TECH: Asteroids Resetting - *help*

Ok.

So I have this asteroids. There was a black burn area (some of the board
fibre fabric is exposed) because a cap had blown (in betweenD6 and E6) on
the board. Cap was gone already, so I check traces, ok. I changed the D6 &
E6, put a new cap on, saw some squished display in test more. Replaced the
CDE4016BE and one TL081cp. Now I have proper test screen display. Showed
some ROM issues. Re-burned those, now no problems there. Test screen is
fine (also bleeps when I pull test switch, so audio seems ok).

Now... I put it into game mode and the dreaded blinking flashy 1p and 2p
lights... Board is resetting (I can see the clocking on pin 40 of 6502).

So, I think I have narrowed it down to the WDCLR always stays high..
furthermore, input D[output of E5(LS20) pin 8 of the LS42 is always high
(which needs to be low along with A[AB9] & C[AB11] while B[AB10] is high to
activate WDCLR low)

Anyway, for whatever reason, the output of D6[LS02] pin 4 is never high no
matter the pulsing I am seeing on pins 5 and pin 6[R/Wnot B] and I am seeing
pulsing on these. Now I have replaced every chip mentioned here as well,
but to no avail. I cannot figure out why the WDCLR is not happening... What
am I missing in my tracing here? Am I going about this wrong? Should I be
looking elsewhere say how the AB9-11 and the D input?

Any help here would be appreciated.

Thanks Folks

Andy

Andrew Evrovski
HPC Development Director
Cyberplex
t: 902.429.4721 ext.109
f: 902.423.0899
www.cyberplex.com
---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
Received on Tue Oct 2 20:20:58 2001