Dear Experts, I messed up. I wanted to install a SD card in my nice II Europlus and since the case was off, I put the 8-bit card holding the SD converter the wrong way around into the slot. I turn on there is a louder than usual sound and now it is broken. No magic smoke but I broke something. I get an image but it shows pretty random stuff. No characters just green black moving patterns. I am sad please tell me it how to circle the problem or get it running again. Manny thanks!!!
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Apple II Europlus - Help fixing please
- Thread starter DrAlis
- Start date
Additional debug info:
It does a single beep after i turn on. If i blindly type something i get a beep like a syntax error. if i type 'run' i get no beep. So i think something in the graphics department is shot but the main thing might still be running.
I have a running 2e to trade some chips if it helps.
Which chips to change? Any ideas? Many thanks!!!
It does a single beep after i turn on. If i blindly type something i get a beep like a syntax error. if i type 'run' i get no beep. So i think something in the graphics department is shot but the main thing might still be running.
I have a running 2e to trade some chips if it helps.
Which chips to change? Any ideas? Many thanks!!!
Gary C
Veteran Member
What tools do you have for diagnosis ?
A scope will make life easier.
Need to see if you have a signal on B10 pin 5.
A scope will make life easier.
Need to see if you have a signal on B10 pin 5.
Thanks Gary for replying! I have a newly bought tl866 chip tester for my problem and a multimeter so far. It is not much but it is honest work... Most chips I pulled and tested today were fine. The 74LS51 was bad if I tested it correct (tested as 7451). I am trying to find a replacement to proceed. Can I find out if I have signal on B10/5 with my stuff? Thanks, Alex
Wonder if they have cool ideas?
We do not.
Gary C
Veteran Member
If it detects as a 7451, then its probably ok.
I suggested B10 as it has the video signal on it and would allow us to check backwards or forwards until the problem is found.
I do most of my fault finding with a scope, without one it will be hard to advise, but checking all the chips first will be a start.
I suggested B10 as it has the video signal on it and would allow us to check backwards or forwards until the problem is found.
I do most of my fault finding with a scope, without one it will be hard to advise, but checking all the chips first will be a start.
Thanks Gary, I will wait for the replacement 7451 to arrive and report if it helped. Also since I seem to be tinkering more these days, I might as well get a cheap 50EUR chinese scopes from amazon. Getting a good one seems overkill as I am really not on the signal debug skill level. Are these any good or types you recommend?
Gary C
Veteran Member
I have been knee deep in an Osborne, so my Apple II stuff is rusty. Hopefully one of the resident experts will be along for guidance
but if this is to become a hobby, the correct tools are very useful and fairly cheap. Useable CRT scopes can be had for £50 on ebay (one recently sold https://www.ebay.co.uk/itm/115067779963?hash=item1aca92fb7b:g:C6YAAOSwogthbU14, and one for sale https://www.ebay.co.uk/itm/185163041053?hash=item2b1c93c91d:g:cgUAAOSw-RhhkOPd), I wouldn't bother with a cheap Chinese one. I bought a Hameg one and it works fine but replaced it with a modern LCD one which was about £150 mainly because its so much easier to handle (and looks nice) and does storage.
They are a tool though, and can tell you what you want to see and like any tool, you need to learn how to get the best from them (and learn that the 'negative' lead is often connected to mains earth and can give interesting results if you try to measure across a resistor in a psu for example)
MISSION ACCOMPLISHED! Thanks everybody. OK, so let us finish the story for everybody's closure and potential future card twisters. So while waiting for the second replacement 7451, I decided to test all the remaining ICs. Also a friend of mine was able to look up that the 7451 does not behave like the 74LS51.
So almost the last chip I tested was the 74S175 at B1.
And it failed the test also but completely. So I get new hope I try to find a replacement. A quick look at the language card reveals it also has a 74S175. I decide to swap them and, BOOM, I get a nice "Apple ][" welcome after power on. So now all I need is another 74S175. Testing of the SD Adapter Card reveals that it is fried and will prevent booting if inserted. Thank you all for helping with my first chip level repair journey and all the helpful resources you provided.
I was on the wrong track because I realized so late that the 74LS51 apparently isn't broken but not the same as the 7451.
Kind regards and THANK YOU I learned a lot from all of you.
So almost the last chip I tested was the 74S175 at B1.
And it failed the test also but completely. So I get new hope I try to find a replacement. A quick look at the language card reveals it also has a 74S175. I decide to swap them and, BOOM, I get a nice "Apple ][" welcome after power on. So now all I need is another 74S175. Testing of the SD Adapter Card reveals that it is fried and will prevent booting if inserted. Thank you all for helping with my first chip level repair journey and all the helpful resources you provided.
I was on the wrong track because I realized so late that the 74LS51 apparently isn't broken but not the same as the 7451.
Kind regards and THANK YOU I learned a lot from all of you.
Gary C
Veteran Member
Fantastic
The 7451 and the 74ls51 are almost logically the same but without two inputs to two of the and gates. Sometimes chip testers cant totally identify between two chips and mine displays all possible options if you hold the button long enough.
Just the PET to sort now ?
The 7451 and the 74ls51 are almost logically the same but without two inputs to two of the and gates. Sometimes chip testers cant totally identify between two chips and mine displays all possible options if you hold the button long enough.
Just the PET to sort now ?
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