Re: 70's Midway board problem

Well, let's take two scenarios just so I understand this.

The ram addresses are between 2000-3FFF
Say it's reading an error at bit 59 along any address between 2000-3FFF

(..and this is where I'm going to look dumb 'cause I sometimes forget some of
this)

Would it mean I need to check the rams at bit 4, 5, and 1? or nearby
multiplexers/buffers?

Bit: 7 6 5 4 3 2 1 0
      0 0 1 1 0 0 1 0 = 59

Or lets say it finds an error on bit 12 at 20FF. I can't remember what it was
exactly.

I remember this being easy to troubleshoot. It's intermittant, otherwise I'd
use the old Midway ram tester.

I'm sorry if I sound so confused. :\

Matt

Kev wrote:

> Fluke questions are probably better asked on the TechToolslist.
>
> Bit 12 but what address?
>
> Do you have a known good ram that you could piggyback on the suspected bad
> ram & run the test?
>
> > Hi there. You can tell when I'm having a party coming up when I ask all
> > kinds of 'fixit' questions so I hope nobody minds.
> >
> > I'm working on a Midway Double Play (1977) that has an intermittant ram
> > problem. Using the Fluke 9010a troubleshooter - I'm finding a problem
> > at bit 12. This is probably a really basic question, but how do I
> > determine which chips correspond with bit 12?
> >
> > There are 16 2107B chips on the board.
> >
> >
> > Bit0 - Bit0
> > Bit1 - Bit1
> > Bit2 - Bit2
> > Bit3 - Bit3
> > Bit4 - Bit4
> > Bit5 - Bit5
> > Bit6 - Bit6
> > Bit7 - Bit7
> >
> > Thanks.
> >
> >
> > Matt
> >
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Received on Tue Apr 23 16:55:11 2002