Garland MCO-GS-10E, MCO-GS-10M, MCO-GD-10E, MCO-GD-10M User Manual

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GARLAND

A WELBILT COMPANY

BUILT TO LEAD... BUILT TO LAST

SERVICE MANUAL THE “MASTER” GAS CONVECTION OVENS

Models covered in this manual are:

MCO-GS-10M:

MASTER CONVECTION Oven - GAS STANDARD DEPTH -(10)SINGLE DECK Manual CONTROL

MCO-GS-10E:

MASTER CONVECTION OVEN - GAS STANDARD DEPTH -(10)Single DECK ELECTRONIC CONTROL

MCO-GD-10M:

MASTER CONVECTION Oven - GAS DEEP DEPTH -(10)SINGLE DECK Manual CONTROL

MCO-GD-10E:

MASTER CONVECTION Oven - GAS DEEP DEPTH -(10)SINGLE DECK ELECTRONIC CONTROL

GARLAND Commercial Industries, Inc.

185 East South Street Freeland, Pennsylvania 18224

DIRECT “ON-SITE” SERVICE 1-800-451-1165 GENERAL INFORMATION 1-800-424-2411

FORM #GCI-MCOVN

PRINTED IN THE U.S.A.

This service manual is designed to answer questions related to model operational requirements, troubleshooting and disassembly/assembly procedures. It contains electronic ignition operation, troubleshooting and electronic control operations that include diagnostic codes, ladder diagrams, wire diagrams and troubleshooting. It also includes BTU ratings, orifice size and gas pressure technical data for each model.

For example; if you need to know information on manual controls (manual controls - controls the oven with hydraulic thermostat, electric mechanical timer.) refer to SECTION 2: OVERVIEW OF OPERATIONAL SEQUENCES, Sequence of Operation. This book is broken down into sections, each section will list the applicable topics. Use the Table of Contents to locate the topic and function that you are attempting to trouble-shoot.

Table of Contents

 

SECTION 1: SPECIFICATION & DIMENSIONS ............................................................................

3

GAS CONVECTION OVEN "GAS SPECIFICATIONS”........... ....................................................................................

4

DIMENSIONS & SPECIFICATIONS ............................................................................................................................

4

SECTION 2: OVERVIEW OF OPERATIONAL SEQUENCES .......................................................

4

MANUAL CONTROLS - "M” .............................. .........................................................................................................

5

Sequence of Operation.............................................................................................................................................

5

Manual Ladder Diagram ...........................................................................................................................................

5

CALIBRATION OF THERMOSTAT .............................................................................................................................

5

Instrumentation.........................................................................................................................................................

5

Weighting..................................................................................................................................................................

6

Thermostat Operation...............................................................................................................................................

7

ELECTRONIC CONTROLS - “E” .......................... ......................................................................................................

8

Sequence of Operation (With the Oven Doors Closed) ...........................................................................................

8

Electonic Ladder Wire Diagram................................................................................................................................

8

ELECTRONIC CONTROL FAILURE CODES .............................................................................................................

9

CHART FOR INTERNAL OVEN TEMPERATURE SENSOR......................................................................................

9

ROBERTSHAW COM6000 CONTROLLER................................................................................................................

9

USER PREFERENCE OFFSET FOR THE ELECTRONIC CONTROLLERS ...........................................................

10

COM6000 UPO MODE...........................................................................................................................................

11

COM6700 UPO MODE...........................................................................................................................................

11

ELECTRONIC PILOT & MAIN BURNER IGNITION SEQUENCE ............................................................................

12

FIRST STAGE - TRIAL FOR PILOT IGNITION .....................................................................................................

12

SECOND STAGE - MAIN BURNER OPERATION ................................................................................................

12

SAFETY LOCKOUT TIME......................................................................................................................................

12

SERVICE ....................................................................................................................................................................

13

PRELIMINARY CHECK..........................................................................................................................................

13

SYSTEM TROUBLE SHOOTING...........................................................................................................................

13

S86 CHECKOUT AND TROUBLE SHOOTING .....................................................................................................

14

CHECK SPARK IGNITION CIRCUIT .....................................................................................................................

15

CONTROL MODULE FLAME SENSOR CIRCUIT.................................................................................................

15

2

SECTION 3: COMPONENT ACCESS OF FUNCTIONAL COMPONENTS..................................

16

DOOR GASKET REPLACEMENT............................................................................................................................

17

TO REMOVE DOORS FROM THE OVEN................................................................................................................

18

INSTALLATION OF OVEN DOORS .........................................................................................................................

19

INSTALLING AND ADJUSTMENT OF THE DOOR CHAIN.....................................................................................

19

DISASSEMBLY OF THE LEFT DOOR.....................................................................................................................

19

DISASSEMBLY OF THE RIGHT DOOR (W/O WINDOW) .......................................................................................

20

TO REPLACE OR ADJUST DOOR LATCH MECHANISM ......................................................................................

22

TO REPLACE CONVECTION OVEN MOTOR ASSEMBLY ....................................................................................

22

CONVECTION OVEN MOTOR ASSEMBLY ............................................................................................................

23

MAIN BURNER, PILOT BURNER & DOOR MICRO-SWITCH LOCATION ............................................................

24

SECTION 4: COMMON WIRE DIAGRAMS .................................................................................

25

SECTION 1: SPECIFICATION & DIMENSIONS

3

Garland MCO-GS-10E, MCO-GS-10M, MCO-GD-10E, MCO-GD-10M User Manual

GAS CONVECTION OVEN "GAS SPECIFICATIONS”

 

 

MAIN

 

 

 

PILOT

GAS

 

TOTAL

BURNER

ORIFICE

PILOT

ORIFICE

PRES. W/C

 

B.T.U.'S

ORIFICE

AMT.

ORIFICE

AMT.

NAT

PRO

 

 

 

 

 

 

 

 

*

 

 

 

NAT

PRO

 

NAT

PRO

 

**

 

 

 

5/64” #55

 

 

 

 

4.5"

 

MCO

40,000

2

.020"

.012"

1

 

10.0"

 

 

(.0781”)

 

 

 

 

 

5.0”

 

 

60,000

5/64” #55

3

.020"

.012"

1

4.5"

10.0"

MCO

 

 

 

(.0781”)

 

 

 

 

 

5.1”

 

 

 

5/64” #55

 

 

 

 

4.5"

 

MCO

80,000

4

.020"

.012"

1

 

10.0"

 

 

(.0781”)

 

 

 

 

 

5.5”

 

* - Gas pressure measured at burner manifold. ** - Gas pressure measured at redundant gas valve pressure tap.

All models (single deck ovens) amperage rating is 6.2 (each oven). Manifold size is ¾" N.P.T. (National Pipe Thread). NOTE: Two-speed motor, 1140 and 1725 R.P.M., 60 Hz, clock-wise motor rotation looking into oven cavity. NOTE: Each deck supplied with a 6 ft. power supply cord for 120-volt units.

DIMENSIONS & SPECIFICATIONS

 

 

 

 

 

 

 

 

 

1-1/2

 

 

 

 

 

 

[38mm]

 

1-1/2

1/2 N.P.T.

 

 

 

 

 

[38mm]

[13mm]

7-3/4

 

1-7/8

 

 

 

GAS INLET

 

 

 

 

 

[48mm]

 

 

 

[197mm]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

REAR GAS INLET

 

 

 

 

 

 

 

32

 

32

 

1-7/16

 

 

[813mm]

 

 

2-3/8 x 5

 

 

3/4 N.P.T.

[813mm]

 

[37mm]

 

 

 

[60mm x 127mm]

 

 

[19mm]

 

 

 

 

 

 

 

 

FLUE

 

 

GAS INLET

57-1/2

 

43-1/4 DEEP

 

38-1/4

 

 

54-9/16

[1099mm] DEEP

 

70-1/2

 

[1461mm]

 

[972mm]

 

[1386mm]

39-1/4 STD

 

[1791mm]

 

 

 

 

 

 

38

[997mm] STD

 

 

32

 

 

 

 

 

[813mm]

 

 

[965mm]

 

 

 

32

35-9/16

25-1/2

 

 

 

 

 

 

 

 

[903mm]

 

 

 

 

[813mm]

[648mm]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

17-3/4

 

 

19

 

 

 

[451mm]

 

 

[483mm]

 

 

38

 

 

 

6-1/2

 

 

 

 

 

[165mm]

 

 

[965mm]

 

 

 

 

 

 

 

 

 

 

Single Deck (Front View)

 

(Top View)

 

[965mm]

 

 

 

 

 

 

38

 

 

 

 

 

 

Double Deck (Front View)

 

 

INTERIOR DIMENSIONS (per oven)

EXTERIOR DIMENSIONS

SHIP WEIGHT/DIM

Model #

W

H

D

W

H (w/legs)

D

Lb./KG

Cu. Ft.

MCO-GS-10

29”(736mm)

24”(610mm)

24”(610mm)

38”(965m m)

57½”(1460mm)

39”(991mm)

510/232

42 cu. ft.

MCO-GS-20

29”(736mm)

24”(610mm)

24”(610mm)

38”(965m m)

70½”(1791mm)

39”(991mm)

1020/464

84 cu. ft.

MCO-GD-10

29”(736mm)

24”(610mm)

28”(711mm)

38”(965m m)

57½”(1460mm)

43”(1092mm)

510/232

42 cu. ft.

MCO-GD-20

29”(736mm)

24”(610mm)

28”(711mm)

38”(965m m)

70½”(1791mm)

43”(1092mm)

1020/464

84 cu. ft.

 

INPUT CHART - Natural or Propane Gas

ELECTRICAL CHARACTERISTICS

 

 

 

KW

 

 

 

 

 

Model #

BTU/HR

Equiv.

Gas Inlet

120V/1 Phase

240V/1 Phase

 

Motor

MCO-GS-10

60,000

17.6

One @ ¾” NPT

One @ 6.2 Amps

One @ 3.1 Amps

 

½ HP

MCO-GS-20

120,000

35.2

One @1” NPT

Two @ 6.2 Amps

Two @ 3.1 Amps

 

½ HP

MCO-GD-10

60,000

17.6

One @ ¾” NPT

One @ 6.2 Amps

One @ 3.1 Amps

 

½ HP

MCO-GD-20

120,000

35.2

One @ 1” NPT

Two @ 6.2 Amps

Two @ 3.1 Amps

 

½ HP

SECTION 2: OVERVIEW OF OPERATIONAL SEQUENCES

4

Understanding the sequence of operation is necessary in properly trouble-shooting this appliance. In this section the sequence of operation will be covered first, as well as calibration and operation of components, and basic trouble shooting techniques for that specific model. Follow each sequence carefully, and get to understand its operation before moving on to trouble shooting.

MANUAL CONTROLS - "M"

Sequence of Operation (Starting with the oven doors in closed position.)

1.Turn the Mode Switch to the “Cook” position. This sends line voltage to the timer. And with the doors closed, line voltage is sent via the door switch to the thermostat and the Hi/Lo Fan switch.

2.Select Hi or Lo speed, the motor will now be operational.

3.Rotate the temperature dial to desired temperature. The thermostat will now call for heat sending line voltage to the 24 volt transformer. With the motor operating, the centrifugal switch is closed, completing the neutral circuit to the transformer.

4.The 24v transformer now sends 24 volts to the ignition module.

COOK

POWER

HIGH

 

 

O

ON

 

 

 

F

 

 

F

 

 

COOL

 

LOW

DOWN

TIMER

 

 

 

TEMP

5. The *ignition sequence starts and oven temperature begins to rise.

*See “Ignition Sequence” later in this manual.

Below is a simplified power diagram:

Hi/Lo Sw.

 

 

 

 

 

 

 

 

 

 

 

 

Hi Speed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hi/Lo Sw.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lo Speed

 

 

 

 

 

 

Door Sw. Mode Sw.

 

 

 

 

 

 

 

 

 

Neutral

 

 

 

 

 

 

 

 

 

 

 

 

 

Timer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

24 Volt

Motor

 

 

 

 

 

 

 

 

 

 

 

 

Line

 

 

 

 

Transformer

Centrif.

Sw.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thermostat

Light Sw.

Ign. Module

CALIBRATION OF THERMOSTAT

INSTRUMENTATION

5

A thermocouple type test instrument is preferred for measuring oven temperatures accurately. Mercury thermometers are acceptable providing they can be proven accurate.

Regardless of the type instrument used, it is most desirable to double-check it just before making an oven temperature check. This can be done simply and quickly by placing the thermocouple tip (or immersing the entire mercury thermometer) in boiling water. Note: Mercury oven thermometers should be the "total immersion type." The resulting reading should be within several degrees of 212°, -depending on the altitude.

Generally, a mercury thermometer can drop in excess of 25° when the doors are opened to check oven tem perature. This condition makes it extremely difficult to get a true temperature reading.

Almost all ranges today have oven burners which cycle "on and off." The high and low points of the resulting temperature "swing" (differential) in the oven must be measured-and averaged-to determine the true operating temperature. A thermocouple type test instrument is best suited to measure these temperature changes quickly and accurately, and without opening the oven door.

With an accurate, thermocouple test instrument or mercury thermometer, it is still difficult to measure these changing oven temperatures and then, average them correctly. This is why we recommend that the thermocouple tip or the bulb of the thermometer be "weighted." Weighting (adding mass) to the test instrument compensates for oven temperature changes by making the test instrument less sensitive to these constant changes in temperature. Note: How this weighting can be done is discussed later.

Measuring these changing high and low temperatures points in an oven is possible with either type of test device without weighting but is subject to possible inaccuracies. This is most true at low temperature setting because, in this area, the function of "time" becomes a factor. The simple averaging of temperatures, then, may not produce the true operating temperature. "Weighting" provides the compensation for both time and temperature that is necessary.

We produced (next page) test curves showing actual results in the low temperature area showing the difference in results when using an unweighted and a weighted thermocouple or thermometer. Tests were made with the same control, same oven and dial at 170° mark (not move d).

Chart No.1

260

240

220

200

180

160

140

120

100

Chart No.2

260

240

220

200

180

160

140

120

100

Unweighted Thermocouple dial setting 170 F

Weighted Thermocouple Dial Setting 170F

From the above, it can be seen that an error of 15° is possible. Chart #1, unweighted thermocouple indicates an erroneous average oven temperature of 185°. Chart #2, weighted thermocouple indicates the "average" or true temperature to be 170°.

WEIGHTING

A thermocouple can be weighted by clamping the tip between two one-inch squares of 1/16" thick aluminum. The thermocouple can also be weighted (just as successfully) by using a letter-size sheet of aluminum foil. Fold the foil

6

five times doubling the thickness with each fold. After the fifth fold, place the thermocouple tip in the center of the aluminum piece and fold once more. Finally, fold in the sides so that the foil clings to the thermocouple tip.

A mercury thermometer can be weighted in much the same way by wrapping several layers of aluminum foil around the bulb end thus creating the necessary mass. This procedure is a must if you open an oven door to check temperature.

THERMOSTAT OPERATION

It is normal for a hydraulic thermostat cycling with a temperature swing of 45° to 50°. When checking calibration first; allow the thermostat to cycle a minimum of four (4) times, second; place your temperature sensor in the geometric center of the empty oven. Once the oven has been allowed to preheat record the temperature at which the burners cycle "ON and OFF". Average the two readings, that average should be +-20° of the set point temperatu re.

Example: Thermostat set point at 300°, first cycl e Off at 325°. Cycle back ON at 291°. The average of 325° and 291° is 308°. This thermostat is with the +-20° to lerance. If the thermostat is cycling beyond the 20° tolerance and the appliance is under warranty recalibrate the thermostat or if not under warranty consult owner for proper action. If the thermostat is out of calibration more than fifty 50°, it will not likely hold an attempt of recalibration, we suggest that the thermostat be replaced.

"B" Dial Shaft

Increase

 

"A" Calibration Screw Head

 

 

Decrease

1/4" Turn

 

- CALIBRATION NOTES -

7

ELECTRONIC CONTROLS - “E”

Sequence of Operation (With the Oven Doors Closed)

1.Line Voltage is supplied to the Mode Switch, Door Switch and the Momentary Light Switch.

2.Set Mode Switch to COOK and close the oven doors. Line Voltage is sent from Mode Switch to power up the Controller and to the AUX relay on the controller. With the oven doors closed Line Voltage is sent to the 24 volt transformer.

3.Set desired temperature. The controller’s relays now close.

4.The AUX relay sends Line Voltage to the motor relay coil, closing the circuit to the Hi/Lo Fan Switch. The motor now operational causes the centrifugal switch to close and send the Neutral Voltage to the 24 Volt Transformer.

5.The bake relay completes the circuit from the 24 volt transformer to the ignition module and *ignition occurs, heating the oven.

Below is a simplified power diagram:

COOK

HIGH

O

HEAT

 

F

 

F

 

COOL

LOW

DOWN

 

- +

- +

START

CANCEL

TIMER

TIMER

TIMER

TEMP

0-12 HOUR

140-500F

 

 

 

 

24 Volt

 

 

 

 

 

Motor

 

 

 

 

Transformer

 

 

Centrifugal

Switch

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

24 V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thermostat

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ign. Module

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Door Sw.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hi Speed

Motor Relay

Lo Speed

Neutral

AUX

Mode Sw.

COM6000

Light Sw.

8

ELECTRONIC CONTROL FAILURE CODES

The GARLAND digital control has a self-diagnostic program. If a problem occurs within the digital controller, you may see one of the "F" codes.

Below is a listing of the "F" codes with explanations:

-F1- Relay output is enabled when not cooking. If this failure code appears in the display, the cook relay may be on even if the control is not cooking. The control should be replaced.

-F2- Over temperature alarm. If this failure code appears in the display the control is sensing an oven temperature 50° or more above the maximum set temperature (500°). This failure may be caused by a faulty sensor.

Check the sensor connection for loose wires.

Replace the sensor and check for proper operation.

If failure continues replace the control.

-F3- Open sensor circuit. If this failure appears in the display, the control is sensing an open circuit at the sensor input. This failure is most often caused by a poor connection or broken sensor.

Check sensor connection and leads for broken wires of loose connections. Replace sensor and check for proper operation. If failure continues replace control.

-F4- Shorted sensor circuit. If this failure appears in the display, the control is sensing a short circuit at the sensor input. This failure is most often caused by loose wires at the connection of shorted sensor leads.

Check sensor connection and leads for loose wires. Replace sensor and check for proper operation. If failure continues replace control.

-F5- Relay outputs not enabled when cooking. If this failure appears in the display the control cannot turn the relays on even when cooking. The control should be replaced.

-F6- No 60 Hz input. The control does not sense the input power. This failure mode is most often the result of a failed component in the control. However, this failure may also be the result of a very noisy power line. Look for any large electrical noise producing machinery (such as mixers, compressors, dishwashers etc.). If possible, turn these machines off. Reapply power to the oven. If the failure repeats, replace the control. If the failure does not repeat, an electronic control may not work in this application because of noise. You must isolate the supply circuit.

-F7- The control has detected that calculated EEPROM check sum is not the same as the expected check sum retrieved from the EEPROM. When the control detects this error code, it will disable outputs before the alarm sounds.

RESISTANCE vs. TEMPERATURE CHART FOR INTERNAL OVEN TEMPERATURE SENSOR

The chart below will provide the Ohms at various temperatures. This will enable you to determine if the temperature probe is operable.

The chart is in Degrees Fahrenheit. How to use chart, for 350°, read down to 300 then across to 50, answer is 1654Ohms of resistance.

TEMP

10°

20°

30°

40°

50°

60°

70°

80°

90°

 

932

953

974

995

1016

 

1038

1059

1080

1101

1122

100°

1143

1163

1184

1205

1226

 

1247

1267

1288

1309

1329

200°

1350

1370

1391

1411

1432

 

1452

1472

1493

1513

1533

300°

1553

1574

1594

1614

1634

 

1654

1674

1694

1714

1733

400°

1753

1773

1793

1813

1832

 

1852

1871

1981

1911

1930

500°

1949

1969

1988

2008

2027

 

2046

2065

2085

2104

2123

ROBERTSHAW COM6000 CONTROLLER

9

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