Apple II Video Issues - Boots OK

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Apple II Video Issues - Boots OK

Hello all

This is my first post on Applefritter. I've used many enjoyable hours reviewing all the excellent posts on Applefritter, as well as the extremely helpful trouble shoot guide at http://www.appleii-box.de.

My rev 4 apple ii that came from the UK has display problems! Everything seems fine for the most part--system beeps, boots, keyboard is responsive, etc--EXCEPT the video is scrambled with vertical lines. See attached photos.

Things I have done:

1) Replaced the crystal/oscillator to be 14.31818 MHZ. I've tried both a new crystal and a working crystal from an Apple ii+
2) Completed the X and O soldering to convert from PAL to NTSC

It's worth noting it had video problems before the above changes when using a PAL to NTSC converter box, so I believe the problem lies elsewhere. I believe the PAL to NTSC is successful

Things I have tried to fix the problem

3) Removed all cards and RAM, except RAM row 1
4) Swap many (if not all) IC from a working Apple ii+ including RAM, dataline chips, ROM chips, databus chips, etc outlined in the troubleshoot guide

No matter what I change in steps 3 and 4 I get the same video problem.

Attatching files

Thanks in advance for any help

AttachmentSize
Image icon Main Board - Front4.01 MB
Image icon Main Board - Back3.99 MB
Image icon Video Error2.36 MB
Image icon FIXED70.44 KB
macnoyd's picture
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Do you get a "Beep" when

Do you get a "Beep" when powering on?
If no, have you swapped out the D0 thru F8 ROMS with known good ones?

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Does the video mode change

Does the video mode change correctly when you type GR, HGR or HGR2?

If it doesnt start looking around the video mode multiplexor (A9) and the video mode select latch (A10).

If graphic modes  seem to work then look around the character generator ROM.

 

 

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FIXED

Got it all, after reading a post from a fellow member about reseating the keyboard ROM. For me it was the A 10 chip. Another apple ii on the grid. Hope this thread helps others in the future.

 

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