Main Circuit Board (second generation)
Before working with electricity, visit the Electrical Safety page.
The main circuit board controls and activates all of the heat sources (AC, DC, and gas) of the refrigerator. It requires 12 volt power at all times for the refrigerator to work on any heat source. The main circuit board takes its settings from the eyebrow board via a communication link and proceeds accordingly. It has the job of determining if AC is present, for example, and switching to gas if it's not. It directly controls the components of the gas system, and sends voltage directly to the 12 volt element and 120 volt element. The board shown below is a 3 way model. The 2 way version would not have terminal J1 and the 35 amp fuse.
Terminal Connections
| J1 | 12 Volt Element (for 3 way models) |
| J2 | Interior Light |
| J3 | Thermocouple |
| J4 | 12 Volt Positive (+) |
| J5 | AC In |
| J6 | AC In |
| J7 | AC Out (120 Volt Element) |
| J8 | AC Out (120 Volt Element) |
| J10 | Thermocouple |
|
| P1 | Eyebrow (detail below) |
| P2 | Thermistor |
| P3 | Gas Valve & Igniter (detail below) |
| 3 Amp Fuse | Board Circuitry (12 Volt) |
| 35 Amp Fuse | 12 Volt DC Heat Element (for 3 way models) |
| 5 Amp Fuse | 120 Volt AC Element |
|
Plugs P1 and P3 wiring:
 |
| Pin Number | Wire Color | Reading |
| 1 | Green | 12 volt +, when eyebrow switch on |
| 2 | Open | Open | |
| 3 | Black | 12 volt +, when eyebrow switch on |
| 4 | Orange or White | 12 volt + |
| 5 | Red | 12 volt - |
| 6 | Brown | Communication link |
|
 |
| Pin Number | Wire Color | Reading | Destination |
| 1 | White | 12 volt - | Ground Terminal |
| 2 | Yellow | 12 + when gas heat is called for | Gas Solenoid & Igniter |
| 3 | Open | Open | Open |
| 4 | Blue | 12 + when gas heat is called for | Test Point |
The wiring for P3 is different in the old wiring |
Troubleshooting Basically, troubleshooting the main circuit board entails a knowledge of what should happen when and testing the input and output of the various connections on the board. See the various heat source sections (AC, DC, gas) for troubleshooting the individual heat sources. If you suspect a communication problem between the main board and the eyebrow board, you can check the voltages at plug P1. If you suspect a cable problem between the two, you can check for voltages at P1 and at the eyebrow. Twelve volt goes to the eyebrow from P1, pin 4 and returns through pins 1 and 3 in P1 when the eyebrow switch is depressed to the "On" position. Knowing this and making corresponding tests at the eyebrow would test the cable between them. There is no test for the brown wire (pin 6, communication link). However, from experience, the eyebrow boards seldom fail. In a toss up, go for the lower, main board.
We sell the aftermarket, Dinosaur brand P-711 as a replacement for the main circuit board on these models.
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