Apple //e with Horizontal Bars?

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Last seen: 5 days 14 hours ago
Joined: Jul 14 2018 - 12:54
Posts: 45
Apple //e with Horizontal Bars?

I've been working on an Apple //e mother board for a while with no luck.  It worked when I got it, and all the ICs are socketed.  So I tried to use it to diagnose another malfunctioning board.  Unfortunately it didn't work, and when I reseated all the original ICs it stopped working all together (no video, no beep).  Finally I decided to give it a run through the dishwasher (figured that I couldn't kill a dead board) and now I get 12 horizontal bars across my screen, each 8 pixels tall.  This is the most life I've gotten out of this thing in months!  


So far I've replaced all the RAM on the machine, the MMU, all the ROMs (Video, EF, CD, and Keyboard), as well as the CPU.  It's made no difference if the keyboard is plugged in or not, and I haven't been able to trip it into a diagnostic mode.  On a lark I popped in a known bad RAM chip and got a series of As and block on the screen.  I swopped out another good chip for bad and got Cs instead of As.  Then I hit Control-Open Apple-Reset, and that put the Cs back to As.  So I know that the computer can react to the keyboard, just not with known good RAM?


Any ideas or suggestions?

Last seen: 6 days 4 hours ago
Joined: May 27 2013 - 13:01
Posts: 817
When a iie logic board has

When a iie logic board has all the chips socketed then that usually means that it is an old revision motherboard. To replace the MMU you need to use the same revision MMU or it might not work. You can find out by doing the self test after the MMU is installed.

Last seen: 8 hours 49 min ago
Joined: Aug 18 2017 - 16:53
Posts: 108
insanitor wrote:To replace


To replace the MMU you need to use the same revision MMU or it might not work.


Are you sure? I know two different MMUs: 344-0010(-B) for the IIe and 344-0011(-B) for IIc. You cannot use a IIc MMU into a IIe.


My IIe with a (US) Rev.A board from the first series runs a 344-0010-B. This do also some German PAL versions here and a Platinum.



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