Life Force PCB stuck in reset loop and experiencing video issues

HeavyMachineGoob

My poontang misses Lenn Yang's wang
10 Year Member
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Apr 3, 2011
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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

The Chinese Kid
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Jun 13, 2010
Posts
12,514
This board is a nightmare, I wish I could help, maybe busty can chime in on this.
 

HeavyMachineGoob

My poontang misses Lenn Yang's wang
10 Year Member
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Apr 3, 2011
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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?
 

bustedstr8

Trollbox Trade Federation,
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Oct 15, 2007
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943
It's probably Fujitsu plague. The Fujitsu rams and logic seem to fail in bunches on this board, LS245s being the worst offender.
 

HeavyMachineGoob

My poontang misses Lenn Yang's wang
10 Year Member
Joined
Apr 3, 2011
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5,815
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

JammaNationX,
15 Year Member
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Dec 1, 2005
Posts
27,748
Like mentioned, check all the Fujitsu ones. If there aren't many of them just replace them all.
 
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