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Notes for main pcb

Always follow ESD precautions when handling master PCBs.Although the main PCB can resist electrostatic discharge, there is still the possibility of damage to electronic components.Do not operate the main control panel without turning off the power of the machine.Although the input voltage to the PCB is only about 36V DC, processing the PCB while the PCB is still powered on can short-circuit components and severely damage the PCB.

main pcb
main pcb

The main control panel can only be replaced after other components have been excluded in the electrical troubleshooting step because of machine failure or obvious defects in the main control panel.Customer maintenance personnel can safely perform this process as long as necessary precautions are observed.Before replacing the motherboard, it is strongly recommended to discuss with the new MelBoa technical support, as other causes may cause machine failure, which may look like a motherboard failure, but may actually be electrical short circuit of harness, software damage, etc.

Replacement parts:

Thermal pads must always be installed on the four flat pad supports below the main PCB.If these components are removed or not installed, the master board will be short-circuited and the components will be burned out.There is no need to replace the spacer unless it is damaged or removed for some reason.

Replacement procedure:

  1. Turn off the machine.
  2. Let the machine sit in a position that does not touch the PCB, and then place your hand somewhere on the main body of the machine (not the main PCB) to disperse the residual static electricity on the machine or body.Warning!!When removing the bottom cover, be careful not to drop metal objects, tools or other conductive materials onto the motherboard.If such items fall onto the motherboard, the electronic equipment may be seriously damaged and the maintenance cost is very high.
  3. Remove the bottom cover from the machine.Warning!!Before installing the EMI cap, ensure that all harness underneath the cap is sufficiently relaxed to prevent clamping the harness or pulling the connector loose when installing the EMI cap.Do not press the EMI cover onto the harness.
  4. Unscrew the edge screw of the EMI cover to remove it.To remove the 33322 series EMI cover, see Remove EMI cover-33322 series.
  5. Disconnect all harness from the motherboard at once and place the connector close to the socket from which the connector is removed.
  6. Remove the M4 X 8mm flange hexagonal screw that mounts the main PCB to the base of the machine.
  7. Only remove the primary PCB from the motherboard from the edge (especially if it is sent to Melco Quality Assurance for fault analysis).
  8. Put the old main PCB in the anti-static protective bag.
  9. Remove the spare main PCB from the shipped anti-static protection bag, grab only its edges, and place it in the appropriate position on the base of the machine.
  10. Install the M4 X 8mm flanged inner hexagonal screw and tighten the screw to the minimum new Mel Torque Specification (only enough to secure the main PCB in place).
  11. Connect all harness to the corresponding socket on the motherboard at once.
  12. Carefully replace the EMI cover as provided in “EMI Cover-32232 Series” or “EMI Cover-32188 Series” (see Figures 2A and 2b for pictures), and then install the bottom cover.
  13. Turn on the machine.
  14. Perform machine function tests to verify that the motherboard is in good condition.
  15. Run the AMPASSXXX test design long enough to ensure that all electronic devices and motors are operating properly.You don’t have to run the entire design.It may be sufficient to run only the first two parts of AMPASSXXX (horizontal and vertical columns).



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