Re: Bus failures

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Hi James!

The bus failure will give you clues as to the particular bit that has a
problem, and then you have to check the items that share that line...I use
the diode test of my digital meter (to either ground or Vcc) and compare
similar function lines to see if any are quite different.

Shorts need a different tact, this is covered in one of the early Fluke
newsletters.

I do find that ROMs fail more often than 6532's that are not damaged by
external voltages, and it seems that U3 dies more often than U2 - for some
reason...

If you have been to the FTP site you should find a bunch of examples of
scripts for the 9010, good luck!

John :-#)#

At 11:44 PM 27/03/2003 -0500, James S. Bright wrote:

>So... Keeping in mind that I'd had my 9010 for all of two weeks... I
>have started to develop a decent sys80 program, and that is the board
>set that I am focusing on for the moment. One particular board that I
>had was showing a bus failure. Sometimes I would get bit 1 stuck,
>sometimes bit 7. At first I could not figure out what was going on, so I
>set it down for a few days. I went back to this board tonight and for
>the heck of it, re-tested it with the ROMs removed. Luckily, that was
>the problem.
>
>However, there were some TTL chips that could have also been the
>problem. In general, when you get a bus failure, what's your approach?
>How to you try to narrow it down? I was trying to use my DMM to find a
>short on some of the FF that are on this board. Any other tricks?
>
>Just curious.
>
>--James Bright
>www.QuarterArcade.com
>Restored Arcade Games for your Home

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Received on Fri Mar 28 08:20:12 2003