tech : battlezone troubles

hi all..

[only read if you are familiar with BZ hardware :]

i'm not going to say i fully understand whats going on in the battlezone
vector state machine because i don't :)

however, what is apparent is that its beating the hell outa me :)

basically thru various jiggling/replacing i got a boardset that is running
blind, the AUX board works perfectly (from a known working set) so its the
avg for sure ;) It runs tet mode fine, makes a blip, and exhibits all the
right signs.. in game mode, you can coin it up and drive the tank about and
fire, but never see a hint of a vector :)

I have done some extensive probing, but seem to be chasing my tail..

the crux of it is, i am measuring a steady LO on the VCTR test pin..

so far i've got the following :

the vector prom at K7 has been swapped out with a known good working one, no
difference.

comparing all the signals here there and everywhere with a working set i can
see that various timing problems are apparent..
namely the LS42 at J7 which seems to be the main source for /LATCH signals
is doing weird stuff.. its outputs are all ok except pins 3 and 4 (/LATCH
2+3) which are stuck HI. however, its inputs are doing stuff, but not the
same 'stuff' as the working board, possibly indicating bad OP0, OP1, OP2
signals..

its basically stuffing up the whole VSM and confusing the hell out of me :)

is there anyone out there who could possibly point me in the direction of
basic VSM troubleshooting procedures? everything seems to be going round in
circles, there must be a procedure, or at least one or two critical
differences that somebody could say for sure it would be X chip doing that..
?? or am i jaded?

thanks for reading..

Andy Welburn
aka P-man
http://www.willowsp.u-net.com/andy/arcade.htm
ICQ : 98378842

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Received on Fri Jan 12 20:38:24 2001