RE: R: I: STAR CASTLE PCB with a "little" problem - SOLLVED

From: vernimark <>
Date: Wed Jun 22 2011 - 12:43:58 EDT

HP Logic Comparator... I suggest to use it with the expansion zif socket


I could see the gameplay was not affected by this problem, so I decided to
start from the digital output going back, but the temptation to troubleshoot
the CCPU was stronger than the logic so I began to check RAMs, ROMs, ALU and
so on but everything seemed to work properly. Then I began again from the
video output and… that’s all



[] On Behalf Of John Robertson
Sent: mercoledý 22 giugno 2011 18.34
Subject: Re: R: VECTOR: I: STAR CASTLE PCB with a "little" problem - SOLLVED


vernimark wrote:

As you know I started from this condition:
After some checks the problem was in a faulty 74194 (4-BIT BIDIRECTIONAL
UNIVERSAL SHIFT REGISTERS) in position N4: Secondary accumulator, logic
block 3

74194's seem to fail disproportionally over other TTL.

I too would like to know who you found this one. Did you use the Cine box or
a 'scope? A logic comparator is handy...

John :-#)#

-----Original Message-----
[] On Behalf Of vernimark
Sent: mercoledý 8 giugno 2011 16.43
Subject: RE: R: VECTOR: I: STAR CASTLE PCB with a "little" problem
Monitor is ok (star hawk and armor attack work well), this evening I'll
check the PCB flat connector
-----Original Message-----
[] On Behalf Of Christopher X.
Sent: mercoledý 8 giugno 2011 16.25
Subject: Re: R: VECTOR: I: STAR CASTLE PCB with a "little" problem
On Wed, 8 Jun 2011, vernimark wrote:

I'm sorry for the quality of my video, but if you look it carefully you

can see the "rings" of the castle

shake a little bit. But if you look more carefully the rings don't shake

, they are simply drawn with some

segment vertex wrong for a short time, just a "frame" (I know we don't

have frames in vector games). The same

happens with the animy starship: when it rotates in some positions and for

a very short time, some vertex are

wrong. So definitely it is not a problem limited to one object.
I already changed 181 TTL RAMs and ROMs

If it's all objects then maybe it's one of the DACs, either a stuck pin or
just one "bit" with a desoldered pin.
Chris Candreva -- -- (914) 948-3162
WestNet Internet Services of Westchester


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Received on Wed Jun 22 12:44:21 2011

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