Bad Dudes - Issue on Boot

[neoretro]

Hi All,

Any idea where to start on a bad dudes doing this on boot?

Thanks

Dave

 

[mozie]

Check voltage is good, check edge connector is lined up correctly and edges are clean, pull the chips, check legs are clean and reseat them one by one etc, power on board check slowly push down on chips,see is anything especially hot etc.

 

[TheDaddy]

Like mozzie said , Looks like CPU not running. Could be a number of things after checks.

Dave.

 

[ArcadePCB]

CPU reset and CPU clock checked already? Interrupt input always active (this would be not OK)? If OK, are there chip select signals at the ROMs?

CPU not running may be caused by ROM or RAM problems, bad address decoding logic, problems on data or address bus (stuck at high/low of any bus signal or a not wanted connection between two bus signals. Read/write signal OK? This is just a few possibilities I would check first.

But first of all, I would recommend to check the ROMs, maybe just data is lost in one after all the years and it needs to be reprogrammed only. EPROMs were specified to store data for 25 years only if programmed correctly.

Good luck!