Thermo Scientific Thermolyne NCAT F85930, Инструкция по установке и эксплуатации

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15
Preventive Maintenance and Servicing
To Replace a Type K Filter Thermocouple
Thermo Scientific NCAT Asphalt Content Tester 69
10. Test operation of furnace.
To Replace a Type K Filter Thermocouple
1. Disconnect furnace from power supply. (See “Replacement Parts” on page 73 for normal cold
resistance value.)
2. Remove the back terminal cover of the furnace. (Note placement and connection of T/C lead
wires.)
3. Remove the screws on the filter thermocouple terminals and disconnect the filter thermocouple
wires.
4. Remove the clamp retaining the thermocouple.
5. Pull the thermocouple straight back.
6. Insert the new thermocouple into the case.
7. Replace the clamp securing the thermocouple.
8. Connect the leads to the terminal block, matching the wire colors with the incoming wires.
9. Replace the back terminal cover on the furnace.
10. Reconnect the furnace to the power supply.
11. Test the operation of the furnace.
To Replace a Solid State Relay
Three solid state relays are located inside the lower control section at the rear. The relays are mounted
on the heat sink inside the case. Facing the front of the furnace, the fan relay is on the right, chamber
elements relay middle and filter relay on the left. See
“Wiring Diagrams” on page 81 .
1. Disconnect furnace from power supply.
2. Remove the screws on the front dial plate. Open the front dial plate and remove the two hex 8/32''
(11/32'' socket or wrench is required) nuts in the lower corners behind the front dial plate.
Remove the eight screws on the lower back cover.
3. Remove the (3) four wire modular connectors, one on the right and two on the left, behind the
front cover. (The connectors have a locking tab which has to be opened before removal).
4. Remove the remaining (5) cables from the printer, balance, and display board.
The thermocouple circuit consists of the thermocouple and thermocouple extension
lead wires. Polarity plus to plus and minus to minus must be maintained in the
circuit. Reversing lead wire polarity, thermocouple lead wires touching one another
or grounding to case will cause the chamber temperature to exceed the setpoint
temperature and could cause element failure. The actual displayed temperature will
read on the low side of setpoint temperature.