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| under “Oven will not heat” can cause |
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| intermittent failure. |
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Conveyor will not run | Power supply | Check incoming power supply, If no voltage is | |
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| present, check circuit breakers. |
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| Fan switch | With power off, Check continuity between |
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| switch terminals. Replace as needed. |
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| Speed adjustment | This is a 0 to 10K ohm, 1 turn potentiometer. |
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| potentiometer | With power off, remove the black and white |
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| pot. leads from the motor control board at |
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| terminals P1 and P2. Place the meter leads on | |
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| the black and white pot. leads. Rotating the |
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| pot. slowly, from low to high, the meter reading | |
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| should show an even transition from 0 to 10K | |
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| ohms ± 5%. There should be no dead or open | |
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| spots throughout the rotation of the |
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| potentiometer. Check both pot. leads to |
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| ground. There should be no continuity to |
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| ground. If any of the above checks fail, replace | |
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| the potentiometer. |
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| DC motor control board | Check for supply voltage input to the control |
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| board at terminals L1 and L2. If voltage is not | |
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| present, check wiring back to the oven fan |
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| switch. If supply voltage is present, check both | |
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| fuses on control board (8A line and 1A |
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| armature). Check the DC voltage output at |
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| terminals A+ and | |
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| control board but no power at A+ and | |
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| the following: |
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| Hall effect sensor | Disconnect the Hall effect sensor from the DC | |
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| motor control board. If the motor begins to run, | |
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| replace the Hall effect sensor. |
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| DC motor control board | If, after disconnecting the Hall effect sensor, |
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| the motor is still not running, check for DC |
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| voltage from terminals A+ and | |
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| DC voltage, replace the DC motor control |
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| board. |
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| Circuit breaker | If there is DC voltage output from the DC motor | |
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| control board, but the motor is still not running, | |
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| check the 0.4 Amp circuit breaker. Disconnect | |
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| wires from the circuit breaker and check for |
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| continuity through the circuit breaker. Reset |
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| circuit breaker or replace as needed. |
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| Conveyor gearmotor | Check the leads to the motor for evidence of |
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| any shorts or opens, and each lead to ground. | |
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| If the motor fails the above tests, replace |
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| motor. Rotate motor shaft to determine if there | |
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| is a locked rotor or a locked gearbox (use care | |
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| so that magnet and sensor are not damaged). | |
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| Check motor brushes for damage or excessive | |
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| wear. Replace brushes if needed. Replace |
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| motor if needed. Also check to be sure that the | |
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| conveyor drive coupling is tight and properly |
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| engaged to the conveyor shaft. |
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| Conveyor | Check for any mechanical misalignment. Also, | |
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| check for worn bearings. A conveyor belt that is | |
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| too tight may cause excessive bearing wear |
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| and sometimes, irregular speed. |
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Conveyor speed unsteady | Power supply | Check power supply at the DC motor control |
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| board for supply voltage at terminals L1 and |
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| L2. Supply voltage should be steady. |
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Impinger II – | 13 |