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Arcade King
1st January 2009, 06:21 PM
Got this PCB in the freebie shooter cab.

As always first thing I look for on any PCB im about to repair is the F branded Fujitsu logic chips.

http://www.aussiearcade.com/uploads/AK/IMG_1611.jpg

This brand is the devil! 95% of the problems on pcbs I've repaired over the years are due to these. Doesn't even matter what type of Fujitsu logic either, they are all dying.

Problem: Board constantly resetting, won't boot.
Fix: Dead 74ls138 @ J2 (F chip :b)

Problem: Games running but has graphics corruption and vertical lines through the graphics.
Fix: very common problem I'm finding on any board with Mask roms. Doing a mask rom test reviled a bad rom @ V8. put a 42 pin socket in and replaced it with another mask rom I had on a parts LE board. The equivalent EPROM for LE is 27C800 8 meg 16 bit rom.

Problem: Colours messed up.
Fix: dead outputs on 74ls151's @ J8 and J10. seen this issue before and the other pcb I looked at was loaded with all F branded 151's :b . I expect the rest of the 151's will die on this board soon enough.

Problem: Player 1 trigger not working.
Fix: Using the schematics I traced the problem back to a bad 74ls253 @ M3 (F chip :b)

anyway game fixed, interesting that this game uses an 8 bit processor.

LOTR4U
1st January 2009, 08:41 PM
Shit YEAH you fixed it you cheeky bugger!

Arcade King
1st January 2009, 09:01 PM
Yeah and hopefully I'll be playing it soon too :D

GameDude
3rd January 2009, 02:41 PM
I dont know what it is about the "F" chips.... I know they are not always ****ed but when there is a problem its always them...
I am thinking that maybe they cant handle higher voltages as much as other brands since its a pretty common fix for PCB's acting strange to up the voltage....
The two wec lemans I have both are populated wit the "F" and 90% are ****ed yet all the customs and cpu's are OK! If it was a surge or something like that all the IC's would be rooted....
So yeah "F" = :evil