|
| LEADS ATTACHED TO THE TEMPERATURE | ||
|
| CONTROL BOARD: measure D. C. millivolt output of | ||
|
| these leads. Refer to thermocouple chart in SectionD | ||
|
| for proper readings. If these readings | ||
|
| are not achieved, replace thermocouple. | ||
| Temperature Control | WITH POWER OFF: remove the | ||
| Potentiometer | potentiometer leads from the temperature control | ||
|
| board and measure ohms from black to white leads. | ||
|
| The reading should be from approximately | ||
|
| 0 to 2.5k ohms as the dial of the | ||
|
| potentiometer is turned throughout its full rotation. | ||
|
| From black to red leads, the reading should be | ||
|
| approximately 2.5k ohms (constant) throughout the | ||
|
| full rotation of the dial. If these readings are not | ||
|
| achieved, replace potentiometer. If the thermocouple | ||
|
| probe and the control potentiometer check good, | ||
|
| then the problem is usually with the temperature | ||
|
| control board. |
| |
| Mercury Contactor | Check for 120 VAC to the contactor coil. If voltage is | ||
|
| present and contactor will not activate, replace the | ||
|
| contactor. Also, check each 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 | ||
|
| information.If the Amp. draw is low or high, check | ||
|
| the individual elements for opens, shorts, and proper | ||
|
| resistance. |
| |
|
| WITH POWER OFF: To check resistance of the | ||
|
| elements, remove all leads from the elements and | ||
|
| use an accurate digital VOM. The element resistance | ||
|
| should be as follows: | ||
|
| 220V - | 30 ohms | approximately |
|
| 240V - | 36 ohms | approximately |
Oven heats with switch off | Mercury Contactor | The mercury contactor has probably | ||
|
| malfunctioned in the closed position. | ||
|
| If there is no voltage to the operating | ||
|
| coil, but there is high voltage at the | ||
|
| contactor output, replace the mercury | ||
|
| contactor. |
| |
Intermittent Heating | Thermal/Overload | The main fan is equipped with internal | ||
|
| of motort hermal protection and will cease to | ||
|
| operate if overheating occurs. If the | ||
|
| motor overheats and then cools, this will | ||
|
| cause the unit to cycle on and off | ||
|
| intermittently. This may be caused by | ||
|
| improper ventilation or preventative | ||
|
| maintenance. Also, most of the problems | ||
|
| listed under “Oven will not heat” can | ||
|
| cause intermittent failure. | ||
Impinger II - 1100 Series Service Manual - International | 39 |
