Apple IIc Chip Rot.

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Apple IIc Chip Rot.

Postby Gibsaw on Tue Feb 04, 2014 5:41 pm

Well, it seems I have my second mysterious "chip rot" victim. (The first was a monitor.)

I have a IIc that's working mostly (won't load disks and shows a few bad characters)

It's definitely behaving like faulty RAM. I held down both apples and reset..Mine's been doing various RAM patterns in the HGR screen for some time. It seems to be orderly like it's still going, but it's sure taking a while.

My actual question is... Does anyone know how long the self diagnostic should take to run on an original rev IIc?
"dsakey" on trademe. Apple II's are my thing.
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Re: Apple IIc Chip Rot.

Postby RonTurner on Tue Feb 04, 2014 5:56 pm

One of my IIc has the same problem, a couple of @ on the screen, My IIc also wont boot off a working Disk etc.

Obviously whats happening is the corrupted bytes appear throughout the memory map (not just the screen), so when ProDOS loads into RAM its corrupted and crashed, the loading problem is not your Drive or Disk its Bad RAM.

I haven't opened it yet (on projects to-do one day list) just fixed a IIc monitor, what a nightmare, took two hours to re-assemble (44 screws !), its now working again.
Image
My monitor blew the A/C filter caps (then the fuse) hardest thing ever to take apart to get to the circuit board !

Cool little Apples those IIc 8) one of those brief case computers with the carry handle

will get my IIc out and try the dianostic's test, wont be till next week when I can get to it.

I thought the dianostic test just keeps cycling for ages ? and stops after a random number of cycles
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Re: Apple IIc Chip Rot.

Postby Gibsaw on Tue Feb 04, 2014 7:06 pm

It looks like this on bootup. Those "@" are flickering a little as well, but that could be RAM too. Hard to tell. I wrote a little BASIC memory checker and was definitely getting inconsistencies.

A looping RAM test that runs indefinitely is possibly the case on an "original" ROM ( PEEK(64447)=255 )

My ROM3 IIc ( Peek(64447)=3 ) runs the diags like a IIe platinum. Starts with a lo-res, and does a few things..Takes about 30 seconds and ends with System OK.

This one seems to be doing something that starts briefly in lo-res, goes to HGR and resembles a really thorough bitwalk type check in HGR, but it's hard to tell if it's progressing or not. I lack another original release IIc to try the diags on, so yeah... If someone has one and could tell me what to expect that would be great. :)

I really don't care if it runs for 24 hours as long as I get a result indicating what chip. I don't fancy desoldering 16 x 4264-20s just to nail it down. (although socketing is probably a good idea. It's a lot of labour intensive work.)
"dsakey" on trademe. Apple II's are my thing.
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Re: Apple IIc Chip Rot.

Postby Gibsaw on Fri Feb 07, 2014 10:24 pm

New RAM ordered from the USA. Really wishing these bastards weren't soldered to the board.

Here's hoping I've ordered enough of them to get the job done in spite of my soldering. :)
"dsakey" on trademe. Apple II's are my thing.
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Location: Auckland

Re: Apple IIc Chip Rot.

Postby Gibsaw on Tue Feb 25, 2014 12:44 pm

New RAM has arrived. Packaging left a lot to be desired from the anti-static point of view... Now to nervously begin the process of some piggyback testing.

Oh, and I've FINALLY gotten around to giving my IIgs machines the snip.. (removing the batteries BEFORE they start leaking.)

EDIT: UGH. somehow I managed to post twice. If it's not too much trouble, can you delete this, Tezza?
Last edited by Gibsaw on Tue Feb 25, 2014 1:14 pm, edited 1 time in total.
"dsakey" on trademe. Apple II's are my thing.
Gibsaw
 
Posts: 709
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Location: Auckland

Re: Apple IIc Chip Rot.

Postby Gibsaw on Tue Feb 25, 2014 12:45 pm

New RAM has arrived. Packaging left a lot to be desired from the anti-static point of view... Now to nervously begin the process of some piggyback testing.

Oh, and I've FINALLY gotten around to giving my IIgs machines the snip.. (removing the batteries BEFORE they start leaking. :D )
"dsakey" on trademe. Apple II's are my thing.
Gibsaw
 
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Location: Auckland

Re: Apple IIc Chip Rot.

Postby tezza on Tue Feb 25, 2014 12:53 pm

Soldered-in RAM. It can be a real pain, although I've found old faulty Apple II and PET sockets can cause almost as many problems!

Good luck with the job and let us know the results.
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Re: Apple IIc Chip Rot.

Postby RonTurner on Tue Feb 25, 2014 1:12 pm

Gibsaw wrote:Oh, and I've FINALLY gotten around to giving my IIgs machines the snip.. (removing the batteries BEFORE they start leaking. :D )


Version 1 's ?

note I found my Power PC - G3 use's identical battery holders as GS's Version 3's 8) so it should be possible to remove the battery
holder from one of those, and we know how cheap those sell for :)

Heck I don't run batteries at all in mine, I just took them out and run mine without them, i'm not going to risk it :wink:
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Re: Apple IIc Chip Rot.

Postby Gibsaw on Tue Feb 25, 2014 1:17 pm

One each... The ROM03 has a holder and the ROM01 was soldered in. (I'll probably put in a holder.)
"dsakey" on trademe. Apple II's are my thing.
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