Brother International DCP 8040 Service Manual - Page 231

CHAPTER 6 TROUBLESHOOTING 6. TROUBLESHOOTING OF THE CONTROL PANEL L-1 Nothing is displayed on the LCD. User Check (1) Verify if the power switch is turned off. Possible cause Connection between main PCB, relay PCB, and control panel PCB Harness between main PCB, relay PCB, and control panel PCB Connection between main PCB and lowvoltage power supply PCB Harness between main PCB and lowvoltage power supply PCB LCD LCD Step 1 2 3 4 5 Control panel 6 PCB Relay PCB 7 Low-voltage 8 power supply PCB Main PCB 9 Check Main PCB and control panel PCB are properly connected. Harness wire is damaged. Main PCB and low-voltage power supply PCB are properly connected. Harness wire is damaged. Replacement of LCD solves the problem. Replacement of control panel PCB solves the problem. Replacement of relay PCB solves the problem. Replacement of low-voltage power supply PCB solves the problem. Replacement of main PCB solves the problem. Result Remedy No Fix the connector properly. Yes Replace the harness with a normal part. No Fix the connection properly. Yes Replace the harness with a normal part. Yes Replace the LCD with a normal part. Yes Replace the control panel PCB with a normal part. Yes Replace the relay PCB with a normal part. Yes Replace the low-voltage power supply PCB with a normal part. Yes Replace the main PCB with a normal part. 6-28