Appendix A Service Bulletin 0074
– NCC Electronic Temperature Control
http://www.gmpopcorn.com
Page 37
Trouble Shooting for Service Personnel
1.
If the kettle does not heat and there are no beeper sounds, look on the heat control to see if the green
PWR LED is on. The PWR LED indicates there is power to the control board. If the LED is not on, check
the Heat Switch and wiring. Check for 120 VAC (230 VAC) across terminals L1 & L2.
2.
If the kettle does not heat and/or the beeper sounds continuously check to be sure there is a set point
jumper in one of the 6 locations. Remove the jumper and clean the pins off, sometimes the conformal
coatings gets on the pins and acts as an insulator.
3.
If the kettle does not heat and/or the beeper sounds continuously, look on the heat control to see if
the red Probe LED is on. The Probe LED indicates there is a thermocouple problem.
a.
If the Probe LED is on and the Limit & Heat LED’s are off and the beeper is on there is a
problem with the Heat Thermocouple, TC-B wiring. Look at the terminal blocks for a loose
connection. Check the kettle wiring for a loose or broken thermocouple wire.
b.
If the Probe and Heat LED’s are on and the beeper is off there is a problem with the Limit
thermocouple, TC-A wiring. Look at the terminal blocks for a loose connection. Check the kettle
wiring for a loose or broken thermocouple wire.
c.
If the Probe LED is not on the thermocouple connections are OK. If the Limit LED and Alarm
LED’s are on and the beeper is on check the Set Point Jumpers. Most likely the jumper has
come off. If the Jumper is in place temporarily move it to a different temperature setting to see
if the control then works.
4.
If the kettle heats for a short time and then stops.
a.
If the Probe, Heat and Alarm LED’s are on and the beeper is on the Heat Thermocouple, TC-B is
wired reverse. Check for reversed thermocouple leads, see note 2 below. If the thermocouple
leads are reversed the kettle will heat up to about 240
F and stop with the Probe LED on. The
leads could be reversed at either the heat control itself or the terminal block.
b.
If the Probe and Heat LED’s are on and the beeper is off the Limit Thermocouple, TC-A is wired
reverse, troubleshoot as in item 3-a above. Note this is similar to 2-b above, the difference is
the kettle started to heat and then quit.
5.
The kettle is popping normally but the beeper does not sound, check for a missing jumper
at J4.
6.
Salt or Sweet temperature is not working correctly. Check to make sure both temperature set point
jumpers are in place and wired correctly. Be sure the common wire for the switch or relay is
connected to a bottom pin of one of the set point jumpers.
