Potentiometer Removal And Replacement - Thermador Pro Grand PRD304EG Service Manual

Service Manual for Thermador Pro Grand Dual Fuel Ranges:
4.5.7

Potentiometer Removal and Replacement

Be sure to check QuickFinder for relevant information, documentation,
and the correct part number when replacing this component.
The potentiometer (also known as the simmer control potentiometer
or XLO potentiometer) is used to control the simmer function of the
XLO burners. The potentiometer should not be confused with the
temperature selector switch, which is sometimes also referred to as a
potentiometer.
Figure 87: Typical Potentiometers
This procedure is for removing and replacing the potentiometer when
accessed from the top of the range (under the maintop). The
potentiometer can also be removed and replaced easily through the
front of the range (after the front panel has been removed), however
front panel removal also requires access from the top of the range.
NOTE: If the control panel has already been removed per
Control Panel and Bullnose Removal and Replacement procedure on
page 64, you can easily remove the potentiometer by detaching the
plastic wire connector at the potentiometer and then pulling the
potentiometer off of the XLO valve (it should snap off). If the
potentiometer to be replaced is located behind the manifold support
bracket, first remove and retain the screws on the bracket, and then
remove the bracket before pulling the potentiometer off (see
Figure 90, page 49).
1. Follow all safety precautions and steps in Preparing the Range for
Servicing, page 21.
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PRD304EG, PRD364EDG, PRD364EDPG, PRD364ELG, PRD366EG, PRD366EPG, PRD484ECG, PRD484EEG, PRD486EDG, PRD486EDPG, PRD486ELG
2. Follow all steps in Accessing Components under the Maintop,
page 21.
3. Remove knob from valve stem by slowly pulling knob straight out,
away from control panel.
4. If obstructing access to the potentiometer—XLO valve—solenoid
assembly, remove the burner support rail (with jet holder
assemblies attached) by following the steps in Removing the
Burner Support Rail, page 24.
5. Use a 1/2 inch wrench to hold the nut on the solenoid valve, while
unscrewing the gas tube hex nut with a 9/16th inch wrench. Then
unscrew the other side of the gas tube attached to the jet holder
assembly and remove the gas tube. Be careful not to bend the
gas tube (see Figure 80).
6. First make a note of how the wires are connected to the solenoid
valve terminals, and then remove the wires from the terminals.
NOTE: It is always recommended to label and tag all wires, wire
connectors and harnesses prior to disconnecting them, so as to
correctly identify their connections/locations when re-assembling.
Alternatively, you can photograph the wire connections prior to
disconnecting (for example, with your mobile phone).
7. Use an adjustable wrench to unscrew the large hex nut on the
solenoid and remove the solenoid valve from the XLO valve. Be
careful not to lose the plastic O ring positioned inside the large
hex nut of the solenoid valve, as it may fall out easily
(see Figure 79).
8. Use a 1/4 inch nut driver or a 1/4 inch socket wrench/ratchet to
remove and retain the valve screw by accessing it from under the
chassis base, through the corresponding access hole. The oven
door must be opened or removed (see Figure 75 and Figure 76).
Be careful not to lose the rubber washer attached to the screw.
9. Gently lift the protruding part of the XLO valve out of the
receptacle on the manifold (don't lose the red rubber washer
attached to the XLO valve), and slightly bring out the (connected)
XLO valve/potentiometer assembly from under the front panel. Be
aware of the side connector that is attached.
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