Antunes MT-12 Service Manual

180 Kehoe Blvd.

Carol Stream, Illinois 60188 USA

1-630-784-1000 (Tech Service).

MT-12 TECHNICAL MANUAL

LAST UPDATE 2-15-05

1060004 2/05

MT-12

Muffin

Toaster

Training

MT-12 TECHNICAL MANUAL

LAST UPDATE 2-15-05

1060004 2/05

MT-12 Muffin Toaster

•Warranty

•Toaster warnings

•Toaster installation

•Theory of operation

•Operation instructions

•Toaster maintenance

•Trouble shooting

•Parts Testing & Replacement

procedures

•Wiring Diagram

•Specifications

(Refer to Manual P\N 1010610).

MT-12 TECHNICAL MANUAL

LAST UPDATE 2-15-05

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LIMITED WARRANTY

The Antunes Food Service Equipment Division of A.J. Antunes & Co. provides the following limited warranty to the original purchaser of all McDonald Equipment manufactured and purchased after January 1, 2003. All components are warranted against defects in the material and workmanship for a period of two (2) years from date of original installation, not to exceed 30 month from date of shipment from our factory . If any part becomes defective during the first two (2) years after the original Installation date, Antunes Food Service will pay negotiated straight time labor costs to an Authorized Service Agent to replace the part, plus travel expenses up to 50 miles/80 km, 1 hour each way (100 miles/ 160 km, 2 hours round trip).

WARRANTY EXCLUSIONS:

•The cost of Installation.

•Equipment that has been damaged due to shipment.

Purchaser should make damage claim directly upon carrier

•Alteration, misuse, abuse.

•Improper storage or handling.

•Improper maintenance.

•Failure to follow proper Installation instructions, including

electrical connection.

•Improper or unauthorized repairs.

Antunes Food Service reserves the right to make changes in design or add improvements on any products. The right Is always reserved to modify Equipment because of factors beyond our control and government regulation. Changes to Equipment do not constitute a warranty charge.

This warranty is exclusive and is in lieu of all other warranties, expressed or Implied, including any Implied warranty of merchantability or fitness for a particular purpose, each of which is expressly disclaimed. The remedies described above are exclusive, and in no event shall A.J. Antunes & Co. or any of its Divisions be liable for special consequential or Incidental damages for the breach or delay in the performance of this warranty

•Scheduled Maintenance procedures as outlined in your MRC Card.

•Consumables such as Grill Covers (Release Sheets), gaskets, Conveyor Belt

Wraps, O’Rings, and light bulbs.

•Overtime or Holiday charges.

•Mileage over 50 miles/80 km (100 miles/160 km round-trip), or travel time

over two (2) hours.

•Freight, foreign, excise, municipal or other sales or use taxes.

•Consequential damages such as loss of profit, loss of time, the cost of

repairing or replacing other property which is damaged, or any other incidental damage of any kind.

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WARNING

To avoid possible injury and/or damage to the unit, inspection, test and repair of electrical equipment should be performed by QUALIFIED SERVICE PERSONNEL. The unit should be unplugged when servicing, except when electrical tests are required. Use extreme care during electrical circuit tests. Live circuits will be exposed.

MT-12 TECHNICAL MANUAL

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WARNING

If the supply cord is damaged, it must be replaced by the manufacturer or its service agent or a similarly qualified person in order to avoid a hazard.

WARNING

Do not use an extension cord with this appliance.

WARNING

Do not modify the power supply cord plug if it does not fit the outlet, have a proper outlet installed by a qualified electrician.

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Check with a qualified electrician if you are in doubt whether the appliance is properly grounded or not.

WARNING

Do not clean this appliance with a water jet.

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TECHNICAL THEORY OF OPERATION

MT-12

When the power switch is turned on, line voltage flows to the blower motor & the primary side of the step down transformer (Terminals 1 & 5). This transformer has 2 secondary output coils. The two top terminals, 6 & 7 (Black wires) supply 10-12 VAC. The two bottom terminals, 9 & 10 (Brown wires) supply 6-8 VAC to the control board input terminal P1. During the power up sequence, the unit performs a self test. Two (2) beeps, not followed by any additional beeps indicate a successful test. If certain faults were detected, the unit will begin to beep 2-5 times wit h a 2 second pause between beeps (See Beep Codes).

This control board has 2 modes of operation, Standby Mode & Toast Mode. In Standby Mode (Unit Idling), the heater assembly, which consists of a left & right side coil, will partially heat to maintain the toast chamber hot. It generates approximately 4-6 fluctuating amps during standby. Its voltage will also fluctuate between 0-50 VAC when measured with a VOM across the SS relay output terminals A2 & B2. In toast mode, the heaters intensify to full power generating approximately 15.5-17 amps. The voltage will fluctuate between 140-200 VAC across the SS relay output terminals A2 & B2.

The control board calls for heat by supplying .5-1.5 VDC (During Standby) or 3.5-7.0 VDC (During Toast Mode) to the SS relay input terminals (+ - + - ). Once powered, the relay closes terminals Al to A2 & B1 to B2 which allow VAC to flow to the heater assembly.

As the toast chamber begins to heat up, a type “K” thermocouple monitors the toast chamber temperature. The temperature, in conjunction with the toast time, is controlled by the control board. When the front door is closed, the green ready light will turn on and the unit will beep once to indicate the start of a toast cycle. Provided that the amber light (Partial Load) is off, the unit will run a full load (4-6 muffins) toast c ycle. At the completion of a full load cycle (normally 60-90 seconds), the unit times out, begins to beep, and the green ready light begins to flash until the door is opened. If the door remains open at anytime, the unit goes into standby mode. When the door is closed and the partial load switch is pushed, the amber light (Partial Load) will turn on to indicate the start of a partial load (1-3 muffins) cycle. At the completion of a partial load cycle (normally 55-85 seconds), the unit times out,

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THEORY CONTINUED

begins to beep, and the green ready light begins to flash until the door is opened once again. NOTE: You must press the partial load switch again if you would like to deactivate the partial load cycle & amber light.

The toast times for both the partial load & full load may be adjusted to allow for a lighter or darker

roduct. The appropriate potentiometer at the rear of the unit must be rotated clockwise (CW) for

longer toast times or counter clockwise (CCW) for shorter toast times. If the heating circuit continues to call for heat and the toast chamber overheats, a manual resettable

Hi-Limit Thermostat will trip and open the heating circuit. If the Hi-Limit requires repeated resetting, the root cause must be determined.

COMPONENT DESCRIPTION & FUNCTION:

Power Switch: Turns main power On or Off to the unit’s circuitry. Blower motor : Helps cool the exterior top, side panels, & electrical compartment by circulating

ambient air through louvers.

Transformer: Steps down the incoming supply voltage to operate the control board. Control Board: Operates & controls all timing, signaling, diagnostic, & heating functions. Heater Assembly: Consisting of left & right side coil, it generates the radiant heat to toast the

roduct.

Hi-Limit: Breaks & opens the heating circuit if the toast chamber overheats. Double Pole Single Throw (DPST) Relay: When both of its input coils (+ - +-) are powered by

VDC from the control board, it closes terminals Al to A2 & B1 to B2 which allow VAC to flow to the heater assembly. NOTE: The VAC will fluctuate between 0-50 VAC during standby mode & 140-200 VAC during toast mode.

Thermocouple: Monitors the toast chamber temperature and relays it to the control board. The control board will then adjust the toast time accordingly.

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THEORY CONTINUED

Door Micro Switch: When closed, it signals the control board to initiate a toast cycle. NOTE: The unit will initiate a full load cycle if the amber light is off . It will initiate a partial load

cycle if the amber light is lit. Partial Load Switch: When closed, it signals the control board that a partial load cycle has been

chosen. It will also turn on the amber light. Full & Partial Load Timers (Pots): Located on the control board and accessible from the

exterior rear. When rotated clockwise (CW), it extends the toast time. If rotated counter clockwise (CCW), it decreases the toast time. These Pots have built in stops and are initially set to 12:00 o’clock at the factory. They are adjustable from 7:00 to 5:00 o’clock. NOTE: turning them beyond their stops will permanently damage them.

Green “ready” light: Will be lit whenever the unit is in a toast cycle (full or partial). The light will blink at the completion of a toast cycle until the door is opened.

Amber light: Will be lit to indicate that the unit is in a partial load. Note: The unit will start a partial load toast cycle only if the amber light is lit and the door is closed.

Toast chamber: Compartment where the product is placed for toasting.

MT-12 TECHNICAL MANUAL

LAST UPDATE 2-15-05

1060004 2/05