104 lines
5.0 KiB
Plaintext
104 lines
5.0 KiB
Plaintext
Path: apple!sun-barr!olivea!uunet!cis.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!rutgers!att!cbfsb!cbnewsc!rls
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From: rls@cbnewsc.cb.att.com (richard.l.schieve)
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Newsgroups: rec.games.video.arcade
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Subject: Early Williams Tech Tip
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Keywords: Robotron, Joust, Stargate...
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Message-ID: <1992May15.193150.22162@cbnewsc.cb.att.com>
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Date: 15 May 92 19:31:50 GMT
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Distribution: na
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Organization: AT&T
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Lines: 92
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Well, I've been collecting, fixing, and restoring mostly early 80's
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video games for around 8 years now and have gotten pretty good at
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working on them. Some of these games have the same problems over
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and over and I thought some of you might like to hear about some of
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these problems. Much of this is information I've sent directly to
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people when they have posted requests for help. I'm not an
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electronics wizard or anything. I've just spent enough time trying
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to fix games that I've learned some typical failures.
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Todays Tech Tip ;-) is on the early William's games, Defender,
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Joust, Robotron, Stargate, Sinistar, Bubbles, and I think Blaster
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but I've never worked on one. These game all share the same basic
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logic board arrangement as follows:
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------------------- ------------ ------------ -------
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| | | | | | | |
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| | | | | | | AUX |
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| CPU/VIDEO | | ROM/PIA | | SOUND | | SND |
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| | | | | | | |
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| | | | | | | |
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| | ------------ ------------ -------
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| | ----------
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| | | | <--INPUT
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| | ----------
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-------------------
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The three boards on the left are often mounted on a metal plate.
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The sound board is the same one used in pins and the AUX SND board
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is only used in Sinistar (I'm not sure on Blaster).
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The most common problem I've seen with these games are loose
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connections that can become intermittent and sometimes overheat. How
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the loose connections affect on the game depends on where it is.
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All these boards including the power supply boards not shown are
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interconnected with female Molex connectors mating to male pins that
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are mounted perpendicularly to the boards. These male pins are
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fairly heavy gauge and are a bit hard to solder to. The solder
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connection between the board and pin often cracks when taking the
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connectors on and off. Also, at the female end, the connection can
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overheat if things get a bit corroded actually burning the connector
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shell and the female pin looses it's spring tension.
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People often complain of resets during game play. There are some
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software bugs (at least in Robotron) but more often than not the
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resets are due to the +5 VDC supply dropping below what TTL devices
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can operate with at the logic board itself. The Molex connections
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to and from the power supply board will often show signs of
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overheating. Try measuring the +5 at the power supply and again at
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the logic boards. If there is much of a difference and especially
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if the logic board is seeing less than +4.7 or so you have
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problems. If the female end has overheated considerably the female
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pin itself has lost spring tension and should be replaced. Often
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you can clean the male pins and work the female off and on a few
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times to get by for a while but chances are the female pin should be
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removed and replaced. Many hack artist coin-op repair types will
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simply cut off the female connector and solder wires right to the
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male pins. You see the same problems with Williams pinball games.
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BTW, the software Robotron bug is supposed to go away if you turn
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off the "Fancy Attract Mode" which does away with the explosion when
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you zap a bad robot (thanks George).
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Loose connections at the logic boards seem more often to be cracked
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solder joints where the pins go through the boards. Any time
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unexpected things start happening while playing, it is worth the
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time to pull the board and check out the solder joints. I checked
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out about 6 board sets the other day and half didn't work but were
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fine after I resoldered the pins to the boards.
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Also, make sure to clean excess flux after resoldering the pins.
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I've seen too much left over flux scramble the inputs from the
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control panel. To clean excess flux I use 1,1,1-Trichloroethane
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called Carbo-Chor at Ace. It's amazing stuff as as strongly as it
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smells and as well as it works it does not burn so it relatively
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safe to use. I use one of the cheapie stiff bristled "glue" brushes
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and dip it in some trichlor and scrub away.
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To people that have worked on these (and older Williams pinballs)
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this is all old news. I think that many that read this group have
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not had their hands in a machine until they are forced to and often
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have software backgrounds and are a bit afraid of the hardware.
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If this is well received I'll put together some more. If not, sorry
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to have wasted the bandwidth.
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Rick Schieve
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rls@ihlpb.att.com
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