Step 5: Install the Main Board’s Logic

R1 1K 5W
R2 1K (brown black red)
R3 10K (brown black orange)
R4 3.3Ω (orange orange gold gold)
R5, R6 100K 1/2W (brown black yellow)
C1–C6 1uF
C7–C9 100uF
C10 680uF
D1, D2 1N4148
D3 Low power rectifier
IC1 74HCT14
IC2 74HCT74
IC3, IC4     UCC37321
IC5 7815
IC6 7805
T1 Gate Drive Transformer
T2 Line Transformer
FB1 Optic fiber receiver
J_AC Clover connector


  • A. Install R1. Note that is a large, rectangular, ceramic, 5-Watt power resistor.
  5 watt bleeder resistor


  • B. Install R2–R6. ENSURE THAT R5 AND R6 ARE INSTALLED PROPERLY. They are two 1/2W bleeder resistors which drain the bus capacitors when the unit is powered off. Failure to install R5 and R6 properly will result in the capacitors storing energy for extended periods of time, and a board that is unsafe to service.
    Install the bleeder resistors


  • C. Install capacitors C1–C6. They are all identical 1uF ceramic capacitors.
  • D. Install capacitors C7–C10. These are electrolytic capacitors whose polarity is important. Be sure to match the white stripe on the capacitor to the stripe on the board.
  • E. Install signal diodes D1 and D2. Note that these are directional components, and the stripe on the diode needs to match the stripe on the board.
  • F. Install rectifier D3. Note that it is directional.
  • G. Install the sockets for IC1–IC4. You will insert the ICs into the sockets later. Note that the sockets are directional, and the notch on the socket needs to match the notch on the board.
    Match the socket to the board


  • H. Install voltage regulators IC5 and IC6. The orientation of the component should match the silkscreen on the board.
  • I. Install T1 and T2, the gate drive transformer and the line transformer.
  • J. Install FB1, the fiber receiver. Be careful! This component is delicate. Soldering this component at too high a temperature can damage it. We recommend soldering at no higher than 400°C. Secure it to the board with a bolt and nut before soldering the leads.
  Fiber optic receiver


  • K. Insert the ICs into their sockets. Ensure that the notch on each IC matches the notch on the socket, and double-check that the notch on the socket matches the notch on the board.
  • L. Install J_AC, the power connector. Put a dab of glue under the part to hold it firmly in place.



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