tezza
Veteran Member
These old Apples IIs are not proving easy to ressurect, even with the welcome assistance of several folk on here. The good news is the IIe Platinum has been diagnosed and only needs a replacement ROM, which I've ordered. It's also cleaned up quite well so that's one down.
However, the 5 II+s are another story. None of them fired on power up. Checking the boards, I found two of them had missing components (transistors, capacitors). Some of these looked as if they had just rusted and snapped off. Many of the ICs had rusted legs which just fell off on extraction.
Anyway, cleaning and mixing and matching I've ended up with three workable (clean) boards with all components present and three working PSU (and three clean undamaged cases and keyboards). The Apple II Europlus and two clones. Unfortunately none of them work. They all come up with garbage screens and don't get to the beep. As none of them work, I can't simply do a chip substitution. I suspect several RAM chips might be at fault, and not just one in each unit.
One approach to checking RAM would be to use another working (good) type that uses the same type of RAM as the test machines so I can sort the good RAM from the bad RAM. I've got three computers of this type but using them is not straightforward. The Osborne is a little flaky and I want to avoid using it as a test machine, the TRS-80 model 1 is pristine and I don't want to touch that if I can avoid it and the System 80s all have piggy backed chips with changes in the circuitry so it's not just a case of substitution.
If only I could get one Apple II+ working, I would be able to diagnose all three.
I think I need to delve into the literature and get to know the electronics better. I've got plenty of books which deal with the hardware. It's just a learning curve I was hoping to avoid.
Tez
However, the 5 II+s are another story. None of them fired on power up. Checking the boards, I found two of them had missing components (transistors, capacitors). Some of these looked as if they had just rusted and snapped off. Many of the ICs had rusted legs which just fell off on extraction.
Anyway, cleaning and mixing and matching I've ended up with three workable (clean) boards with all components present and three working PSU (and three clean undamaged cases and keyboards). The Apple II Europlus and two clones. Unfortunately none of them work. They all come up with garbage screens and don't get to the beep. As none of them work, I can't simply do a chip substitution. I suspect several RAM chips might be at fault, and not just one in each unit.
One approach to checking RAM would be to use another working (good) type that uses the same type of RAM as the test machines so I can sort the good RAM from the bad RAM. I've got three computers of this type but using them is not straightforward. The Osborne is a little flaky and I want to avoid using it as a test machine, the TRS-80 model 1 is pristine and I don't want to touch that if I can avoid it and the System 80s all have piggy backed chips with changes in the circuitry so it's not just a case of substitution.
If only I could get one Apple II+ working, I would be able to diagnose all three.
I think I need to delve into the literature and get to know the electronics better. I've got plenty of books which deal with the hardware. It's just a learning curve I was hoping to avoid.
Tez