Re: Logic levels question 6502A (Missile command)

did you check that 3.3V line for ripple? check the cap filtering it?

it has been a while since I did board repair so please excuse the email if
it is way off base

Art
----- Original Message -----
From: "David Shoemaker" <davids@oz.net>
To: <rasterlist@vectorlist.org>; "'Technical Tools Mail List'"
<techtoolslist@flippers.com>
Sent: Saturday, November 05, 2011 2:33 PM
Subject: [Techtoolslist] Logic levels question 6502A (Missile command)

>I am trying to trouble shoot a board. I am getting some odd responses
> reading the roms. I noticed that the address lines coming from the 6502
> seem to be going high at 3.5 - 3.7 vdc. I suspect this is causing some of
> the ttl to not latch high.
>
>
>
> This is checked through a meter using the fluke to read a particular
> address
> on a loop and using my scope for the same and while running the game.
>
>
>
> Is this a normal value? I don't see any pull-ups on the address lines on
> the schematic.
>
>
>
> David
>
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Received on Sat Nov 5 14:53:59 2011