WCS94 won't start

[Josokas]

  New to pinball owning.
Bought a rough but working WCS94 pinball.
Was working fine for one day and now[size=78%] it won't start. Makes a loud ding sound when it's first turned on but nothing else. Every now and then the soccer ball spins too. But no lights, no DMD.[/size]
[/size]
[/size][size=78%]Picture of pcb boards when power one [/size][/size][size=78%]for ref.[/size]


Any tips/help greatly appreciated.

[robm]

By that picture, the machine is not booting properly. The top one of the 3 red leds on the mpu (the long narrow board on the left) should be off and the middle led flashing if it boots properly.

It could be  a bunch of things but i would start by unplugging and replugging the connectors j101 and j102 on the right hand side of the large power driver board on the right. These connectors can deteriorate over time and they supply the input power for the 5v and other voltages. If 5v is low, the machine will not boot.

Next step would be to reseat the game rom and push on the asic chip on the mpu

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[Josokas]

Thanks robm, but no luck.
Checked all voltages at test points and all within spec.


Checked all fuses all ok.


Any other tips?

[DSB]

What do the 3 x LEDs do on the CPU at switch on. Does the top LED just stay on or is there any flashing?

[Josokas]

The D19 and D21 LEDs light up but no flashing. The D20 LED doesn't turn on at all.

[DSB]

Check the voltages at the cpu input connector J210, You should have 12VDC between pins 1 and 7and 5VDC between pins 1 and 5. Check for any cracked solder on the circuit board at this connector. You could also remove the board and connect it to a test power supply with a 5VDC and 12VDC output to see if the board fires up. This may isolate the problem to the CPU or the power driver board. An old computer power supply will work.

[Retropin]

Thanks robm, but no luck.
Checked all voltages at test points and all within spec.


Checked all fuses all ok.


Any other tips?

DC at test points is Ok? IC's are seated properly?
Check at test points again but put the DMM to AC and see if you get anything. A digital meter often isn't fast enough to detect ripple on the DC but if set to AC you will see it. If anything shows then rectification is faulty which more often than not down to the electrolytic caps.