Apple IIe strange issue

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Apple IIe strange issue

Hi everyone,

Very new to owning an Apple computer.

I recently got my hands on a couple of Apple IIe computers.

One is working fine the other seemed to be dead. 

Both have boards Logic Board ID: PCB: 820-0188-A (International) - REV: 607-0288-C in them.

I managed to get the non-working one up again.  It had a short to ground on the 12v line which was caused by  a bad 10uf cap.  Replaced that and we have power LED.

 

Now to the strange issue.  The recently repaired unit started up fine and gave me the APPLE IIE message at the top of the screen and can load disks.  On switching off the computer and back on again I get garbage on the screen and a flashing cursor which allows me to use the keyboard .

Mulitple restarts of the computer gives the same result.  I can however get the machine working again by removing the keyboard cable, switching on the machine without it connected (getting a screen full of garbage), switching off the machine and inserting the keyboard cable again and starting up again.  Computer works and can load disks at this point.

This behavour can be replicated over and over.  I have swapped over every socketed chip from the working machine to the non-working machine and get the same strange issue. 

I suspect it may be one of the 7400 chips getting stuck and for some strange reason corrects itself after performing the start without a keyboard attached.

 

Any ideas on this one?  Would be great to get this machine running stable.

 

Thanks

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Joined: Jun 18 2010 - 13:54
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You don't need to disconnect

You don't need to disconnect the keyboard.

 

It sounds like you are turning on the computer after it has been off for just a few (up to 30) seconds. In that case, the screen will have garbage but the "warmstart flag" might still contain valid data and the machine will not do a cold restart. You could either wait longer before turning on the machine or do a "cold start" by holding down the open-apple key while turning on or when pressing ctrl-reset to do a restart. The keyboard disconnect does a similar cold start but then also runs the diagnostics; either way it clobbers the warmstart flag so that the next reset performs a cold start.

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Joined: Jul 3 2019 - 21:46
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I feel a bit silly now.

I feel a bit silly now.

I have owned an Apple for all of 24 hours now.  I think you are right.  Once I leave the machine for aa little it does start fine.

Thats good news.  No need to do any further repairs.

 

jeffmazur wrote:

You don't need to disconnect the keyboard.

 

It sounds like you are turning on the computer after it has been off for just a few (up to 30) seconds. In that case, the screen will have garbage but the "warmstart flag" might still contain valid data and the machine will not do a cold restart. You could either wait longer before turning on the machine or do a "cold start" by holding down the open-apple key while turning on or when pressing ctrl-reset to do a restart. The keyboard disconnect does a similar cold start but then also runs the diagnostics; either way it clobbers the warmstart flag so that the next reset performs a cold start.

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