| Temperature Control | Check for supply voltage at temperature control. If | |
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| no voltage is present, trace wiring back to | |
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| thermostat. Turn the temperature adjustment knob | |
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| to maximum temperature position and check for | |
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| 208/240 VAC at the load terminals 7 and 8. If | |
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| 208/240 VAC is present and unit is not heating, | |
|
| refer to "Mercury Contactor" for next check. If | |
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| 208/240 VAC is not present, proceed. | |
| Thermocouple Probe | WITH POWER ON AND THERMOCOUPLE | |
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| LEADS ATTACHED TO THE TEMPERATURE | |
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| CONTROL BOARD: measure D.C. millivolt output | |
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| of these leads. Refer to thermocouple chart in | |
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| Section D for proper readings. If these readings | |
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| are not achieved, replace thermocouple. | |
| Temperature Control | Disconnect the potentiometer leads from the board. | |
| Potentiometer | Place ohm meter test leads on the blue and green | |
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| pot. leads. Reading should be 1 K ohms. | |
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| Place meter leads across the blue and purple pot. | |
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| leads and rotate knob from high to low. Repeat on | |
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| green and purple leads. Check for even rise and | |
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| fall of ohms reading to insure that there are no open | |
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| or dead spots in the potentiometer. Check each | |
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| lead to ground for shorts. Replace pot if it does not | |
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| meet the above test. | |
| Mercury Contactor | Check for supply voltage to the contactor coil. If | |
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| voltage is present and the contactor will not | |
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| activate, replace the contactor. Also, check each | |
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| contactor for proper high voltage input and output. | |
| Heater Elements | Check the amp draw on each hot leg for proper | |
|
| load. Check the specifications plate for rating | |
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| information. If the amp draw is low or high, check | |
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| the individual elements for opens, shorts, and | |
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| proper resistance. WITH POWER OFF: To check | |
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| resistance of the elements, remove all leads from | |
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| the elements and use an accurate digital VOM. | |
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| The element resistance should be as follows: | |
|
| 208V - 27 ohms | approximately |
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| 240V - 36 ohms | approximately |
Oven heats with switch off | Mercury Contactor | The mercury contactor has probably malfunctioned | |
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| in the closed position. If there is no voltage to the | |
|
| operating coil, but there is high voltage at the | |
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| contactor out put, replace the mercury contactor. | |
Intermittent Heating | Thermal/Overload of motor | The main fan motor is equipped with internal | |
|
| thermal protection and will cease to operate if | |
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| overheating occurs. As the motor overheats and | |
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| then cools, this will cause the oven to cycle on and | |
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| off intermittently. This may be caused by improper | |
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| ventilation or preventive maintenance. Also, most | |
|
| of the problems listed under "Oven will not heat" | |
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| can cause intermittent failure. | |
Conveyor will not run | Voltage Supply | Check incoming voltage supply at line 1 to neutral. | |
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| There should be a voltage reading of 208/240 VAC. | |
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| If not present, check breakers. | |
| 10 Amp Fuse | Check and/or replace. | |
| Fuseholder | Check and/or replace. | |
| Fan Switch | See procedure for checking on page 8. |
14 | Impinger II – Advantage Service Manual - Domestic |