| Switch, Main Power | WITH POWER OFF: Check continuity between switch | |
|
| terminals. Replace switch as needed. | |
| 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 voltage is present, check for | |
|
| 24 VAC at the transformer secondary. If there is | |
|
| primary voltage but no secondary voltage, replace | |
|
| control transformer. |
|
| Air pressure switch | Check for 208/240VAC to the air pressure switch. If no | |
|
| voltage is present, trace wiring back to main power | |
|
| switch. This normally open switch should close when | |
|
| the main fan is activated. Refer to the “Removal and | |
|
| installation” section for proper adjustment. Replace as | |
|
| needed. |
|
| Switch, Infrared heater | Check for 208/240VAC to the Infrared heater switch. If | |
|
| no voltage is present, trace wiring back to the air | |
|
| pressure switch. WITH POWER OFF: Check continuity | |
|
| between switch terminals. Replace switch as needed. | |
| Conveyor motor | Check for supply voltage to the conveyor motor. If no | |
|
| voltage is present, trace wiring back to the primary of | |
|
| the control transformer. If voltage is present and the | |
|
| motor will not run, check the motor windings for opens | |
|
| or shorts. |
|
|
| WITH POWER OFF: Check the motor windings as | |
|
| follows: |
|
|
| Grey to black - 236 ohms | approx. |
|
| Grey to brown - 236 ohms | approx. |
|
| Brown to black - 472 ohms | approx. |
|
| If any of the above fails, replace conveyor motor. | |
| Capacitor, conveyor motor | Check for shorts or grounds. Replace capacitor as | |
|
| needed. |
|
|
| WARNING: Capacitor has a stored charge, discharge | |
|
| before testing. |
|
| Switch, conveyor reversing | Check continuity between switch terminals. Replace | |
|
| switch as needed. |
|
| Oven control | If there is supply voltage to the motor, and the motor, | |
|
| motor capacitor, and reversing switch check good, | |
|
| replace the oven control. |
|
Conveyor motor runs, but there | Oven control | Check for output voltage from oven control to hall effect | |
is no speed display |
| sensor (sensor is located in conveyor motor). Measure | |
|
| voltage at the motor connector, red wire and yellow | |
|
| wire. Voltage should be approx. 10VDC. If no voltage is | |
|
| present, trace wiring back to oven control. If there is no | |
|
| voltage present at the oven control, replace the oven | |
|
| control. |
|
| Conveyor motor | If there is voltage supplied to the hall effect sensor, | |
|
| check for a frequency output from the hall effect | |
|
| sensor. Measure frequency across the yellow and white | |
|
| wires at the motor connector. Frequency reading | |
|
| should be approx. 25 – 100 Hz. If these readings are | |
|
| not achieved, replace conveyor motor. If the readings | |
|
| are achieved, proceed. |
|
| Oven control | If the hall effect sensor readings are correct, but there | |
|
| is no speed indicated on the display, replace the oven | |
|
| control. |
|
DTF – 1920 Series Service Manual | 9 |