Help needed: MM boots then hangs

[Pajo]

Hi everyone, any help with this much appreciated.

I'm just finishing a complete strip and rebuild of my Medieval Madness.  The machine was in pieces for 3 years so the electronics have not been run in that time. Everything was in working order before I started disassembly.

When I power up I am unable to get to test mode however the display does show the progress bar increasing (but no text with the rom version etc) and the playfield and backbox lights are on.  I get a single bong from the video sound card.

The drawbridge goes down and back up again and the merlin hole popper repeatedly fires as does the catapult. I tried changing the switch and diode on the merlin hole and the catapult has a new switch and diode (both diodes are in the right way around).

Once the display progress bar shows "full" the display goes blank, there is no sound other than the one bong. Disconnecting the catapult and merlin popper does not change anything. The pin is then unresponsive to any input other than it will restart the above startup routine if the enter button is pushed on the door switch console.

The CPU led's look correct for a working cpu - bottom one lit, middle one flashing and top one off.  Led 501 on the audio/video card flashes (slower than the cpu flashing led) and on the driver board all the voltage indicator led's 100-105 are lit.

I have replaced all the ribbon cables with new ones but changed back to the old ones to see if this helped but it made no difference. All connector pins were cleaned with contact cleaner and all connector wires were pushed into their connectors to ensure good seating after the connectors were fitted to the boards.  I've also checked the earth contact on the coin door.

With the machine powered up, I am unable to start a game with the start button.  The pin has no balls in it at the moment and after a while the machine seems to go into a lost ball routine by firing solenoids sequentially.

Any ideas where to start? I don't have any spare boards I can swap other than a display (which looks to be ok given the initial status bar is displayed).

[skywalker]

are the ribbon cables fitted right, red line to pin 1,

BTW, Needs balls to start game ?

[Strangeways]

re seat ASIC chip, RAM, Rom and anything else on the MPU board including the cables.

[Dirty daz]

check the plugs on the cpu board are in the correct positions, the ones at the bottom are the switches,  re seat all connectors   sounds like somthing is in the wrong spot or not connected properly

[Pajo]

Thanks for your help everyone, turned out to be an ASIC chip contact problem. I sorted it by spraying contact cleaner into the ASIC socket (board out of the pin) and then lifting the chip by about 1mm from two corners using a pointed o-ring removal tool, then gently pushing the chip back into place. Repeated a few times and then dried the chip with warm air. Once the board was back in place everything worked again.

[Strangeways]

Thanks for your help everyone, turned out to be an ASIC chip contact problem. I sorted it by spraying contact cleaner into the ASIC socket (board out of the pin) and then lifting the chip by about 1mm from two corners using a pointed o-ring removal tool, then gently pushing the chip back into place. Repeated a few times and then dried the chip with warm air. Once the board was back in place everything worked again.

Surprising how many issues are cured just by reseating the ASIC.