The heat sinks and condensers on the PSU AC drive board are live and labeled with warnings not to touch them.

PSU-A, PSU-B

PSU-C

AC Drive Board

  • A heat sink can retain a considerable electrical charge (100 to 400V) for up to several months after the machine has been turned off or the board has been removed and stored. Turning the machine off, disconnecting it from the power supply, and then allowing it to remain idle for a short time, allows the DC circuits to discharge. However, the AC circuits will retain residual charge.
  • To avoid electrical shocks, never touch any component on a PSU board or the AC drive board with bare hands or a tool, especially a heat sink or capacitor.
  • Always handle a board by its edges.
  • Always keep the rear covers on the machine.
  • Never leave the covers off during machine testing, or while the machine is idle during servicing.

  • Never touch the back of the board.
  • Some of the soldered contacts on the backs of the boards are extremely sharp and can cut or puncture your fingers, as well as cause an electric shock.