Apple ii Europlus - suddenly throwing up erratic error

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Joined: Jan 12 2011
Posts: 32

Hi All

I have used this forum over many years to help me restore my Apple II Europlus (UK model). The machine has been fully working for many years, but recently I decided to try and fix up some un-serviceable Drive II's using the detailed diagnostics from Speedy G. I suspect it is pure coincidence, but after running tests on one drive, the machine threw an error along the lines of:

EE00- A=DA X=F4 Y=04 P=39 S=E0
*CURSOR

The machine now runs for a few seconds or a few hours, but the error (though the values change each time) always comes. I have always been careful with my connecting / disconnecting protocol with drives and cards.

I have:

- Run various diagnostics software within my library and it always passes the tests of memory, cards, etc.
- Tested the voltage outputs on the power supply (it was rebuilt in the past), they are all within tolerances.
- Reseated chips and removed all cards (it currently has disk controller card, super serial card, and language card fitted).
- The machine received a full set of NOS 4116 chips back in 2011 when I first restored it, as all the Apple ones were fried. I wonder if the problem is a legacy of its past.

I noticed that sometimes, the IC chips (all of them) seem a little hotter than usual, but they stabilise around 27'celcius (all at the same temperature).

Any suggestions gratefully received of how to proceed:

Thank you, Paul

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speedyG's picture
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Joined: Nov 16 2011
Posts: 2413
Re: Apple ii Europlus - suddenly throwing up erratic error

Hello Atomtan,

sounds to me like a Fault of the E8 Rom or the logic that selects that Rom while booting up....
such fault on E8 has happened, been diagnosed and been treated several times here.....
( see search tool field - top right side )
That needs not to be related to the drives ....
maybe just the natural death of an IC.....
pay besides attention to the E8 Rom at location F6
also special attention to the 74LS08 at location H1
and the 74LS138 at location F12
and its no bad idea to recheck the voltages from the powersupply....
a lot of them have reached age where caps die and need to be replaced....
so its good habit to revise the voltages within repeating periods of time ( 2 or 3 times per year ... )

sincerely
speedyG

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Joined: Jan 12 2011
Posts: 32
Re: Apple ii Europlus - suddenly throwing up erratic error

Speedy g

Thank you so much for the advice. Strangely 74ls08 is suffering leg corrosion, which I have carefully cleaned. I will follow through the other points when time allows.

speedyG's picture
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Joined: Nov 16 2011
Posts: 2413
Re: Apple ii Europlus - suddenly throwing up erratic error

Hello Paul,
if the 74LS08 suffered from corrosion....
thats like influenca ! Better also check the socket connections....
rust moves from one metal part to the nighbor part also by contact....
speedyG

__________________

In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....