[Techtoolslist] Logic levels question 6502A (Missile command)

[Art]

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 at oz.net>
To: <rasterlist at vectorlist.org>; "'Technical Tools Mail List'" 
<techtoolslist at 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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