Cleaver-Brooks CB780, CB784 Operation And Maintenance Manual

$25.00

Cleaver-Brooks

CB780/CB784

Operation and Maintenance Manual

750-166

DIVISION OF AQUA-CHEM, INC.

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

© Aqua-Chem, Inc., 1995

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.

CONTENTS

Section 1 – Installation and Operating Instructions
Section 2 – System Annunciation Diagnostics and Troubleshooting

Section 1 - CB780/CB784

Installation and Operating Instructions

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. Sub­base, Amplifier, and Purge Card are r e quired to complete the
system. Options include Personal Computer Interface, Control
Bus, Remote Display Mounting, First-Out Expanded Annun­ciator 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 auto­matic burner sequencing, flame supervision, system status
indication, system or self-diagnostics and troubleshooting

.

■ Safety features:

—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-out annunciation and system diagnostics provided by

a 2 row by 20 column Vacuum Fluorescent Display (VFD)
located on the Keyboard Display Module.

■ First-out expanded annunciation with 26 Light Emitting

Diodes (LEDs) for limits and interlocks (optional).

■ Five sequence information Light Emitting Diodes (LEDs).

■ Five function Run/Test Switch.

■ Interchangeable plug-in flame amplifiers.

■ Local or remote annunciation of operation and fault

information.

■ Nonvolatile memory for retaining history files and 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.

—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

750-166 1-1

CB780/CB784
SPECIFICATIONS

Specif ications

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.

TABLE 1—TERMINAL RATINGS.

Terminal No. Description Ratings

G Flame Sensor Ground

Earth G Earth Ground

1

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.
9 Main Fuel Valve 120 Vac, 2A pilot duty.

10 Ignition 120 Vac, 4.5A Ignition.

4

3

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.

1

The CB780/CB784 must have an earth ground providing a connection between the subbase and the control panel or the equipment.
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 by minimum
length conductors having maximum surface areas. Wide straps or brackets are preferred rather than leadwires. Be careful to ensure
that mechanically tightened joints along the ground path, such as pipe or conduit threads or surfaces held together with fasteners, are
free of nonconductive coatings and are protected against mating surface corrosion.

2

2000 VA maximum connected load to CB780/CB784 Assembly.

3

Can also be 120 Vac, 1A pilot duty.

4

Can also be 65 VA pilot duty with motorized valve, 1150 VA inrush, 460 VA open, 250 VA hold.

5

Operating frequency chosen by CB780/CB784 selection.

1-2 750-166

CB780/CB784

SPECIFICATIONS

ENVIRONMENTAL RATINGS:

Ambient Temperature:

Operating: -40°F to 140°F.

WEIGHT:

CB780/CB784: 1 pound 10 ounces, unpacked.
Keyboard Display Module: 4 ounces, unpacked.

Storage: -40°F to 150°F.
Humidity: 85% RH continuous, noncondensing.
Vibration: 0.5G environment.

DIMENSIONS: Refer to Figs. 1 and -2.

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).

Plug-In Flame Amplifiers Applicable Flame Detectors

Flame

Failure

Part

Type Color Self-Checking

Number

Infrared Red No 833-2722 3 sec. Gas, oil,

Dynamic AMPLI-

Dynamic Auto-Check

CHECK™

833-2723

Response

Time Fuel Type

coal

c

Gas, oil,
coal

Infrared
(Lead Sulfide)

Infrared
(Lead Sulfide)

Part

Number

817-1742

817-1742

Ultraviolet Purple No 833-2724 Gas, oil Ultraviolet 817-1743
Ultraviolet

Self-Check

Green Dynamic Self-

Check

833-2741

b

Gas, oil,
coal

Ultraviolet
(Purple

817-1121

Peeper)

a

The 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.

b

Circuitry 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.

c

Circuitry tests the flame signal amplifier 12 times a minute during burner operation and shuts down the burner if the amplifier fails.

a

Firing

Rate

2

Energy

Saving

No FM/IRI

Approval

Code

Modulating

TABLE 3—SEQUENCE TIMING FOR NORMAL OPERATION.

Flame

Establishing

Period

Device Initiate Standby Purge Pilot Main Run

CB 780/
CB 784

* STANDBY and RUN can be an infinite time period.

** PURGE will be determined by which purge card is selected.

1

The MFEP will be determined by which terminal is used, see Figs. 7 and 18.

2

The operating sequence of the CB780 and CB784 Relay Modules are identical. The only difference between the Relay

10 sec * ** 4 or

10 sec

10 or
15 sec

* 15 sec Preignition,

1

Post

Purge Interlock

Timing Circuits Circuit Prepurge Bodies

Lockout,
High and
Low Fire

4-wire
modulating

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.
Federal Communications Commission, Part 15, Class B—

Emissions.

750-166 1-3

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.

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.

NOTE: The CB780 and CB784 are identical except for the

Keyboard Display Module which is standard with the
CB780 and optional with the CB784.

Fig. 1—Mounting dimensions of CB780/CB784 Relay Module and 833-2725 Subbase, in inches (mm)

BURNER CONTROL

SCROLL MODE

SAVE

5

(127)

POWER
PILOT
FLAME
MAIN
ALARM

RESET

5 (127)

1

REMOVE ONLY FOR TERMINAL TEST ACCESS.

1

5-1/4 (133)

M7399

1-4 750-166

CB780/CB784

,

,

SPECIFICATIONS

Fig. 2—Mounting dimensions of Keyboard
Display Module, in inches (mm).

BURNER CONTROL

2-3/4
(69)

15/
32
(12)

1-15/16
(49)

29/32
(23)

SCROLL MODE

19/32
(15)

5/32 (4)

4-27/32 (123)

1-1/4
(32)

7/16 (11)

2-5/16 (58)

3-7/8 (99)

SAVE

4-3/32 (104)

1-1/32
(26)

13/
32
(11)

5/32
(4)

1/2
(13)

5/16
(8)

2-1/32
(52)

5/15
(8)

29/32
(23)

M7405

Fig. 4—Ultraviolet detector.

4 (102)

3-1/2 (89)

COLLAR WITH 1/2-14 NPSM
INTERNAL THREADS

817-1743

Fig. 5—Infrared detector.

2-3/4

(70)

2 LEADS IN A
48 INCH [1.2 METER]
FLEXIBLE CONDUIT

BUSHING WITH
MAGNIFYING LENS

COLLAR, 3/4-14 NPSM
INTERNAL THREADS

817-1742

1-1/4

(32)

APERTURE

6 FOOT (1.83 METER)
LEADWIRES (2)

1-1/16

(27)

HEAT BLOCKCELL MOUNT

1-5/8 (41)

1-1/16 (27)

1-1/4

3/4-14
NPSM

3/4-14 NPSM
INTERNAL
THREADS

M7419

(32)

M1982A

833-2727

(Standard with CB780, optional with CB784)

Fig. 3—Ultraviolet Self-Check detector.

3-3/4

(95)

7-7/32

(183)

1/2–14 NPSM

LEADWIRES

MOUNTING FLANGE

817-1121

5-1/8 (130)

3-7/16

(87)

FACEPLATE

3/4–14 NPT

5-1/4 (133)

M1962A

750-166 1-5

CB780/CB784
PRINCIPAL TECHNICAL FEATURES

Principal T echnical Features

The CB780/CB784 provides all customary flame safe­guard functions while providing significant advancements in
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-

lock String (including the airflow switch) 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. Flame signal detected after first ten seconds during

PREPURGE.

c. High Fire Switch fails to close within four minutes,

fifteen seconds after firing rate motor is commanded
to drive to high fire position at start of PREPURGE.

d. Low Fire Switch fails to close within four minutes,

fifteen seconds after firing rate motor is commanded

to drive to low fire position at end of PREPURGE.
e. Lockout Interlock does not close within 10 seconds.
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/pilot valve/intermittent pilot valve terminal

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.

1-6 750-166

CB780/CB784

SAFETY PROVISIONS

Safety Pro visions

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, the CB780/CB784 will lockout on safety shut­down. The CB780/CB784 must react to input changes but
avoid the occurrence of nuisance shutdown events. Signal
conditioning is applied to line voltage inputs to verify proper
operation in the presence of normal electrical line noise such
as transient high voltage spikes or short periods of line
dropout. Signal conditioning is tolerant of synchronous noise
(line noise events that occur at the same time during each line
cycle).

DYNAMIC AUTO-CHECK

Dynamic Auto-Check circuitry tests the flame signal
amplifier during burner operation and shuts down the CB780/
CB784 if the flame amplifier fails.

DYNAMIC FLAME AMPLIFIER AND SHUTTER
CHECK

Self-checking circuitry tests all electronic components in
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,
terminals 8, 9, 10 and 21, can be de-energized, as required, by
the Dynamic Self-Check logic.

DYNAMIC SELF-CHECK SAFETY CIRCUIT

The microcomputer tests itself and related hardware
while at the same time the safety relay system tests the micro­computer 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

The conventional safe-start check, which prevents burner
start-up if flame is indicated at start-up, is expanded to
include a flame signal check during STANDBY, a preigni­tion 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 Posi­tion Interlock Switch at the moment the firing rate motor is
commanded to the high fire position. If the switch is by­passed, 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 annunci­ate 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
switch is bypassed, welded or otherwise prematurely closed,
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
after the Low Fire Switch closes. The test also is used to prove
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
and annunciate an alarm if the switch fails to close within the
hold time period.

750-166 1-7

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 am­plifier) is monitored during STANDBY. If a flame simulat­ing 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 shut­down will occur and be annunciated. A shutter-check ampli­fier 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 shut­down occurs. An Auto-Check Amplifier is energized con­tinually through STANDBY and PREPURGE to detect any
possibility of a runaway detector or a flame. If either situa­tion happens, a safety shutdown occurs. A standard amplifier
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
operation is checked. Also, all safety critical loads, terminals
8, 9, 10 and 21 are checked to verify the terminals are not
powered. If the Dynamic Safety Relay operation is faulty, or
if any of the safety critical loads are powered, safety shut­down 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 (five seconds ignition and pilot and five seconds
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, PILOT IGN, MAIN IGN, and POSTPURGE.
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 shut­down or identifies the cause of a failure to start or continue
the burner control sequence with an English text and num­bered code via the Keyboard Display Module. It monitors all
field input circuits, including the Flame Signal Amplifier
and Firing Rate Position Switches. The system distinguishes
118 modes of failure and detects and annunciates difficult­to-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 re­ported by the Keyboard Display Module. See the Diagnos­tics and Troubleshooting section of the CB780/CB784 Op­eration and Maintenance Manual, Manual Number 750-166.

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
entering PREPURGE, if the Lockout Interlock opens during
the first ten seconds, the purge timer will be reset. This
provides a continuous PURGE to occur without interruption
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 configur­able 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 (including airflow switch) is closed during STANDBY.

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
interlock does not close within 30 seconds during STANDBY.
If the Preignition Interlock opens during PREPURGE, it
will lockout. If the Preignition Interlock is open after five sec­onds into POSTPURGE, the CB780/CB784 will lockout.
The Preignition Interlock is ignored during the ignition trials
state and during RUN.

1-8 750-166

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
marked on the product to make sure the product is suitable
for the application.

3. Installer must be a trained, experienced, flame safe­guard service technician.

4. After installation is complete, check out the product
operation as provided in these instructions.

CA UTION

1. Disconnect the power supply before beginning
installation to prevent electrical shock, equip-
ment and control damage. More than one power
supply disconnect may be involved.

2. Wiring connections for the CB780/CB784 are
unique; therefore, refer to Figs. 6, 7, 8 o r 9 or
the correct Specifications for proper subbase
wiring.

3. Wiring must comply with all applicable codes,
ordinances and regulations.

4. Wiring, where required, must comply with NEC
Class 1 (Line Voltage) wiring.

5. Loads connected to the CB780/CB784 must not
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, pilot valve, and main fuel valve(s).

7. All external timers must be listed or component
recognized by authorities who have jurisdiction
for the specific purpose for which they are used.

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 safe­guard control and the main fuel valve(s).

2. Two Flame Detectors can be connected in parallel with
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 interfer­ence to radio communications. It has been tested and
found to comply with the limits for a Class B comput­ing device of Part 15 of FCC rules which are designed
to provide reasonable protection against such inter­ference 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 mea­sures 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 mois­ture may cause a safety shutdown.

VIBRATION

Do not install the CB780/CB784 where it could be sub­jected to vibration in excess of 0.5G continuous maximum
vibration.

WEATHER

The CB780/CB784 is not designed to be weather tight. 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. Mount the subbase in any position except horizontally
with the bifurcated contacts pointing down. The standard
vertical position is recommended. Any other position de­creases the maximum ambient temperature rating.

2. The 833-2725 Wiring Subbase can be mounted di­rectly in the control cabinet. Be sure to allow adequate clear­ance for servicing, installation, access or removal of the
CB780/CB784, Expanded Annunciator, Keyboard Dis­play Module, flame amplifier, flame amplifier signal voltage
probes, Run/Test Switch, electrical signal voltage probes
and electrical field connections.

3. For surface mounting, use the back of the subbase as a
template to mark the four screw locations. Drill the pilot
holes.

4. Securely mount the subbase using four no. 6 screws.

750-166 1-9

CB780/CB784
INSTALLATION

Fig. 6—Internal block diagram of the CB780/CB784 (see Figs.7,8,9, or 10 for detailed wiring instructions).

4

RESET
PUSHBUTTON

STATUS LEDs

RUN/TEST
SWITCH

CONFIGURATION
JUMPERS

MICROCOMPUTER

SAFETY RELAY
CIRCUIT

RELAY
DRIVE
CIRCUIT

L1
(HOT) L2

1

120 Vac

2K
3K
4K
5K

6K
7K
8K
9K

1K

POWER SUPPLY

PLUG-IN PURGE
TIMER CARD

FLAME SIGNAL

PLUG-IN
FLAME
AMPLIFIER

TEST

L2

TEST
JACK

F

G

22

RELAY
STATUS
FEEDBACK
AND LINE
VOLTAGE
INPUTS

CONTROL
POWER

20

PRE-IGNITION
INTERLOCK

LIMITS CONTROLLER

6K1

3K1

KEYBOARD

DDL

DISPLAY MODULE

RS485

DDL
COMMUNICATIONS

PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

1

1

2

LOCKOUT
INTERLOCK

6

LOW FIRE SWITCH

18

HIGH FIRE SWITCH

19

REMOTE

3

RESET

1K1 2K1 5K1

7

4K1

7K1

2K2

HIGH FIRE

8K1

COMMON

8K2

MODULATE

9K2

LOW FIRE

2

9K1

12

13

15

14

2 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF THE BOILER CONTROL PANEL.

10

8

21

9

5

3

INDICATES FEEDBACK SENSING
TO RELAY STATUS FEEDBACK
AND LINE VOLT INPUTS

FIELD WIRING
INTERNAL WIRING

IGNITION

PILOT

PILOT/V2

MAIN VALVE

BLOWER

ALARM

M7420

1-10 750-166

CB780/CB784

Wiring

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 insula­tion 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-

tions purposes, use an unshielded 22 AWG 2-wire
twisted cable and one wire for ground if the
leadwire run and noise conditions permit; how­ever, some installations may need up to five wires,
three for communications and two for remote reset
(in either a single cable or separate cables for com­munications or remote reset) or use Belden 8771
shielded cable or equivalent. The Keyboard Dis­play Module, Control Bus (for remote mounting or
communications) 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)). 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 connec­tions 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 re­mote reset (in either a single cable or separate
cables) or use a Belden 8771 shielded cable or
equivalent. The Keyboard Display Module, Con­trol Bus (for remote mounting or communications)
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)). 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 electri­cal 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 mount­ing or communications) 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)).
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 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 tem­peratures encountered in the application. Sug­gested wire types include 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 equip­ment. 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
maximum surface area. Wide straps or brackets
are preferred rather than leadwires. Be careful to
ensure that mechanically tightened joints along
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,

Comm

unication Interface ControlBus Module—

Control Bus, or

750-166 1-11

*Note: Remote Reset must be mounted within sight
of the boiler control panel.

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 prac­tical. Each ground wire must be capable of carrying
a fault current equal to the rating of the protec­tive fuse (20A). A number 14 copper conductor
is adequate, but wide straps or brackets are pre­ferred rather than leadwires.

6. Recommended wire routing:
a. Flame detector leadwires:

1. Do not run high voltage ignition transformer
wires in the same conduit with the flame detec­tion 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. Do not route Control Bus wires in conduit with line
voltage circuits.

c. Keyboard Display Module (VFD): Because the

VFD is powered from a low voltage, energy lim­ited 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
wires in the same conduit with the Remote Reset
wiring.

2. Do not route Remote Reset wires in conduit
with line voltage circuits.

NOTE: A 13 Vdc power supply must be used any time more

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. Flame Detector leadwires—The maximum flame

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, the noise conditions and the cable used.
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-

quency tolerance must match those of the CB780/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.

1-12 750-166

FIG. 7—WIRING CB780/CB784

833-2725

G

12

HIGH FIRE

SERIES 90
FIRING RATE
MOTOR

B

SERIES 90
CONTROLLER

B

CB780/CB784

WIRING

13

14

15

16

17

18

19

20

21

22

COMMON

LOW FIRE

MODULATE

LOW FIRE
START SWITCH

HIGH FIRE
PURGE SWITCH

PREIGNITION
INTERLOCK

15 SEC.
INTERRUPTED
PILOT VALVE

MASTER
SWITCH

R

W

L1
(HOT)

L2

R

W

1

120V ALARM

BURNER MOTOR
(BLOWER)

BURNER
CONTROLLER/LIMITS

LOCKOUT INTERLOCKS
(INC. AIR FLOW SWITCH)

10 SEC. INTERRUPTED
PILOT/IGNITION

MAIN FUEL
VALVE(S)

5 SECOND IGNITION
(EARLY SPARK)t

(EARLY SPARK

(TERMINATION)

TERMINATION)

817-1742
INFRARED
(LEAD SULFIDE)
FLAME DETECTOR

L2

10

3

(L1)

4

5

6

7

8

9

F

OR

WHITE

817-1743
ULTRAVIOLET
FLAME DETECTOR

OR

YELLOW

1
2

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.

BLUE

BLUE

WHITE
WHITE
BLACK
BLACK

FOR DIRECT SPARK IGNITION (OIL
OR GAS)

IGNITION

10

TRANSFORMER

8

2ND STAGE

9

FUEL VALVE

L2
L1

L2

(OPTIONAL)

2

L2

M7408

750-166 1-13

CB780/CB784

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

1

23

4

5

1

23

4

5

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

WIRING

Fig. 8—Wiring the Keyboard Display Module with
Communication Interface ControlBus Module.

833-2727 KEYBOARD DISPLAY MODULE
(MOUNTED ON CB 780/CB 784)

MOMENTARY
PUSH BUTTON

A

1

120 OHM
RESISTOR

120 OHM
RESISTOR

1

A

THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO 120

1

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.

2 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF
THE BOILER CONTROL PANEL.

B

C (GND)

23

1

1

23

B

C

RESET

+13 VDC

4

5

833-2734
COMMUNICATIONS
INTERFACE
CONTROLBUS
MODULE

SWITCH

2

M7406

Fig. 9—Wiring multiple Keyboard Display Modules.

2

2 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF
THE BOILER CONTROL PANEL.

Fig. 10—Wiring the Control Bus with remote Keyboard Display Module.

833-2729 DATA CONTROLBUS MODULE™
(MOUNTED ON CB 780/CB 784)

833-2729 CONTROL BOX (MOUNTED ON CB780/CB784)

1-14 750-166

MOMENTARY
PUSH BUTTON

A

1

120 OHM
RESISTOR

120 OHM
RESISTOR

1

A

833-2727 REMOTE KEYBOARD DISPLAY MODULE

THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO 120

1

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

2

CONTROL BUS, OR REMOTE RESET MODULE

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).

3 REMOTE RESET MUST BE MOUNTED WITHIN SIGHT OF
THE BOILER CONTROL PANEL.

B

C (GND)

23

2

1

1

23

B

C (GND)

+13 VDC

4

4

+13 VDC

RESET

5

5

RESET

SWITCH

M7407

3

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,
flame amplifier, flame amplifier signal voltage probes, elec­trical signal voltage probes, and electrical connections.

a. Allow an additional two inches below the CB780/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. Make sure no subbase wiring is projecting beyond the
terminal blocks. Tuck wiring in against the back of the sub­base so it does not interfere with the knife blade terminals or
bifurcated contacts.

CB780/CB784

ASSEMBLY

Assembly

Fig. 11—Electrical panel installation.

IMPORTANT: The CB780/CB784 must be installed with a

plug-in motion rather than a hinge action.

4. Mount the CB780/CB784 by aligning the four L shaped
corner guides and knife blade terminals with the bifurcated
contacts on the wiring subbase and tightening the two screws
securely without deforming the plastic.

INSTALLING THE PURGE CARD

1. Remove the Keyboard Display Module or Control
Bus, see Fig. 13 or 14.

2. Remove the current Purge Card from the CB780/CB784
by pulling the plastic support cover upward .

3. Make sure that the Purge Card selected has the desired
timing.

4. Insert Purge Card into the opening of the 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.

IMPORTANT: The CB780 will not function properly with-

out one of the following mounted correctly: Keyboard
Display Module, or Control Bus .

MOUNTING KEYBOARD DISPLAY MODULE
(VFD)

1. Align the two interlocking ears of the Keyboard Dis­play Module with the two mating slots on the CB780/CB784;
see Fig. 13.

2. Insert the two interlocking ears into the two mating slots
and with a hinge action push on the lower corners of the
Keyboard Display Module to secure it to the CB780/CB784.

3. Verify the Keyboard Display Module is firmly in place.

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.

750-166 1-15