DIYPNP JECS 93 Pin Adapter Board Assembly

The JECS 93 Pin Adapter Board has some extra circuitry for 3 wire IAC control. Here’s how to assemble it. As with the main board assembly, if it’s important not to get a component backwards, we have marked the step with (+/-).

  1. Install all four resistors R1A through R4A in their respective slots.
  2. (+/-)  Install D1A and D2A, making sure to point the banded end to the right.
  3. Install Q3A.
  4. Bolt the 93 pin connector to the board with the included screws and solder into place.
  5. Install the adapter board in the lower half of the case, and bolt the endplate into place. The adapter board needs to be flush with the endplate
  6. Now for the tricky part – installing Q1A and Q2A. These need both a mica insulator and heat sink compound. These transistor slip into the holes on the PCB and then bolt to the end plate with a 4-40 screw. Then solder it into place.

The 3 wire IAC circuit has five jumpers on a header on the far left of the adapter board. Here is how to connect these jumpers.

  1. The IN jumper connects to the IAC output on the main board.
  2. The OPEN jumper connects to the opening coil wire on the 55 pin connector.
  3. The CLOSE jumper connects to the closing coil wire on the 55 pin connector.
  4. The 12V jumper connects to a 12 volt source on the main board.
  5. The GND circuit connects to any GND jumper on the main board. You must have either the GND jumper in the 5 pin header or at least one of the GND pins in the 2 pin header to the right of the connector grounded for the IAC circuit to function.

Note that you do not need to add any flyback diodes on the main board if using the 3 wire IAC control circuit. It has flyback protection built in.