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HMG
01-09-2014, 10:46 PM
Got a particularly problematic Life Force PCB here. The 68000 keeps getting its reset line pulsed and the video keeps going out of sync and cutting out. A Mask ROM pertaining to data common to Life Force and Salamander is confirmed dead.

Several of the 74LSXX chips related to the 68k's 9MHz clock signal and the graphics chipset have been replaced. The 68k's clock oscillator has also been replaced. Issues still persist. Any ideas?

Power supply is ATX, 5v is 4.86 on average.

(this thread pertains to the woes of a friend of mine)

Kid Panda
01-09-2014, 10:55 PM
This board is a nightmare, I wish I could help, maybe busty can chime in on this.

HMG
01-10-2014, 03:18 AM
Fortunately, a good update on this board. While testing, the 68k stopped resetting long enough for the board to finish its self test, all ROMs are okay.

Any ideas on the resetting and the bad video sync?

Xian Xi
01-10-2014, 04:36 AM
Shitty work ram.

bustedstr8
01-10-2014, 10:20 AM
It's probably Fujitsu plague. The Fujitsu rams and logic seem to fail in bunches on this board, LS245s being the worst offender.

HMG
01-11-2014, 12:57 AM
My friend said he'll continue searching for bad logic chips before he attempts swapping the work RAM chips.

He found another dead 74LS245 near the 68000's databus (8 least significant bits), solder point 14D. That logic chip was replaced, board boots up now, but the video issues remain. The game will return to its reset loop when the video goes dead.

Any ideas?

Xian Xi
01-11-2014, 04:11 AM
Like mentioned, check all the Fujitsu ones. If there aren't many of them just replace them all.