DIYPNP Bosch 55 Pin Adapter Board Assembly
The Bosch 55 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
(+/-).
-
Install all four resistors R1A through
R4A in their respective slots.
-
(+/-) Install
D1A and D2A, making sure to point the banded end to the
right.
-
Install Q3A.
-
Apply heat sink compound to the silver
patch under Q2A. Bolt Q2A into place with a 4-40 screw and
solder to the PCB.
-
Bolt the 55 pin Motronic connector to
the board with the M4 screws and solder into place.
-
Slip the end plate notch into position
and put the end plate over the 55 pin connector.
-
Now for the tricky part - installing
Q1A. This one needs both a mica insulator and heat sink
compound. Q1A slips into the holes on the PCB and then bolts
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.
-
The IN jumper connects to the IAC
output on the main board.
-
The OPEN jumper connects to the opening
coil wire on the 55 pin connector.
-
The CLOSE jumper connects to the
closing coil wire on the 55 pin connector.
-
The 12V jumper connects to a 12 volt
source on the main board.
-
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.
|
