Lincoln Impinger Conveyor Ovens 1100 Series - Manual (Page 32)

changing a board or tach. This test is not always
100% accurate as this test is not performed at
operating speeds. However, this test is the best
method currently available. Readjustment should
always be attempted at least once before replace-
ment. See procedure for board adjustment in
Section D.
DC Gearmotor If the problem seems to be the motor or gearbox.
Check the brushes in the motor for excessive
arcing and/or unusual wear. Check the motor
and gearbox from instructions located under
“possible cause” listing “Conveyor gear motor”.
Time/Temp Display 12.6 VAC Power Measure the transformer primary
inoperative Supply for a nominal 120 VAC input.
If 120 VAC primary voltage is not available, refer
to the schematic and trace the circuit for incomi
ng power failure
S/N 2011821 & Above Measure the secondary voltage
Refer to Page 45 output which will be 12.5 to 15
VAC normally. Recheck secondary
output at rear of Time/Temp
Display. Terminals 1 to 3 should
read 12.5 to 15 VAC. Terminals
1 to 2 and 2 to 3 should be
1/2 of the reading across 1 to 3.
If you do not get the above
secondary readings, replace the
transformer. The older units have a 4 amp
ambient fuse in each red secondary lead.
These may be jumpered to determine if they
are burnt out or intermittent.
Temp Display out or NOTE: Time/Temp displays Insert the thermocouple of your
erratic uses two types of temperature pyrometer into a finger hole in the top
sensor, Thermistor Probe - center of the oven. The thermocouple
2 yellow wires, Thermo- tip should measure air temperature
couple Probe - 1 red wire and must not be touching metal.
and 1 white wire Disconnect the yellow tipped thermistor
leads from the time/temp. terminals 9 &10
Thermistor Probe Measure the resistance of the thermistor
probe See the chart in Section D for proper
resistance readings.
Inspect the thermistor
bulb for itsproper location in its spring
holder.Check for short in leads where they
enter the sensor bulb. Also check each
thermistor lead for short toground.
Thermocouple Probe Connect temperature meter to
thermocouple at terminals 9 and 10 on back
of the time/temp display. (Be sure tomaintain
proper polarity on therocouple connections.)
Compare actual oventemperature with the
reading at the time/temp display. If the
temperature readings match, re-calibrate or
replace time/temp
Impinger II - 1100 Series Service Manual - International 32