Dead AIM 65??
cctalk at randy482.com
Fri Apr 15 14:52:09 CDT 2005
From: "Dave Dunfield" <dave04a at dunfield.com>
Sent: Friday, April 15, 2005 1:51 PM
> >PS. while on the topic of 6502's , does anybody know where I can get
>>a pdf online data sheet 68B50 ? Datasheets for the 8 bit stuff is getting
>>harder to find all the time for the original products.
> It's on my website:
> Go to the "Dunfield 6809 Portable" section under "Homebuilts", and
> then on to "Documentation" and "Reference material" - I have a
> scanned 68[AB]50 datasheet there.
> dave04a (at) Dave Dunfield
> dunfield (dot) Firmware development services & tools: www.dunfield.com
> com Collector of vintage computing equipment:
I've started a webpage on bringing up S100 computers but haven't added much
to help here yet.
With a totally dead computer start at the beginning:
1) Check the +5v, if you have a scope check for ripple.
2) Look carefully at everything on the PC board, physical evidence of
badcomponents: resistors & caps turn brown to black. Plastic IC's turn gray
to white. Many components are cracked
3) Check for cold solder joints.
4) Buy a good logic probe, ebay sells them for under $25.
5) If you use a DMM to check logic level remember: If you measure from
ground >3v is high, <3v is not low. To measure low measure from +5. If all
you measure from is ground you won't know if it is open. Logic can be high,
low, or open. An open line may mean the chip driving the line is bad.
6) Start by checking the MPU address lines to see if the addresses are
changing, if not it probably is a bad clock or bad 6502.
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