Apple ii Europlus restoration - what next?

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Joined: Jan 12 2011
Posts: 32

Hi All

I posted a question on here in January in my quest to get my Apple II Europlus to boot. This machine gets power but displays a screen of alternate lines (one inverse, one not) of numbers and characters. There is no beep, and it does not drop to monitor even if I try to force this.

I pulled together the replies and other tips from elsewhere in here and performed the following work:

- I extracted the 80 column card and the 16k memory card and set them aside.
- I reseated every chip and replaced some of the Texas Instruments memory chips as they had alot of black residue on the legs and I had spare chips from the discarded 16k card.
- Most of the rest of the chips were in great shape, but the chips that had 'El Salvador' on them again had alot of residue which I cleaned off as best I could with a pencil eraser and then some isopropyl alcohol. These were mostly 74S138's.
- I dropped a spare memory chip into the slot where the 16k card piggy backed in.
- I cleaned up the machine and extracted alot of dust out of it(very carefully).

I purchased the machine as a non-runner. I noticed when I first got it that the inside of the case had some dark staining (as if the machine had gotten hot at some point).

Having re-assembled it, it pretty much did the same as before though the characters were '/s' on one line, and '2's on the inverse line except for one digit 3 on the third from bottom line.

As I now also have a working machine, I noticed that the basket case motherboard (especially around the memory chips) was getting 'far hotter' than I expected and significantly more than my working machine.

I am not keen to do a chip swap as I don't want to screw up the working machine, especially with the heating up issue. I suspect that I have two issues, heat and a faulty F0 ROM.

Any advice you guys can offer, with the heating up issue would be gratefully recieved. I wonder if I need to either scrap the machine or look to buy a replacement motherboard. If I need a replacement motherboard, can anyone recommend a source (I see the odd one on ebay, but not many, it is an 820-0044-c). I am based in the UK.

Many thanks for reading and any wisdom you can share.

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Joined: Jun 5 2008
Posts: 382
Re: Apple ii Europlus restoration - what next?

hot chips - might be a negative voltage somewhere it's not supposed to be. Check voltages on all pins on the hot chips.

I think unless the PCB is damaged, it is restorable, with the right spare parts, time, and tools. An oscilloscope really makes these jobs a lot easier. The question is whether it is worth it to you.

The good news is that the video is at least partly working, which is a good starting point.

Regards,
Mike Willegal

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Joined: Jan 12 2011
Posts: 32
Re: Apple ii Europlus restoration - what next?

Mike, thanks for your comments, the RAM chips are the only ones getting warm/hot. I notice that row c are slightly warm, rows d and e are hot.

From previous exchanges I have had on the VCF, I am under the impression you can remove rows of RAM and the machine should still boot. I assume I could remove my hot rows d and e completely, and replace all of the chips in row c from the memory card I have and give it a try.

Is my logic flawed?

I am happy wasting my time and some money trying to fix this machine, I see it as a challenge of my limited knowledge.

amauget's picture
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Joined: Jan 3 2011
Posts: 245
Re: Apple ii Europlus restoration - what next?

Hi Atomtan,

You could also take a look at this troubleshooting guide.

Cheers,

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Antony
Apple II forever

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Joined: Jan 12 2011
Posts: 32
Re: Apple ii Europlus restoration - what next?

Antony, thanks for this which suggests I am working in the right direction which is great. Before I get it back on the bench, do you know if the machine should still boot if it only has RAM chips in row C (rows D and E being left empty) to enable me to start hunting down which RAM chips / connectors are causing the problem.

amauget's picture
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Re: Apple ii Europlus restoration - what next?

Atomtan,

According to another service manual, you can boot the Apple II with only 16Ko of RAM installed at row C.
I won't be able to confirm that until tomorrow but you can make the test : it won't break anything !

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Antony
Apple II forever

amauget's picture
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Joined: Jan 3 2011
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Re: Apple ii Europlus restoration - what next?

Atomtan wrote:

Before I get it back on the bench, do you know if the machine should still boot if it only has RAM chips in row C (rows D and E being left empty) to enable me to start hunting down which RAM chips / connectors are causing the problem.

The test was done. The answer is definitely : YES, it works with only 16 Ko in row C.

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Antony
Apple II forever

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Joined: Jan 12 2011
Posts: 32
Re: Apple ii Europlus restoration - what next?

Antony, many thanks for checking this for me. I am waiting for a new 74LS138 chip to arrive from the US (one was suspect, so I want to swap it) and then it will go back on the bench. I will update the thread after that.

amauget's picture
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Joined: Jan 3 2011
Posts: 245
Re: Apple ii Europlus restoration - what next?

Atomtan,
If you suspect a 138, you can already do a swap between the one in H2 and the one in F12.
F12 is used to enable the ROMs while H2 is only used for Device Select signals. So with no peripheral card at all, the Apple will still boot.

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Antony
Apple II forever