Vulcan VO004 Service Manual

SERVICE AND PARTS MANUAL

FOR ELECTRIC BAKE AND ROAST OVENS

MODELS V0004 & V0008

FORM 30741 (9 -92) (Formerly 112637)

VULCAN-HART COMPANY, P.O. BOX 696, LOUISVILLE, KY 40201-0696, TEL. [phone]

SERVICE AND PARTS MANUAL
ELECTRIC BAKE & ROAST OVENS
MODELS V0004 & V0008 INDEX

PLEASE KEEP THIS MANUAL FOR FUTURE REFERENCE

Your Vulcan oven is produced with quality
workmanship and material. Proper installation, usage
and maintenance will result in many years of
satisfactory performance.

DESCRIPTION PAGE
INDEX 3
TROUBLESHOOTING 4,5
CALIBRATING ELECTRIC CONTROLS 6
PARTS DESCRIPTION AND REPLACEMENT 7, 8

PARTS LIST 9-22

The manufacturer suggests that you thoroughly read this
entire manual and carefully follow all of the instructions
provided.

TROUBLESHOOTING

The following is a guide for troubleshooting procedures and
covers some of the more common problems that may
develop. Servicing personnel need to become familiar with
the circuit and components in order to follow a logical
sequence of troubleshooting and to make repairs not
mentioned in this troubleshooting guide.

Remember that the two 3-heat switches control not only the
rate of temperature build-up in the oven, but the amount of
heat that is applied to their sections (top or bottom); therefore,
the operator can control the needed heat for a particular meal
by both its position inside the oven, as well as by varying the
3-heat switch setting.

The instruments required for troubleshooting are:

1. A.C voltmeter to measure line voltages up to 500 volts.

2. A.C. ammeter to measure line currents.

3. Accurate thermometer to measure temperature.

PROBLEM CORRECTIVE ACTION
No heat in any sections.

Check the main supply breaker or fuse.

No heat in one section only. Check voltage on the terminal block of the cool section. Follow 1 or 2

below.

1. If no voltage, check for loose or wrong connection of the interconnecting
leads.

2. If 208 volt, check, voltage between lead 3 and 6 or A3. Follow A or B
below.
A. If no voltage, check for bad connection to, or a tripped or failed
circuit breaker.
B. If 208 volt, measure voltage between 6 and 12 and between A3 and

11. If no voltage, check the thermostat. If 208 volt, check the
voltage between terminals 2 and 1 of the 3-heat switch (set the
switch on HI position). If no voltage, check for problem with the
switch. If 208 volt, check the elements for either open circuit or bad
connection.

Heat in bottom section only. Measure voltage between L2 and L3 terminals of the top 3-heat switch.

Follow 1 or 2 below.

1. If 208 volt, measure voltage between terminals 2 and 3 of the switch
(with switch set on HI position). Follow A or B below:
A. If no voltage, replace switch.
B. If 208 volt, check for opened elements or bad connection in leads
17,18,19.

2. If no voltage, check the thermostat and supply voltage as outlined in NO
HEAT IN ONE SECTION ONLY above.

In the following table, the voltmeter is used to measure the
voltage between two phases on 208, 240 and 480 volts, and
between the phase and the neutral on 220/380 and 240/415
volt supplies. Do not measure the voltage with respect to the
chassis ground. For the sake of simplicity, the measured
voltage is referred to 208 volt, assuming that the supply is
208 volt. When the supply is 220, 240 or 480 volt, the
measured voltage should also be 220, 240, 480 volts. Refer
to the appropriate wiring diagram for reference.

The fact that the voltmeter indicates presence of voltage does
not mean that the current is flowing. To be sure of optimum
function, an ammeter sh ould be used to determine the exact
amount of current going through the elements. Check the
supply current going to X, Y, or Z terminals and compare it
with the required value shown on the wiring diagram or the
rating decal (attached to the breaker cover) for the particular
supply voltage and phase.

With the main power ON, 3-heat switches set at HI, and the
thermostat set at about 400°F:

PROBLEM CORRECTIVE ACTION
Heat in top section only. Follow the same procedure for the bottom 3-heat switch as outlined in HEAT

Oven temperature not Recalibrate the thermostat, following the instructions in RECALIBRATING

No oven lights (all models Since the two 25 watt, 120 volt bulbs are connected in series to the 208-240
except pizza oven). volt supply, a problem with either bulb will result in no lights. Replace both

208 volt models: Check for problem with breakers or bad connections to

480 volt models: Measure voltage between leads 4 and 31.

bad connection to the terminal block.

IN BOTTOM SECTION ONLY above.

ELECTRIC CONTROLS in this manual.

bulbs with two good ones. Make sure the bulbs are tight inside the socket.
If still no light, measure the voltage between leads 4 and 8 going to the
switch.
If 208 volt, check for problem with switch or bad connections to the switch
and to the lamp sockets.
If no voltage, proceed as follows:

breakers.

1. If 230 volt, check for problem with the breaker.

2. If no voltage, measure voltage between lead 32 and the transformer
lead connected to the end terminal of the breaker.
A. If 480 volt, check for problem with transformer.
B. If no voltage, measure between leads 32 and 33 on the breaker
terminal. If 480 volt, the breaker is bad. If no voltage, check for

CALIBRATING ELECTRIC CONTROLS

Fig.1

Robertshaw electric thermostats are adjusted at the factory
and calibrated on precision instruments to control
temperatures accurately. Adjustment or recalibration is not
needed unless the thermostat has been mishandled in transit,
or changed or abused while in service.
TO CHECK CALIBRATION

1. Use a Robertshaw test instrument or a good grade oven
thermometer and place thermocouple or thermometer in
center of oven.

2. With thermostat dial in the OFF position, make certain OFF
mark on the dial agrees with reference point of the bezel
or panel; misalignment will affect calibration. Then turn
the dial to a medium temperature setting.

4. After the control has cycled thermostatically three or more

TO CALIBRATE

5. Turn control to OFF position and remove dial.

6. With screwdriver, turn screw "A" clockwise to decrease and

7. Replace dial.

times, note the oven temperature when the electric unit
snaps off, and the oven temperature when it snaps on.
Recalibrate only if the average of these two temperature
readings varies more than ±20°F of the dial setting.

counterclockwise to increase the temperature. A 1/4 turn
of screw "A" causes a temperature shift of 35°F (Fig. 1).

3. Allow oven to heat until control snaps ON and OFF
thermostatically at least three times. This will allow oven
temperature to stabilize and eliminate possible error
resulting from initial oven temperature overshoot and/or
undershoot.

After calibration is made, allow oven to operate until
temperature has stabilized, then recheck to determine
whether or not the calibration has been corrected.

PL-501 119|

PARTS DESCRIPTION AND REPLACEMENT

WARNING: DISCONNECT ELECTRICAL POWER SUPPLY

BEFORE SERVICING.
Reconnect the leads to the replaced component exactly as to

the original (refer to the wiring diagrams for each model).

SWITCH PANEL

Thermostat

A DPST cycling switch, with its normally closed contacts,
provides power to the two non-cycling 3-heat switches, which,
in turn, turns on the heating elements. Once the set
temperature is reached, the contacts open and the elements
are turned off. The thermostat used in pizza ovens has a
maximum temperature limit of 700°F. The thermostat used in
all other models has a limit of 500°F.

To replace the thermostat, remove the bulb from under the
mounting clips inside the oven. Pull out the capillary through
the hole on the right -hand oven wall, loosen the two mounting
screws of the thermostat, and remove it from the switch
panel.

To recalibrate the thermostat, follow the instructions in
CALIBRATING ELECTRIC CONTROLS in this manual.

3-Heat Switch
A double-pole, 4-position sw itch connects the supply power at

its input (L2, L3 terminals) to the elements at its output
(terminals 1, 2, 3) in such a way as to provide full power
(elements connected in parallel) to about half of full power
(only one element connected) to about one-fourth of full
power (elements connected in series) as it rotates from HI to
MED to LO positions. At the OFF position, all connections are
opened. Therefore, the position of the 3-heat switch
determines the rate of temperature rise, while the thermostat
controls the temperature limit. The 3-heat switches used in
208-240 volt and 480 volt models, though physically looking
different, electrically are identical. The following diagrams
show the proper connection for each model:

HI position: L2 connects with 2

MED position: L2 connects with 2

LOW position: L2 connects with 3

OFF position: All connections open

To remove the switch, loosen the nut on the shaft and pull it
out from the back of the switch panel.

Signal Light

The light ON indicates that the thermostat contacts are
closed, providing power to the 3-heat switches. The light goes
off when the set temperature is reached. While maintaining at
set temperature, the light cycles on and off.

To replace the bulb, unscrew and remove the lens to reach
the bulb.

To replace the socket assembly, loosen and remove the nut in
the back of the switch panel, then pull the socket out from the
front.

L3 connects with 1 & 3

L3 connects with 1

L3 connects with 1

NOTE: On 480 volt models, make sure that a 300K ohm
resistor is added in series with the light.

To replace bulbs, remove the four screws mounting the
window assembly to the oven wall.

NOTE: Make sure that the bulb is 25 watt and the
gasket is in good condition.

Element Assembly

2. 480 Volt Model
Remove the breaker closure in order to reach

the components.

A. Terminal Block — Used for field or

interconnecting supply leads. To replace,
remove the two mounting screws.

The inner and outer elements in the top or bottom
section of the oven are connected together by a jumper
strap on one end (common junction, connected to
terminal 2 of the 3-heat switch). The voltage and
wattage rating is stamped on each element (see wiring
diagrams for detail).

Replace the elements from inside the oven as follows:

1. Top Elements
Remove the element terminal cover and loosen the

bolts and nuts to disconnect the end straps from the
element terminals. Remove the retainers holding the
elements to the frame and slide the element out of
the frame assembly.

2. Bottom Elements
Remove the oven hearth by removing the three

slotted head bolts. Lift front of the hearth and pull it
out of the oven. To replace the elements, follow the
same procedure described in Item 1 above.

Connection Block Assembly

1. 208 and 240 Volt Models
Remove the breaker closure in order to reach the

components.

B. Porcelain Block — Used as a junction for
wires going to the oven lights.

C. Breaker — The coil of the relay trip breaker is

connected in series with the primary of the
control transformer, and the switches of the
breaker are connected in series with the
secondary winding of the transformer.
Overload in the coil of the breaker causes
the switch to trip open, turning off the
control circuit (secondary of the
transformer).

To replace, remove the two mounting screws.

D. Transformer — The 460 to 230 volt, 200 VA

control transformer steps down the supply
voltage for the oven light circuit.

To replace, remove the four mounting screws.

NOTE: When replacing the transformer,
make sure that terminal H2 is connected to
H3 and terminal X2 to X3 by means of the
metal jumper strap or jumperwire lead.
ConnecttoH"! andH4 terminals (primary or
input) the 480 volt supply leads, and
connect to X1 and X4 terminals (sec ondary
or output) the 240 volt leads for the light
circuit. See the 480 volt wiring diagrams for

A. Terminal Block—Used for interconnecting or field

supply leads. To replace, remove the two
mounting screws.

B. Porcelain Block — Used as a junction for wires
going to the oven lights.

C. Breakers — The 15 amp. breakers protect the

lights and thermionic (fan) circuit. The 50 amp.
breakers protect the heating elements. To
replace, remove the two mounting screws.

detail.

Timer

Remove the knob and the lockwasher from outside the
oven. Remove the timer body from inside the control
compartment.