Re: Lunar Lander Board Problems

At 05:13 PM 3/28/2000 -0500, you wrote:
>Board one: DEAD Lest leave this one alone for now

1) Clean edge connector and socketed chip's pins
2) If possible, verify the ROMZ
3) Check +5v, if missing, there is probably a short somewhere or a dirty edge connector.
4) Using a logic probe, check the crystal. There should also be a divider in there somewhere, that you can check for different frequencies.
5) Put the game in test mode and use the logic probe on the address and data lines on the CPU. You should see activity on all of them. If not, I would suspect a bad CPU.

>Board Two: Has some loose solder joint somewhere that makes the video
>drop from time to time but shakin the board will get it back The real
>issue is as follows,
>When the board is running, The vectors on the screen (upper part of the
>screen mostly) tear to the right as if the monitor needed recapping.
>Also
>when you go the land your spaceship and the game zooms in to the close
>up for landing, the landing spots (2X 5X etc.) are not where they should
>be.
>They are like, middle of the screen. Suggestions?

If you have a scope w/ xy mode, I would check the outputs from the DAC's to see if the image looks right. I'm guessing that the tearing at the top may not be seen, but the landing spots won't. There is probably a stuck pin somewhere (vector ram, maybe?). I'm not sure where to look for this.. I would just poke around a lot with a logic probe unless you have a signature analyzer at your disposal.

>Board 3 : Works for the most part, draws vectors well, but I am missing
>the beep (low on fuel) sound as well as the the first 3 thrust sounds
>(as heard in test mode)
>basically I only have the explosion sound if you crash. Ideas where to
>got from here?

So the sounds work in test mode? I would suspect the roms or sockets. Maybe a good cleaning would do the trick.

Fwiw, I am certainly no expert yet on fixing boards, so I may be pointing you in the wrong direction. I do know that cleaning the edge connector and IC pins do wonders for "fixing" boards, so that should probably be the first thing you do whenever looking at a problem board.

Jon

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Received on Wed Mar 29 08:28:48 2000