Apple II plus, screen filled with question marks

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Joined: Jun 8 2007
Posts: 213

I recently got a broken Apple II plus off ebay. There are two problems with it:

1. The power supply is bad (I'm currently in the process of fixing it)
2. The processor was mounted in socket wrong (reverse and two pins off)

I pulled the power supply from my IIe, which works, and placed it into my II+. I then power it on to see it doesn't work, which is when I discover the processor was put in wrong and re-seat it. Then I power it on again. This time it powers up. I hear the beep, but the screen is filled with jittering question marks, like this:

The real text is slightly visible behind the blockade of question marks (maybe not in this picture)

But then, if I hold down the reset button, the question marks disappear, and I can see the blinking cursor:

[img]http://s136.photobucket.com/albums/q177/DaveyPocket/?action=view&current=IMG_3460.jpgp/img]

If I let go, the come back. I'm still able to type stuff:

And again, if I hold reset:

The system has a language card installed in expansion port 0 with the RAM connector put in the RAM socket, I pulled the card out and nothing seems to change

I'm not sure exactly what's causing this to happen. I also plugged up a floppy drive, loads programs just fine. If anyone knows what is going on with this system or has a solution, please post. Thank you.

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Offline
Joined: Jun 8 2007
Posts: 213
Sorry,

Images didn't show up. hear they are in order:

gsmcten's picture
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Joined: Oct 4 2005
Posts: 2616
I seem to remember...

Davy,

I seem to remember another thread here that had to do with this exact problem. It's been a while back, but check the Apple II threads. You may find what you're looking for.

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Steven (gsmcten)

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Offline
Joined: Dec 20 2003
Posts: 359
F8 ROM

I couldn't make it out in your pic but the part number on your F8 ROM wouldn't happen to be 341-0004 would it?

Offline
Joined: Jun 8 2007
Posts: 213
No..

The F8 ROM is labeled 341-0020.

Dog Cow's picture
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Joined: Dec 11 2008
Posts: 465
Try plugging SNES controller

Try plugging SNES controller into it.... but maybe that won't work....

Have a look here, maybe you'll find some clues: http://macgui.com/kb/article/759
Apple II Service Notes

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Offline
Joined: Dec 20 2003
Posts: 359
poor contact

One possibility is oxidation on the chip legs leading to poor contact with the socket. If that's the case then reseating the chips would cure it. To reseat the chips, you pry up each chip a little then press it back down. The scraping of the legs against the socket restores contact. I've had to do this a number of times with IIs or II+s. It's a pain as there's a lot of chips.