| Temperature Control Board | Check for 120 VAC input to temperature control |
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| board. If not present, check wiring from fuse holder |
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| to temperature control board. Turn the temperature |
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| adjustment dial to the maximum temperature |
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| position Check for 120 VAC at coil of mercury |
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| contactor(s). Next, short the leads of thermocouple |
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| on the temperature control board, check for 120 |
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| VAC at coil of mercury contactor(s). If voltage is not |
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| present, replace temperature control board. If |
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| voltage is present proceed. |
| Temperature Control | Potentiometer is 0 to 2.5K ohm. WITH POWER |
| Potentiometer | OFF: remove the leads from the temperature |
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| control board terminals 1, 2, and 3 and measure |
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| ohms from black to white leads. The ohm reading |
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| should be 0 to approximately 2.5K ohms as the dial |
| Thermocouple Probe | Remove thermocouple leads from the temperature |
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| control board, and measure the millivolt output of |
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| the leads. Refer to chart in adjustment section for |
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| proper millivolt readings. |
| Mercury Contactor(s) | Check for 120 VAC to the contactor coil. If voltage |
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| is present and contactor will not activate, replace |
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| the contactor(s). Also check each contactor for |
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| proper high voltage input and output. |
| 50 Amp Fuses | If there is no high voltage input to the mercury |
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| contactor(s), check the 50 amp fuses and replace if |
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| necessary. |
| Heater Elements | Check the Amp. draw on each hot leg for proper |
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| 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 . To check resistance of the |
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| elements, turn off the power! Remove all leads |
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| from the elements and use an accurate digital |
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| VOM. The element resistance should be as follows: |
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| 208V - 9.8 ohms approx. 220V - 10.5 ohms approx. |
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| 240V - 13 ohms approx. If all readings are not |
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| correct, replace elements as needed. |
Oven heats with switch | Mercury Contactor(s) | The mercury contactor has probably malfunctioned |
off |
| in the closed position. If there is no voltage to the |
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| operating coil, but there is high voltage at the |
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| contactor output, replace the mercury contactor. |
Conveyor will not run | Voltage Supply | Check incoming voltage supply at line 1 to neutral. |
(S/N |
| There should be a voltage reading of 120 VAC. If |
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| not present, check breakers. |
| 3 Amp Fuse | This conveyor fuse is located on the front panel. |
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| Replace if defective. |
| Fuse Holder | Check and/or Replace. |
| Conveyor Switch | Same procedure as for fan switch. |
| D. C. Motor Control Board | Check for 120 VAC input to D. C. control board |
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| across L1 and L2. Check the 3 amp fuse on the D. |
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| C. control board. Check for D. C. voltage at |
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| terminal F1 and F2. Voltage should be 10 VDC + |
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| 10 steady. If this voltage is not present, replace D. |
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| C. control board. Check for D. C. voltage output to |
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| the motor across terminals A1 and A2 (this voltage |
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| should be approx. 125 VDC at maximum conveyor |
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| motor speed). |
40 | Impinger I |
