Lincoln 1100 Series Service Manual page 28

28
Thermocouple Probe
Erratic time/temp dispaly
Temp Display inaccurate,
erratic or inoperative
Time Display inaccurate,
erratic
Optical Encoder
Place your pyrometer thermocouple into the center of
top finger. Connect temperature meter to
thermocouple at terminals 9 & 10 on back of the
time/temp display. (Be sure to maintain proper
polarity on thermocouple connections.) Compare
actual oven temperature with the reading at the
time/temp display. If the temperature readings match,
re-calibrate or replace time/temp display. If the
readings do not match, replace thermocouple probe.
If strange or unusual behavior is experienced such as
a rolling of numbers, or lock up at a given number, first
check for a display circuit lock up. This can be caused
by a voltage spike or surge in the incoming power
lines. To eliminate this condition remove power from
the time/temp. display by shutting off the main fan
switch for 15 seconds, or if display stays on, (older
models) circuit breaker interruption may be required.
This should eliminate the problem. If the problem
continues, jumper the two fuses in the red wires
leading from the 12.6 VAC transformer to the display
on older units. If this does not solve the problem, it
may be coming in through the commercial power lines.
Suggest that customer contact his power company for
evaluation.
Perform the power supply check, the thermistor probe
check, and then perform the time/temp simulator test.
Refer to Removal, Installation, and Adjustment section
for instructions (see page 42). Remember, when using
the time/temp simulator, remove all the leads from the
back of the display except the 3 power leads. After
completion of this test and if reinstalling display back
into the oven, the dip switches must be reset for oven
operation.
Perform all checks as in the above evaluation. If the
time check is okay, or inoperative refer to the next
section, optical encoder.
The above time/temp test should have already been
performed. Remove dust cover from the gear motor
and inspect the coupling and encoder disc. The
coupling set screws should be tight and not slipping on
the motor shaft or the tach. generator shaft. The
encoder disc should be firmly attached to the coupling
and not warped. Check the positioning of the optical
encoder disc. The disc should not be touching the
optical encoder assembly and the encoder assembly
should be mounted so it is squarely facing the
coupling shaft. This is to allow the infrared light
beams to be broken by the encoder disc. If all this is
okay, then replace the optical encoder assembly.
Impinger II –1100 Series Service Manual - Domestic