putting it all together

[newTIboyRob]

Hello mates. So if you have viewed some of my other recent threads, you will know that I have a 2c which, when I turn on, displays the "CHECK DISK DRIVE" error message, with both the internal drive and PR#7 tried external drive. My first thought was: dirty heads.

But I did a little internet digging and found someone who posted a similar issue. Eerily similar. So for my sake, and maybe this will help out others, I culminated all those responses, reviewed and compiled my own forum posts here, and applied everything to my own situation. I now believe that, although I may still have dirty drive heads, that what I am experiencing is more of a hardware issue, more specifically, bad hardware in the form of a bad RAM chip, since there was a display on the screen of flickering "0" characters which are an indicator of faulty RAM. Those did occur when I powered on the machine, with any disk inserted in the drive, before the disk loads, with the flickering inverse characters always being the same "0." I then learned that improperly working RAM would indeed prevent the floppy drives from functioning properly, hence the CHECK DISK DRIVE error message. Since there was a prior mention that the fact that 2 different drives were not working, the problem would stem from the controller of all, thus motherboard related.  When I put all that together with what I then learned, that quite a lot of the original RAM in the IIc bombed, there is a pretty good chance that I now have a viable diagnosis.

 

So, 2 questions:

 

1) I am definitely not the brave, more techie type and I am struggling to find any local repair shops who can open her up and take a look. What have you experienced to be a range for a pro diagnostic checking fee?

If it is merely a RAM chip or chips replacement, those are relatively inexpensive from what I gather, but then there is the repair fee.  In short,  though it will vary, what do you think the approximate total cost or range of cost to fix this, diagnostic fee, part or parts, would be?  This is where I get scared.

 

2) The computer was used sporadically between 1984 and 1994, and maybe only has like 10,000 miles on it, sparse use. It then sat in a box in the basement til the start of the pandemic in 2020, when I took it out and tried it (can't remember the actual outcome, but I believe it was working.)  Now we have my current predicament. So my question is: what often causes RAM chips that were once working perfectly to go bad?  Is it just old age? (so that this could happen randomly, at any time)  Use?   Non-use? 

Now that you know the history of my specific machine, what do you think likely happened in my particular case?

 

Any replies to the above 2 questions appreciated!

 

 

 

  

 

 

[nick3092]

I'm not an expert in this kind of fault, I've been lucky the memory chips in my Apple IIs are still good. But for a time in the life of the //c and IIe they used chips from a manufacturer that have what is now considered a high failure rate. No rhyme or reason as to why they are failing at a higher rate than other manufacturer's chips. The chips in question have an Apple logo and are branded MT4264. But they are really 4164 chips. Other manufacturers used MT chips besides Apple. And users of those devices have also reported higher than normal failure rates.

 

So there is a chance if yours has the MT ram, it could be bad. Some people rip them out on sight. Some only replace them if known to be bad. My childhood IIc came with a different manufacturer though. Mine was bought the year it launched, not sure if that has any relation to the manufacturer used. A couple years ago, I did pick up a IIe full of MT ram both on the main board and the 80col card. No issues with it. So your mileage may vary as far as MT ram is concerned. 

[newTIboyRob]

So it was just a poor quality part  that was doomed to go bad, at any time?  You don't think that old age, or use, or even non-use played any specific factor?  Mine was a birthday present, December 1985.

[nick3092]

As far as MT ram goes, I'm not aware of any factors causing the high failures. Could have been some kind of manufacturing defect.

 

I believe you said your IIc attempts to boot the external drive with a PR#7? That means it's a rom 255. It also means it lacks any kind of built in diagnostics. The next rom revision has a self test, but instead says something along the lines of "AppleTalk offline" when you do a pr#7 instead of trying to boot the external. You can also issue a print peek(64447) to see the rom version. If it's 255, out of luck for a built in ram test. 

[magnusfalkirk]

Yeah his is a ROM 255 that's why he is able to do the PR#7 to try and boot the external drive. If that is failing also then it definitely is a ram problem.

Edited June 27, 2023 by magnusfalkirk