Thermo Scientific 3051 Series, Operating Manual And Parts List

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4. Remove the two nuts and shake-proof washers securing the heater
leads, then pull the lead terminals off the heater studs.
5. Remove the two screws securing heater to cabinet. Slide heater forward
to disengage back heater clips, lift back of heater up, then slide heater
back and lift out.
6. Install replacement heater and re-assemble oven by generally reversing
the steps above.
To replace a defective controller, proceed as follows:
1. Disconnect power cord from the electrical outlet.
2. Open the chamber door. Carefully remove and retain hardware from
door hinges (case side). Set door aside.
3. Slide the oven back until the front of the bezel (control panel) is at
least three inches from the edge of the bench top.
4. Prop up the oven front by placing a shim under each front foot. Use
shims between one and one-half and two inches in thickness.
5. Remove two screws securing bezel from bottom of oven.
6. Grasp bezel and pull bottom outward. Bezel will disengage from fascia.
Lay bezel on benchtop in front of oven.
7. Remove temperature dial knob.
8. Locate three push-on terminals at right hand side of controller board
(heater wire, two power wires). Disconnect the three lead wires by
pulling up and off terminals. Note connections for later re-assembly.
9. Remove four screws, which mount the controller board to the bezel.
Lift out board.
10. Loosen set screws in two-position terminal at front of controller board
and disconnect thermocouple wires. Thermocouples are polarity
sensitive so make a note of which terminal is red and which is yellow
for reassembly.
11. Install replacement controller by generally reversing the steps above.
Note When replacing the temperature dial, first rotate the dial shaft full
counterclockwise. Then replace knob with pointer at the 20° mark.
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Precision Standard Oven 6-5 Thermo Scientific
Section 6
Service
Replacing the Heater
(continued)
Replacing the
Controller