Assembling the Peak and Hold Injector Driver Board


Peak and Hold Injector Driver Board layout

The above diagram can be a useful guide to locate components as you assemble.

As a general rule, you’ll be installing the shortest components first, then the next tallest, on up to the tallest components on the board. This way you can install the components, flip the PCB over on a flat surface which will hold all of the components in place, and solder them in. Then install the next taller set of components and repeat until the board is finished. Note that there are are few components where orientation is important, and this is noted below. The resistors and smaller capacitors do not have a “backwards” or “forwards” so this is not as important for them.

  1.  First, install the smaller resistors: R1, R3, R5, R7, R9, R10, R12, R14, R16, R18, and R19 through R34.
  2. Next, install the small diodes: D1, D6, D11, D12, and D13. These have a banded end, either a silver stripe if they have a black body, or a black stripe if they have a red body. The banded end needs to be pointing to the same hole that the banded end on the silk screened rectangle points to.
  3.  Install the LM1949 driver chips, U1 through U8. These have a semicircular notch at one end. This notch needs to line up with the matching notch on the silk screen.
  4.  Install the smaller capacitors: C1 through C17, C20, and C21 through C28. Note that the labels for C21 through C28 fall inside the rectangles for the large resistors in the peak and hold circuits.
  5. Install the transistors Q11 through Q18. These transistors have a flat side that lines up with the flat side in the silk screen outline. Be careful as these have the most closely spaced legs of any components in the kit.
  6. Install the large resistors R2, R4, R6, R8, R11, R13, R15, and R17.
  7.  Install the large diodes D2 through D5 and D7 through D10. As with the diodes in step 2, the banded end needs to match the banded mark on the silk screened rectangle.
  8.  Install capacitors C18 and C19. These are polarized and the positive lead must go in the hole marked with the + sign.
  9.  Install the U9 voltage regulator and the large transistors Q1 through Q10. These must be soldered in place in such a way that the “shoulders” of their legs are even with the top of the PCB, and the flat side faces the outside of the PCB as they will be bolted to the case wall.
  10. Solder in the wires so they are coming out the top of the PCB. The five black wires go to the five ground holes – four of them are marked Injector Grounds and one is labeled GND. The red wire goes to the hole marked 12V. There are two sets of white wires. The first set white wires go go the injector inputs – these are put on the board in two rows of four, with 1 through 4 on the top half of the board and 5 through 8 at the bottom. The wires are marked with letters while the holes are marked in numbers, so the wire marked Injector A goes to IN1, the wire marked Injector B to IN2, etc. The second set of wires goes to the “INJ” holes located next to the injector drive transistors, and follow the same convention.
  11. Clean the board with acetone or rubbing alcohol before installing it in the case.
  12. First, use the heat sink compound to hold the eleven mica insulators to the wall of the case, with the hole in the insulator lined up with the hole in the case wall. Place a dab of heat sink compound on the insulators. Attach the board to the bottom of the case using the three bolts and spacers provided. Using a lock washer on the PCB will prevent it from vibrating loose. Use the insulated washers in the mica insulator kits along with the provided bolts, nuts, and lock washers to bolt the large transistors and U9 voltage regulator to the sides of the case. The insulated washers go on the inside, to keep the screw clear of the metal tabs on the transistors and voltage regulator. We recommend putting in the bolts so the screw heads are on the outside of the case.
  13.  Install the rubber grommets in the two holes in the side of the case.
  14. Run the wires out through the grommets. You’ll want to run the white wires connected to the inputs (IN1 through IN8) to one bundle, and cover with the heat shrink labeled INPUTS (from ECU). The white wires to the outputs (INJ1 through INJ2) need to be bundled up with the heat shrink labeled OUTPUTS (to injectors). The heat shrink tubing can be shrunk with a heat gun or cigarette lighter. The red and black wires may be run out either grommet, but we do not recommend bundling them in the heat shrink tube.
  15.  Install the case lid, and you’re done.

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