Lincoln 1633-000-EA, 1634-000-EA User Manual

SERVICE MANUAL

(INTERNATIONAL)

IMPINGER CONVEYOR OVENS

MODEL 1633-000-EA, 1634-000-EA

WITH PUSH BUTTON CONTROLS

Lincoln Foodservice Products, LLC

1111 North Hadley Road

Fort Wayne, Indiana 46804

United States of America

Phone : [phone]

U.S. Fax: [phone] • Int’l Fax: [phone]

Technical Service Hot Line

[phone]

www.lincolnfp.com

1600ExpDigAdv REV: 1/8/07

SEQUENCE OF OPERATIONS

SERIAL NUMBERS L28563 AND ABOVE

(WITH PUSH BUTTON CONTROL)

MODEL 1633-000-EA 230 VAC 50HZ NATURAL GAS
MODEL 1634-000-EA 230 VAC 50HZ LP GAS

POWER SUPPLY Electrical power to be supplied to the oven by a three conductor service.

Brown conductor is hot
Blue conductor is neutral.

Green conductor is ground.
CONTROL BOX
AUTO COOL DOWN

When the temperature in either one of the control boxes reaches 120°F ±3° (49°C ±

1.7°), the cooling fan thermostats will switch power to the cooling fans. The thermostats

will interrupt power to the cooling fans when the temperature falls to 100°F ± 3° (37°C ±

1.7°)

MAIN FAN CIRCUIT Line voltage is permanently supplied to a normally open contact of the oven power switch.

Line voltage is permanently supplied to the two normally open cooling fan thermostats, a

normally open contact of the oven power relay. Closing the oven power switch supplies line

voltage, through both normally closed control box hi-limit thermostats, to the oven power

relay. Its contacts now close supplying line voltage to the two main fan motors and the two

burner circuits. Closing the oven power switch also supplies line voltage to the control box

cooling fans, the control transformer, and the conveyor motor.
BURNER CIRCUIT NOTE: This oven utilizes two complete burner systems. The sequence of operations is the

same for each system.

Closing the main fan switch supplies line voltage, through the oven power relay, through a

three Amp.fuse, through the gas pressure switch (gas pressure switch removed at

S/N L31479), through the main fan air pressure switch, through the oven cavity hi-limit

thermostat, to the ignition control. The combustion motor is energized. The normally open

combustion air switch closes upon sensing air pressure. After a pre-pu rge period of

between 30 and 60 seconds, the ignition transformer and the main gas valve are

energized. Ignition should now occur.
TEMPERATURE
CONTROL

Closing the oven power switch supplies line voltage, through the 10 amp. fuse, through the

oven power relay, to the primary of the control transformer. 24VAC is supplied to the oven

control. The oven control is set to desired temperature. The thermocouple will provide

varying millivolts to the oven control. The oven control supplies line voltage to the

temperature regulation valve at intermittent intervals to maintain desired temperature. The

display on the oven control will indicate when the temperature regulation valve is

energized.

NOTE: The display also indicates oven temperature.
CONVEYOR DRIVE Closing the oven power switch supplies line voltage, through the 10 Amp fuse, through the

oven power relay to the conveyor motor and to the primary of the control transformer.

Secondary voltage, 24VAC, is supplied to the oven control. Setting the oven control to the

desired time outputs voltage, through a reversing switch, to the conveyor motor

NOTE: The conveyor system uses a magnet and hall effect sensor to prove operation of

the conveyor motor. If the conveyor motor is not running, “BELT JAM” is indicated on the

display.

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SCHEMATIC

MODELS 1633-000-EA AND 1634-000-EA

SERIAL NUMBER L28563 TO L31478

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SCHEMATIC

MODELS 1633-00-EA AND 1634-000-EA

SERIAL NUMBER L31479 AND ABOVE

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TROUBLESHOOTING GUIDE

MODEL 1633-000 EA NATURAL GAS 230 VAC 50 HZ 1 PHASE
MODEL 1634-000-EA LP GAS 230 VAC 50 HZ 1 PHASE

NOTE: When checking components on left side of unit, be sure to check for pro per connections in power
connector, (marked P. C. on schematic diagram) located inside motor cover.

SYMPTOM POSSIBLE CAUSE EVALUATION
Oven fan will not
run

No control box
cooling

No automatic
control box cooling

Oven will not heat

NOTE: These ovens utilize 2 complete Burner/Temperature control systems. Each system will Follow the same
troubleshooting sequence.
Oven power relay Check for line voltage to the relay coil. If no voltage is

L31478 & Below

Incoming power supply Check breakers/ reset if required call Power company

if needed

Oven fan switch Check continuity between switch terminals.
Hi-limit thermostat(s), control
box

Fan fuse Check, replace if necessary.
Fuseholder Check, replace if necessary.
Oven fan relay Check for power to coil of oven fan relay. If no voltage

Capacitor(s) Check for opens, shorts, or grounds.
Motor(s), main fan Check for opens, shorts, or grounds.
Fan switch (SEE OVEN FAN WILL NOT RUN.)
Hi-limit thermostat(s)
Oven fan relay
Cooling fan(s) Supply voltage should now be at these motors. If

Incoming power supply Check circuit breakers, reset if needed. Call power
Cooling fan thermostat(s) Check the cooling fan thermostat.(thermostat closes

Cooling fan(s) Supply voltage should now be at these motors. If

Gas supply Check for adequate gas supply to oven.
Manual gas shut off valve Check to see that the manual gas shut off valve is

Fan switch Check to see that the fan switch is on.
Main oven fan Check if main oven fan is operating. If not, refer to

Fuse, burner 3A. Check, replace if necessary. Serial Number
Fuseholder

Check, replace if nece ssary.

Terminals are normally closed, if open, reset
thermostat and test oven for proper operation. If it will
not reset, replace thermostat.

is present, trace wiring back to hi-limit thermostat.
Check for supply voltage at terminal #6 of the relay. If
no voltage is present, trace wiring back to fuse holder.
If voltage is present, at the relay coil, check to insure
the contacts are closing.

voltage is present, check motor for open, shorts, or
grounds. WITH POWER OFF: check for locked rotor.

company if needed.
at 120°F and opens at 100°F). With the cooling fan

thermostat preheated, check for continuity. If switch is
open, replace.

voltage is present, check motor for opens, shorts or
grounds. WITH POWER OFF: Check for locked rotor.

open. Also check flexible gas line connection for any
damage.

“Oven fan will not run”.

present, trace wiring back to the control box hi-limit
thermostat(s). If voltage is present, check to insure
contacts are closing. Replace relay as needed.

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Gas pressure switch (internal to
gas valve)

Oven air pressure switch Check for supply voltage on both sides of switch. If

Hi-limit thermostat Terminals are normally closed. If open, reset and test

Ignition control Check for supply voltage to ignition control at terminal

Burner reset switch Switch is normally open. Check to see that the switch

Burner blower motor Check for supply voltage to burner blower motor.

Burner blower motor Air
pressure switch

Spark generator After a pre-purge time of 30 to 60 seconds after

Igniter/sensor assembly Check for visible damage to igniter/ sensor assembly.

Gas valve Check for supply voltage to gas valve. If there is no

Check for supply voltage to neutral on both sides of
switch. If voltage is present on one side of switch only,
check the following. Check for proper gas pressure
supply to gas valve.(Marked on oven spec. plate.)
Check for proper adjustment of gas pressure switch,
should be set at 10 for Nat., 27 for LP, or 4.5 for town
gas. Check gas filter in gas valve for blockage or
damage. (See Adjustment section for location.) If the
above checks OK, but switch is still not closed replace
gas valve.

voltage is present on one side only, check for air tube
blockage. Adjust air pressure switch. If the above fails,
replace air pressure switch.

oven for proper operation. If thermostat will not hold
for maximum oven temperature, and oven is not
exceeding maximum temperature dial setting, check
for proper location of capillary bulb in its spring holder
If above checks OK, replace hi-limit.

#1 and neutral. If voltage is not present, trace wiring
back to hi-limit thermostat. Check for supply voltage at
terminal #6 to neutral. If no voltage is present, wait 30
seconds and check reset button. If above fails,
replace ignition control.

closes when reset button is pushed. Replace as
needed.

WITH POWER OFF: Turn blower wheel to check for
locked rotor. If supply voltage is present and motor
does not run, replace motor.
Check for supply voltage switching to terminal
N.O. as the air pressure switch closes. Check for air
tube blockage or misalignment, adjust air pressure
switch. If the above fails, replace air pressure switch.

blower motor starts, check for supply voltage to spark
generator. If voltage is not present, Check reset
button located on rear of control box. If voltage is still
not present, replace ignition control. If voltage is
present, visually check for spark at igniter head.

If there is no visible damage to the components, and
no spark, replace the spark generator. If there, is
visible damage to the igniter/sensor assembly,
replace. Also check for frayed or damaged wires in
burner tube.

voltage present, check reset button, check all
connections for tightness. If there still is no voltage at
gas valve, replace ignition control. If there is voltage
present, check for gas pressure at gas pressure tap
located in gas piping at burner manifold. If there is no
gas pressure, replace gas valve.

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Flame will not stay
on

Flame sensor To check for flame sensor operation, connect a digital

multimeter (capable of measuring D.C. micro amps) in
series with the flame sensor wire and ignition control.
Sensor current is 3 micro amps D.C. minimum. NOTE:
The D.C. micro amp test must be conducted with the
oven in low flame (bypass) operation. Turn the
temperature control to its lowest setting. If these
readings are not achieved, replace igniter/sensor
assy. Also, check for any type of damage to flame
sensor wire and connections.

Ignition control If there is sufficient flame sensor current, but the

burner will not remain ignited, check the reset button
on ignition control. NOTE: Check for proper polarity of
the power supply. If all of the above are OK, replace

ignition control.
Oven will not heat
Serial Number
L31479 and above

Oven power relay Check for line voltage to the relay coil. If no voltage is

present, trace wiring back to the control box hi-limit

thermostat(s). If voltage is present, check to insure

contacts are closing. Replace relay as needed.
Fuse, burner, 3A Check, replace if necessary.
Fuse holder Check, replace if necessary.
Air pressure switch Check air switch terminals for supply voltage to

terminals C and NO. If voltage is present on one side

only, check for air tube blockage or misalignment. If

these check okay, adjust air pressure switch, or

replace air pressure switch as needed.
Oven cavity hi-limit thermostat Terminals are normally closed, opens at 350˙C (660˙F).

If open, reset and test oven for proper operation. If

thermostat will not hold for maximum oven temperature,

and oven is not exceeding control setting, check for

proper location of capillary bulb in its spring holder. If

above checks are okay, replace hi-limit thermostat.
Ignition control Check for proper supply voltage to ignition control.

Check for proper voltage to the burner blower motor.

This can be checked at motor connecting plug

terminal 5 and Neutral. If voltage is present, proceed

with next test, if not, wait 30 seconds, push reset

button and try to restart. If this fails, check wires from

burner blower motor to the ignition control. If the

above checks okay, replace ignition control.
Burner blower motor Check for supply voltage to motor.

WITH POWER OFF: Turn blower wheel to check for

locked rotor. If supply voltage is present at motor

connecting plug terminal 5 and Neutral, and motor

does not run, replace burner blower motor.
Air pressure switch

(burner motor)

Check for proper supply voltage switching from “NC”

to “NO” on the air pressure switch. Check for air

pressure switch adjustment, air tube blockage or

misalignment. If these adjustments fail, replace air

pressure switch.
Ignition control A pre-purge time of 30 to 60 seconds occurs after

burner blower motor starts. Check for high voltage

spark output from the ignition control. If there is no

high voltage spark output, check reset button for

ignition control. If there is still no high voltage output,

replace the ignition control.

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Igniter/sensor assembly Check this assembly for visible damage. Replace as

needed. If there is no visible damage, check for
voltage supply to igniter/sensor assembly. If there is
voltage supplied to the igniter/sensor, but there is no
spark, replace the igniter/sensor assembly.

Gas valve Gas valve should open as the ignition control

generates the high voltage spark. Place a manometer
on the pressure tap fitting (located in the gas piping
just prior to the burner manifold) and check for gas
pressure. If valve does not open, check reset button
on ignition control, and all connections for tightness. If
there is still no gas pressure, remove the ignition
control from the gas valve. Check the coils of the gas
valve for opens or shorts. Readings should be as
follows: V1 – 2.9K ohms approx., V2 – 1.3K ohms
approx. If these readings are not achieved, replace
gas valve. If these readings are achieved, replace

ignition control.
Flame will not
stay on

Flame sensor To check for flame sensor operation, connect a digital

multimeter (capable of measuring D.C. microamps)

between the flame sensor wire and the flame sensor

connection on the ignition control. Sensor current is to

be 0.9 microamps, minimum. If these readings are not

achieved, replace the igniter/sensor assembly. Also

check for any type of damage to the flame sensor wire

and connections.

NOTE: The D.C. microamp test must be conducted

with the oven in low flame (bypass) operation
Power supply Set the temperature to the lowest temperature setting.

If there is sufficient microamp current, but the flame

will not stay lit, check for proper polarity of the power

supply.
Ignition control If there is sufficient microamp current, and there is

proper polarity of the power supply, but the burner will

not stay lit, check the reset button for the ignition

control. If the above test is okay, replace ignition

control.
NOTE: Flame should be on at

this time
Low flame is on,
But no main flame

Control transformer Check for supply voltage to the primary of the control

transformer. If no voltage is present, trace wiring back
to the oven power relay. If primary voltage is present,
check for 24VAC at the transformer secondary. If
there is primary voltage, but no secondary voltage,
replace control transformer.

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Oven control Check for 24VAC supply to control. If no voltage is

present, trace wiring back to control transformer. If
24VAC is present, check for a read-out on the control
display. If there is 24VAC supplied, but there is no
read-out on the control display, replace the oven
control.
If there is a read-out on the control, set the control to
maximum temperature (see installation operations
manual for temperature adjustment). With the control
set at maximum temperature, check for line voltage at
the temperature regulation valve. If there is voltage at
the temperature regulation valve, proceed to
“temperature regulation valve” for next check. If there
is no voltage at the temperature regulation valve,
trace wiring back to the oven control. If there is no
voltage output at the oven control, check the read-out
on the control. If the control reads “LP FAIL” or “RP
FAIL”, this indicates that the thermocouple has failed
or has become disconnected from the control. “LP
FAIL” indicates a problem with the left thermocouple
probe, and “RP FAIL” indicates a problem with the
right thermocouple probe.

Thermocouple probe Check to be sure that the thermocouple is securely

connected to the oven control. If the thermocouple is
connected to the oven control, and the control
indicates “LP FAIL” or “RP FAIL”, disconnect the
thermocouple from the oven control and measure the
resistance of the thermocouple. The left thermocouple
should read approx. 21Ω. The right thermocouple
should read approx. 11Ω. If these readings are not
achieved, replace the thermocouple. If these readings
are correct, proceed.

Oven control If the thermocouple checks good, but the oven control

display indicates that there is a thermocouple failure,
replace the oven control. If the oven control indicates
a temperature reading but the oven will not heat,
proceed.

Thermocouple WITH POWER ON AND THERMOCOUPLE

ATTACHED TO THE OVEN CONTROL: Measure the
DC millivolt output of the thermocouple. Refer to the
thermocouple chart (located in the “Removal” section
of the manual) for proper millivolt readings. If these
readings are not achieved, replace thermocouple.

Oven control If the thermocouple checks good, but there is no

voltage output to the temperature regulation valve,
replace the oven control. If there is voltage output to
the temperature regulation valve, proceed.

Temperature regulation valve Check for line voltage supplied to the temperature

regulation valve. If no voltage is present, trace wiring
back to the oven control. If voltage is present, listen
for the valve to open and close. Also check for opens
or shorts in the operating coil. Replace temperature
regulation valve as needed.

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