Quoted from debooen:
Hi...I'm not getting any reading on the CPU test points...does that mean issue is with the power supply board?
The Power Supply Board (PSB) has test points on it for +12VDC [Volts DC], -12VDC, +5VDC and a Ground. These are up at the top of the board to the right of the big silver heat sink and to the left of the yellow and white wire bundle coming off the board.
1) Turn on the machine and check here for +5VDC. The black lead from the multi-meter can go to the ground test point and the red one to the +5 test point.
If present, the +5VDC section of the PSB is probably ok.
If you do not get +5VDC, turn off the machine and remove connector CN6 (Power supply board to MPU board, bottom left hand side of the PSB), turn on and test again. If you get voltage now, something is using up all the voltage before the MPU board can use it. This could be the cable, corrosion or a failed component, but it means the problem is probably not the PSB.
+5VDC is fed to the DMD Display via CN5. The pins for this connector also carry higher voltages, be careful when the machine is turned on. Turn off the machine, remove the CN5 connector (next to CN6), turn on and test for +5VDC again.
If you get +5VDC after you disconnect CN6, the DMD parts of the machine may be sucking all the +5VDC out of the system. Not likely, but they need to be eliminated. You could reconnect CN5 to the MPU and check again to verify it is just the DMD.
If you don't get +5VDC, move to the +12VDC test point on the Power Supply Board and test there. CN5 and CN6 are probably not involved; you can reconnect them if you want. You can use the same test point for the ground side as you did with the prior test.
The Power Supply board makes 12VDC from the Bridge Rectifier, then uses 12VDC to make 5VDC. If there is no 12VDC, the board won't create any +5VDC either even if that part of the circuit is ok.
If you get +12VDC but not +5VDC it narrows it down to one area of the PSB, if you don't have +12VDC, it's another. This isn't a solution to your problem, but it'll get you closer to one. Post your results.
Added 45 days ago
Edit: I just reread this and have a typo in the DMD notes in one place. DMD connected to CN5, not CN6.
Should read "If you get +5VDC after you disconnect CN5, the DMD parts of the machine may be sucking all the +5VDC out of the system. ..."