Troubleshooter - Maxitrol

1e Thermocouple

Check the thermocouple

Measure the thermocouple voltage in mV just after the servomotor starts to run and the voltage goes down. 
Measure between the red dot on the receiver and the earth point on the gas control. 
Based on the results follow the steps below. 

• 0 mV
• 2-3 mV
• 3-5 mV
• > 6 mV

Voltage 0 Mv:
- The thermocouple is defective. Check by replacing or measuring the voltage at the end whilst heating the tip with a lighter
- Short circuiting or interruptions could be present in the circuit. Check:
          - The thermocouple is tight in the interruptor
          - The interruptor is tight in the gas control
          - Black wires (With a yellow/red end) are connected to the interruptor and receiver
          - Interruptor (Mount thermocouple directly in the gas control and ignite in Manual Mode, follow these instructions.) If the pilot stays on the interruptor is defective.  

Voltage 2-3 mV

Check the pilot flame. If it's too small:

• The pilot is dirty. Follow these instructions. 
• Check for the pilot gas tube tightness
• Check to see if the pilot tube is kinked or has dirt inside
• Check if the line pressure is too low

Voltage 3-5 mV

The appliance might work but is too critical. 
Perform the actions as described above for voltage 2-3 mV. 

Voltage 6 mV

The voltage is okay, so there is a different cause.

- The receiver is defective. Check by dismounting the black-red and yellow control cables from the receiver and link them together. Ignire fire in Manual Mode. If the pilot stays on: The receiver is defective. 

- If the receiver is not defective, the gas control is. Replace the gas control.