Lincoln Series 1200 Manuel D’Utilisation

Impinger I -–1000 Series Service Manual - International

Time/Temp Display

12.6 VAC Power Supply

Measure the transformer primary inoperative for a

nominal 120 VAC input. Measure the secondary

voltage 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 exactly 1/2 of the reading across 1 to 3. If you

do not get the above secondary readings, replace

the transformer. If 120 VAC primary voltage is not

available, refer to the schematic and trace circuit

for incoming power failure. There is a 4 amp fuse in

each red secondary lead. These may be jumpered

(for test only) to determine if they are defective or

intermittent.

NOTE:

(Dual Belt Ovens)

Dual belt ovens utilize a double pole double throw

switch, which allows either of the optical encoders

to be read from a single Time/Temp. Display.

Check switch and replace as needed.

NOTE: Time/Temp displays

use two types of temperature

sensor, Thermistor Probe – 2

yellow wires Thermocouple

Probe 1 red wire and 1 white

wire

Place your pyrometer thermocouple into the center

between fingers T2 and T3 in the oven. Disconnect

the yellow tipped thermistor leads from the

time/temp. terminals 9 and 10. Measure the

resistance of the thermistor probe. See chart on

page 72 for proper resistance readings.

Thermistor Probe

Inspect the thermistor bulb for its proper location in

its spring holder. Check for short in leads where

they enter the sensor bulb. Also check each

thermistor lead for short to ground.

Thermocouple Probe

Place your pyrometer thermocouple into the center

between fingers T2 and T3 in the oven. 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, recalibrate or replace

time/temp display. If the readings do not match,

replace thermocouple probe.

Erratic time/temp display

If strange or unusual behavior is experienced such

as a rolling of numbers, lock up at a given number,

first check for a display circuit lock up. This can be

caused by a voltage spike or surge. To eliminate

this condition remove power from the time/temp.

display by shutting off the main fan switch, 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. 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.

Temp Display out or

inaccurate

Temp Display inaccurate

erratic, or inoperative

Perform the power supply check, the thermistor

probe check, and then perform the time/temp

simulator test. Refer to page 72 for instructions.

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 back into the oven, the dip

switches must be reset for oven operation.