TM 5-6640-212-14
Table 5-2. Pyrometer Troubleshooting - Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
3. RED PILOT LIGHT ON AT ALL TIMES. - Continued
Step 3.
Check photocell.
If defective replace with new one.
4. INSTRUMENT PILOT LIGHTS OPERATE NORMALLY, BUT FURNACE OVERHEATS, OR WILL NOT HEAT.
Step 1.
Check wiring and connections from HCL terminals on terminal
panel to external contactor or other load.
Make necessary repairs.
Step 2.
Check operation of external contactors, solenoids, or motor valves.
Make necessary repair or replacement.
Step 3.
Check instrument relay contacts.
Clean dirty contacts, or replace relay.
5. INSTRUMENT NOT READING CORRECT TEMPERATURE.
Step 1.
Check thermocouple and lead wire connections.
Make necessary repair or replacement.
Step 2.
Check ambient temperature setting.
Make required adjustments.
Step 3.
Check thermocouple for deterioration and lead wire for correct polarity.
Make necessary repair or replacement.
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