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DistantStar001

Apple //e with horizontal bars?

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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?

 

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Does it beep with the speaker connected on reset or powering up ?

 

Sounds like it's stuck in graphics mode. May be an issue with the logic chips which supports signals for softswitches. Check the IOU as well by substitution.

 

Do you have a photo of the board and the screen ?

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3 hours ago, shoestring said:

Does it beep with the speaker connected on reset or powering up ?

 

Sounds like it's stuck in graphics mode. May be an issue with the logic chips which supports signals for softswitches. Check the IOU as well by substitution.

 

Do you have a photo of the board and the screen ?

The picture is from before I swapped out the IOU, but doing so made no difference.   Also there is no beep when powered or reset.

Apple bars.jpg

Apple board.jpg

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Posted (edited)

There's an issue with the boot sequence and the machine isn't starting.

 

Check the F8 ROM first, then the AppleSoft ROM EF. ( locations D8 and D10 ).

 

Did you remove all socketed chips prior to dishwashing ( that's never a good idea ) ?. Check that you didn't bend any pins re-seating.

 

Similar issue at the link below with an Apple II & language card installed. So I would suspect the above ROMs or supporting logic fault. If replacing the ROMs doesn't fix it I'd suspect the two buffer ( 74LS244 ).  If you have a scope or logic probe handy, you can check that the two enables are active ( pulsing ) on the above ROMs or just check the output of the MMU ( pin 19 and pin 20 ), if no pulsing then I'd assume replacement MMU is no good assuming the clock is good which appears it is.  

 

https://forums.macrumors.com/threads/apple-ii-plus-language-card-error-please-help.1699921/

 

Edited by shoestring

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On 8/24/2019 at 7:13 PM, shoestring said:

There's an issue with the boot sequence and the machine isn't starting.

 

Check the F8 ROM first, then the AppleSoft ROM EF. ( locations D8 and D10 ).

 

Did you remove all socketed chips prior to dishwashing ( that's never a good idea ) ?. Check that you didn't bend any pins re-seating.

 

Similar issue at the link below with an Apple II & language card installed. So I would suspect the above ROMs or supporting logic fault. If replacing the ROMs doesn't fix it I'd suspect the two buffer ( 74LS244 ).  If you have a scope or logic probe handy, you can check that the two enables are active ( pulsing ) on the above ROMs or just check the output of the MMU ( pin 19 and pin 20 ), if no pulsing then I'd assume replacement MMU is no good assuming the clock is good which appears it is.  

 

https://forums.macrumors.com/threads/apple-ii-plus-language-card-error-please-help.1699921/

 

It's good news bad news time!  The good news is that thanks to your help, I was able to trace the problem to the CD and EF ROMs.  So my board now works!  The bad news is that the replacement ROMs came from one of my other //e's and I'm now 2 ROMs short to use both boards (worse, they're the un-enhanced versions, and there aren't that many replacements that I'm aware of).  Still, the board works!!! (if you can't tell I'm really happy about that.  And also Thank You!!).  Also, this board is more period appropriate to the case I have.  

The other bad news is that when testing the boards, I found that the 7, =, U, P, K, and , keys on my keyboard had stopped working.  I tested the switches with a multimeter and they seemed fine, but neither board will recognize them.  I think they might just be dirty, but the 99% IPA isn't cutting it.  So I'm wondering what people's thoughts were on the best brands of de-ox-it?

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Do a homer and set up the tapping bird to peck your keyboard keys for a while, and see if extra use will bring them back to life :)

 

  • Haha 1

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1. You don't need the original mask roms, you can program some EPROMs to take their place. There's a guy in Canada who does this as a service, just tell him what you need and provide the binaries and he will send you the chips. I believe you can use 2764s for video and program roms.

 

But I'd save yourself the trouble and just get a kit from here for $25 which will end up being much cheaper. You get the roms, stickers and the 65C02 which will bring your machine up to Enhanced specs.

 

https://www.reactivemicro.com/product/iie-enhancement-kit/

 

2. If you think the issue is mechanical swap over the keyboard from your other IIe and see if the keys work .If its not a mechanical issue, reseat the keyboard decoder next to the connector ( UE14 ) or swap it and see if that resolves.  Also check your ribbon cable as well. 

 

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Posted (edited)
19 hours ago, shoestring said:

1. You don't need the original mask roms, you can program some EPROMs to take their place. There's a guy in Canada who does this as a service, just tell him what you need and provide the binaries and he will send you the chips. I believe you can use 2764s for video and program roms.

 

But I'd save yourself the trouble and just get a kit from here for $25 which will end up being much cheaper. You get the roms, stickers and the 65C02 which will bring your machine up to Enhanced specs.

I already have two enhanced //e's so I was looking to keep a few original.

19 hours ago, shoestring said:

2. If you think the issue is mechanical swap over the keyboard from your other IIe and see if the keys work .If its not a mechanical issue, reseat the keyboard decoder next to the connector ( UE14 ) or swap it and see if that resolves.  Also check your ribbon cable as well. 

I was able to narrow part of my problem to the ribbon, as the problem keys mentioned before show up on both keyboards with that particular ribbon.  However, now the A, and Z keys don't work on the original board regardless of which ribbon, but do work on the alternative board.  Again, I've tested the switches and the traces, and they all seem fine, but the keys won't respond?  I also tried tripping the keys with a screwdriver.  No luck. The other keys worked (screwdriver or switch).  It's just these two keys on this one board?

 

Just tried dome De-Ox-It, no luck.

Edited by DistantStar001
Additional information.

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