Hi Guys,

Pinball doesn t boot. No fuses or big transistors are blown.
PSU seems fine, the +5V does lit up but not the other 2 status leds.
3x1.5V voltage seems fine....

Nothing is displayed on the front and strange sounds are emitted when powering on. Sometimes continous beeps, sometimes nothing....

ideas?

Thanks,

Vincent

make sure you have +5, +12, and ground at cpu / driver board. If you do have all the correct voltages to the CPU board then the fault is more than likely on this board. if the voltages are low it will not come out of reset.


  &  to the forum Vincent

 check if you have around +5 volts on the reset circuit on the cpu board. the reset test point will be 0 volts for about half a second or so when you power up the machine, once the voltages have stabilized it will change to around +5 Volts. if you don't then there is possibly a problem in the reset section (if the board has had a battery leak and is acid damaged this is usually the first area that dies) the reset test point is just to the left of I.C. U10 on the cpu board.

If you do have +5 volts on the reset circuit you will need a logic probe to test if the cpu has a clock signal going to it, you may have a dead oscillator on the CPU board.

You could have any thing from a faulty cpu, faulty PIA chip to a power supply problem or faulty I.C. socket. (some system 11 games don't always give a flashing led code when there is a faulty PIA, Ram or rom chip.

You can try reseating connector 1J17 on the CPU board, this is where the cpu gets it's +5, +12 ,-12 from,

Also try unplugging the 2 ribbon cables that connect to the CPU board. some faults on the external sound board and display board can stop the cpu from booting, It's not something that i have seen a lot of but i have seen it happen.

If the machine started doing this after a ribbon cable was unplugged and plugged back in make sure the ribbon cables are correctly connected with the red wire going to pin 1 at both ends. if you have a ribbon cable that has been incorrectly connected this will cause all kinds of dramas.

Make sure you do all your unplugging  and plugging in when the machine is unplugged from the wall. also be careful around the high voltage section of the power supply and the display board because of  the high voltages used to run the display. If you are not familiar with where the high voltage sections are then get some help from some one who does.  

I am not sure of how much experience you have so i thought i would mention this, If i didn't I am sure someone would remind me to mention it