Go to Electronics 838 and 8310
Before attempting any repairs, check out the electrical safety page.
The eyebrow of the 838 and 8310 (after the last recall) simply consists of switches and 12 volt lights. Earlier versions (not covered) had 120 volt passing through a switch and the AC light. The eyebrow receives 12 volt from the power supply and returns various 12 volt signals to the power supply via the J1 plug, depending on the setting of the switches. The graphic below depicts a three way model. The two way version has only one switch and is much simpler. The input and output at the J1 plug is the same for both two way and three way models, where applicable (120 volt and gas).
For better understanding, the switch labels (AC OFF DC/GAS) in the graphic below are backwards compared to the actual labels on the eyebrow. This is because the switches pivot in the middle and the actual connections at the rear of the switch are opposite of the labeling.
Instead of verbally going through each combination of switch positions, it's more practical to just follow the diagram for the various positions, keeping a few things in mind. The lower half of the switches control the indicator lights on the eyebrow; the top half of the switches send 12 volt(+) to the power supply at the appropriate connections of the J1 plug (depending on what is selected). Power to the eyebrow comes from the black wire (J1-1) and the yellow wire (J1-8). The wire positions of the J1 plug are numbered from the bottom up. The yellow wire supplies constant voltage for the indicator lights, while the black wire passes through the thermostat and supplies the voltage for the actual switch selections to the power supply board (only when the thermostat is closed). The two position switch is dependent upon the three position switch for power. In other words, the two position switch only has power to it when the three position switch is set to DC/GAS.
Troubleshooting. Troubleshooting the eyebrow is best begun at the J1 plug with a 12 volt test light or meter. Be careful, there is 120 volt present at certain points of the power supply board, but not at the J1 plug if the last recall was done. If the last recall has not been done, the diagram above does not apply and there will be 120 volt at the J1 plug. After making the desired switch selections at the eyebrow, test for power at the appropriate connections of the J1 plug using the table below. If power is not present at the connection it should be, trace the problem back to the eyebrow using the diagram above. Remember, the eyebrow gets its power from the black wire (J1-1) and the yellow wire (J1-8) and needs that before any lights or output are possible. Also, don't overlook the fact that the power from the black wire (J1-1) passes through the thermostat.
|Violet (J1-12)||12 volt(+) when DC selected on three way models|
|Tan (J1-11)||12 volt(+) when Gas selected|
|Gray (J1-10)||Ground (-) for Gas and DC lights|
|Red (J1-9)||To eyebrow Check light|
|Yellow (J1-8)||12 volt (+) for eyebrow lights|
|White (J1-5)||Ground for (-) AC light|
|Orange (J1-4)||12 volt(+) when AC selected|
|Black (J1-1)||12 volt(+) to thermostat and eventually to eyebrow switches for heat selection|
You can find the actual wiring diagrams in the Library.