My friend Marco sent me this Jaleco Cybattler PCB for a repair:
PCB was really in mint condition but when I powered it up I got this:
A blank screen and then the dark.First thing to do in this case is to analyze the main CPU, a 68000 on this board.The CPU was resetting properly but after few second /RESET pin was going from high to stay low, at same time also /HALT line was stuck in this logical state.This was a clearly sign of troubles with main code execution so I went to dump the two program ROMs (27C2001 devices) :
When I tried to read the one marked ‘2’ @IC53 my programmer warned me about a problem on PIN32 (VCC), ignoring this obviously resulted in an empty dump :
I programmed a new 27C2001 device and board booted properly but all the background graphics was missing or blocky:
Background graphics data are stored in two 4Mbit MASK ROMs (27C040 compatible) so I went to dump them and resulting files were good.But this didn’t convinced me so I analyzed them with my logic probe and I found that the one @IC67 had all data lines silent :
When I put my finger on the solderside of this MASK ROM I could restore the graphics :
I programmed the 27C040 EPROM as replacement of this bad MASK ROM using the MAME ROM set file and this fixed the board completely.End of job.
Sorry, the comment form is closed at this time.