Lincoln 1100 Series Service Manual page 26

Oven heats with switch
off
Intermittent Heating
Conveyor Will Not Run
S/N 2011383 and
above 1130 through
1133 – S/N 2011978
and above Models
1160 through 1163
Refer to Page 29
Conveyor speed
varying or intermittent
26
Mercury Contactor
Thermal/Overload of Motor
Conveyor Switch
3 Amp Fuse
Fuseholder
Speed Adjustment
Potentiometer
DC Motor Control Board
Conveyor Gear Motor
Conveyor
Power Supply
240V - 36 ohms approximately.
The mercury contactor has probably malfunctioned in
the closed position. If there is no voltage to the
operating coil, but there is high voltage at the
contactor output, replace the mercury contactor.
The main fan motor is equipped with internal thermal
protection and will cease to operate if overheating
occurs. As the motor overheats and then cools, this
will cause the units to cycle on and off intermittently.
This may be caused by improper ventilation or
preventative maintenance. Also, most of the problems
listed under "Oven will not heat" can cause intermittent
failure.
Check for continuity between switch terminals
Check, replace as needed
Check, replace as needed
This is a 0 to 5 K ohm, 10 turn potentiometer. WITH
POWER OFF: Remove the red, black and white pot
leads from the motor control board at terminals P1, P2
and P3. With a digital multimeter, check the ohm
reading across the red lead (P3) to the black lead
(P1). This reading should be 5 K ohms
pot is rotated from low to high. Place the meter leads
on the red lead (P3) and on the white lead (P2)
Rotating the pot. slowly, from low to high, the meter
reading should show an even transition from 0 to 5 K
ohms 5%. There should be no dead or open spots
through out the 10 turns of the pot. Check all three
leads to ground. There should be no continuity to
ground. If any of the above checks fail, replace the
pot.
Check for 120 VAC input to the control board at
terminals L1 and L2. If not present, check the
conveyor switch and wiring back to 3 amp fuse and
then back to power source if necessary. If 120 VAC is
present at L1 and L2, check the VDC output at
terminals A+ and A-. If a DC voltage is not present,
check the 4 amp and the 1 amp fuses on thecontrol
board. If 120 VAC is present at terminals L1 and L2,
but DC Voltage is not present at A+ and A-, providing
the fuses are good, replace the board. If DC voltage
is present at A+ and A-, but motor does not run, check
gear motor as follows.
If DC voltage is present at A+ and A-and the motor
does not run, first check the mini breaker and then the
conveyor. As described below under "conveyor."
WITH POWER OFF: Check the leads to the motor for
evidence of any shorts or opens, and each lead to
ground. Remove dust cover from the top of the motor
and rotate motor shaft to determine if there is a locked
rotor or a locked gear box (use care so encoder disc is
not damaged). If the motor fails the above tests,
replace motor.
Check for any mechanical misalignment or improper
adjustment. Also check for worn bearings. The
Installation and Operations Manual shows proper
conveyor belt position. A conveyor belt that is too tight
will contribute to excessive load, bearing wear, and
wearing of slider bed rods.
Check power supply at the DC control board for the
120 VAC at board terminals L1 and L2. If voltage is
not present and steady, check the main circuit
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