
1. Align the two interlocking ears with the two mating
slots on the CB780/CB784; see Fig. 14.
2. Insert the two interlocking ears into the two mating
slots and push on the lower corners of the Control Bus to
secure it to the CB780/CB784.
3. Be sure the Control Bus is firmly in place.
Assembly
MOUNTING CB780/CB784
NOTE: For installation dimensions, see Fig. 1.
RELAY MODULE MOUNTING
1. Mount the CB780/CB784 vertically, see Fig. 11, or
mount horizontally with the knife blade terminals pointing
downward. The CB780/CB784 must be in an electrical
enclosure.
2. Select the location in the electrical enclosure. Be sure
to allow adequate clearance for servicing, installation and
removal of the CB780/CB784, Keyboard Display Module,
flameamplifier,flameamplifiersignalvoltageprobes, elec-
trical signal voltage probes, and electrical connections.
a. Allow an additionaltwoinchesbelowtheCB780/CB784
for the flame amplifier mounting.
d. Allow an optional three-inch minimum to both sides
of the CB780/CB784 for electrical signal voltage
probes.
3. Makesurenosubbasewiring is projecting beyond the
terminal blocks. Tuck wiring in against the back of the sub-
base so it does not interfere with the knife blade terminals or
bifurcated contacts.
IMPORTANT:TheCB780/CB784mustbeinstalledwitha
plug-in motion rather than a hinge action.
4. MounttheCB780/CB784byaligningthefourLshaped
corner guides and knife blade terminals with the bifurcated
contactsonthewiringsubbaseandtighteningthetwoscrews
securely without deforming the plastic.
INSTALLING THE PURGE CARD
1. Remove the Keyboard Display Module or Control
Bus, see Fig. 13 or 14.
2. RemovethecurrentPurgeCardfromtheCB780/CB784
by pulling the plastic support cover upward .
3. Makesure thatthePurgeCard selectedhasthedesired
timing.
4. Insert Purge Card intothe opening ofthe CB780/CB784
compartment, see Fig. 12.
5. Reinstall the Keyboard Display Module or Control
Bus onto the CB780/CB784 and restore power to the
device.
6. Run the burner system through at least one complete
cycle to verify the system is operating as desired.
Fig. 11—Electrical panel installation.

1-16 750-166
CB780/CB784
ASSEMBLY
Fig. 12—Purge Card installation.
Fig. 13—Keyboard Display Module mounting.
Fig. 14—Control Bus mounting.
REMOTE MOUNTING OF KEYBOARD DISPLAY
MODULE (VFD)
1. TheKeyboardDisplayModule(VFD)canbemounted
eitheronthe face ofapanel door oronother remotelocations;
see Fig. 15.
2. WhenmountingtheKeyboardDisplay Moduleonthe
face of a door panel, closely follow these instructions:
a. Select the location on the door panel for flush mount-
ing.Payattentiontotheinsertiondimensionofthetwo
Keyboard Display Module screws, two interlocking
ears and the two plug-in connectors to allow for
sufficient clearance, 1/4 inch minimum inward from
the surface of the door panel.
b. Use the Keyboard Display Module as a template; see
Fig. 28. Mark the two screw locations, two interlock-
ing ear locations and two plug-in connector locations.
Drill the pilot holes for the mounting screws. Provide
for two holes on the door panel for the interlocking
ears and plug-in connector holes.
c. Mount the Keyboard Display Module securing the
two no. 4 screws.
INSTALLING PLUG-IN FLAME SIGNAL
AMPLIFIER
1. Disconnect power supply before beginning installation
topreventelectrical shockandequipment damage.Morethan
one disconnect may be involved.
2. Align the amplifier circuit board edge connector with
the keyed receptacle on the CB780/CB784. Verify the am-
plifier nameplate faces away from the Relay Module, see
Fig. 16.
3. Push in the amplifier until the circuit board is fully
inserted into the receptacle and then push the amplifier
toward the CB780/CB784 retaining clasp.
4. Verify the amplifier is firmly in place.
5. Perform all required checkout tests.
INSTALLING THE FLAME DETECTOR
NOTE: Table 2 lists the flame detection systems available
for use with the CB780/CB784. Make sure the correct
combination of amplifier and flame detector(s) is used.
Properflamedetectorinstallationisthebasisofasafeand
reliable flame safeguard installation. Refer to the instruc-
tions packed with the flame detector and the equipment
manufacturer instructions; see Fig. 17.
Keeptheflamesignal leadwires asshortaspossible from
the flame detector to the wiring subbase. Capacitance in-
creases with leadwire length, reducing the signal strength.
The maximum permissible leadwire length depends on the
type of flame detector, leadwire and conduit. The ultimate
limiting factor in the flame detector leadwire is the flame
signal; see Table 9.