Apple III won't boot, pattern on screen

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Apple III won't boot, pattern on screen

All,

I purchased an Apple III which displays the attached screen rather than booting.

I  tried the following to no avail:

- reseated all chips, including all memory chips

- cleaned up some rust  and  residue wherever I could see on chips (some was around floppy connection; worst looking  was chip 341-0035-00 which, however, seems to be keyboard encoder, so probably not the culprit)

Any ideas how to proceed fixing this machine are welcome.

 

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I don't know a lot about a

I don't know a lot about a III, but does it do the same self test as the IIe when the keyboard is not attached?  If it throws an error it might be easier to track down. 

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Thank you Spectre. No,

Thank you Spectre. No, actually it never makes it to the self test — this screen appears right on power on.

 

 

 

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Apparently your next port of

Apparently your next port of call is..  Get an O-scope
and check to see if the clock line is getting pulsed on the CPU...

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Thank you Spectre. I happen

Thank you Spectre. I happen to have an oscilloscope even though I am far from skilled using it... let me find Apple III motherborad schematics and technical description, and let me try. I'll update the thread when I know more.

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Last seen: 1 day 7 hours ago
Joined: Aug 4 2019 - 14:02
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Thank you Spectre. I happen

Thank you Spectre. I happen to have an oscilloscope even though I am far from skilled using it... let me find Apple III motherborad schematics and technical description, and let me try. I'll update the thread when I know more.

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