Re: IIe disk problems

[Rubywand <rubywand@swbell.net>]

MadCat13 writes ...
> 
> Hi,  I just recieved an Apple IIe unenhanced from a friend.  He said
> that he was tired of trying to fix it.
> 
> The disk drives about half of the time do not respond at all.  The other
> half of the time, when they start reading from boot-up they never stop.
> (only once did I get them to stop with a Dos 3.3 disk in the drive, but
> what poped up was assembly language, I could tell by the symbol code.
> This may be part of the program but I don't know.
> 
> The rom basic works fine and there seems to be no other problems with
> the computer.
> 
> Whenever I try to load though, the computer locks up until I either
> reset or power down.
> 
> My friend said that he replaced the disk controller.
> 
> Does anybody have any ideas what I can check?
> 
> BTW  I have switched the drives (2 to 1 and 1 to 2) and get exactly the
> same results, so I figure that the problem is not in the drives although
> I can't be sure.
 ....

     There are a few easy things to try.

     First, (with power Off) pull the second drive. Squirt some cleaner on a 5.25"
Radio Shack Head Cleaner disk* and stick it into Drive 1 (leave the drive door open)
and turn On the computer. When the drive starts to spin, gently close the drive door
to engage the Cleaner Disk. Let it spin for 20-30 seconds and, then, do a Reset
(press Control and Reset) to stop the drive.

*Note: The drive head is on the bottom. So, open just one side of the Cleaner Disk,
squirt on the juice, and insert the disk with the juiced side facing down.



     Now try booting a known-good** diskette.  

**Note: One thing about the situation you describe is that it does not seem to
eliminate the possibility of messed up software. For example, a screwed up game
program could start and stop the drives at odd times.

If you have any diskettes which you _know_ boot correctly, these are the ones to use
for checking. Otherwise, use diskettes which you are pretty sure boot okay and accept
the chance that testing and swapping drives could be a waste of time.


     Anyway, insert the diskette and enter PR#6 (type in PR#6 followed by Return). 
If it does not boot, try two or three others to make sure that you are not blaming
the computer for a problem which stems from messed up software.

     If the drive works okay, then, so far, so good. In any case, pull it and swap in
the other drive and run it through the same routine.


     Whatever happens with the above, you will, at least eliminate dirty heads as the
problem. (With luck, you may even fix the problem.)


     There are lots of possible outcomes for the above; so, rather than going through
a long 'If this, try this' list, it may speed things up to just mention two or three
possible hardware problems which could fit:

1- One or both of the drives has a messed up Drive Select input. This could flip On
its Data Output at odd times without necessarily spinning the drive. The result would
be to screw up Data input at the Drive Controller. There are other ways a damaged
drive could mess up Data coming from a good drive. Unplugging the bad drive would let
the good drive work correctly.

2- The Slot 6 socket contacts are scummed-up and making poor contact with the Disk
Controller and need to be cleaned with an alcohol swab. (Also, it is a good idea to
clean the Slot contacts on the Disk Controller card.)

3- The IC which selects (turns On) Slots is bombed or has an intermittant output for
Slot 6. (Try moving the Disk Controller card to, say, Slot 5 and doing a PR#5.)

4- The Disk Controller card has a bad IC, loose solder connection to a drive
connector pin, or broken trace.

5- One or both drives are badly out of adjustment for Speed and/or Tracking.

6- One or both drives have some problem other than the ones mentioned earlier. A
fairly common problem is a blown electrolytic capacitor on the Drive Interface
board-- the one you see when you remove the drive case. Evidence of a blown cap is
goo and/or a cap that has its insides spread around.

     For additional information on Drive trouble shooting and adjustment see the
FAQs:

Home site- for downloading or Viewing via an FTP program ...
  ftp://ground.ecn.uiowa.edu/apple2/Faqs/
 
Mirrors- Text formatted for on-line perusing via Netscape, etc. ...
  http://www.grin.net/~cturley/A2.FAQs.and.INFO/CSA2.FAQs/
  ftp://apple.cabi.net/pub/applegs/FAQs.and.INFO/A2.Csa2.FAQs/

HTML web site versions of the FAQs
 http://members.xoom.com/apple_II/faqs.html
 http://home.swbell.net/rubywand/A2FAQs1START.html



     As you can see from the above, a lot of time can be saved if you have one or two
known-good components to swap in-- such as a known-good controller, known-good drive,
known-good IIe, ... .

     Be sure to post anything more you find out about the problem.



Rubywand