Troubleshooting an IBM 5155 - (portable personal computer)

From: Kelly Leavitt <CCTalk_at_catcorner.org>
Date: Sat Jan 15 21:06:11 2005

> -----Original Message-----
> From: ard_at_p850ug1.demon.co.uk [mailto:ard_at_p850ug1.demon.co.uk]
> Sent: Saturday, January 15, 2005 9:53 PM
 
> > Qume drive working, but don't know where to go next. I
> guess I could swap
> > the boards between the two units, but that'll only tell me if it is
> > electronic or electro-mechanical.
> >
> > Other than that, any suggestions for figuring out if it is
> alignment, broken
> > sensor, or something electrical?
>
> The alignment adjustments, in general, are what are known as
> 'interchangeability adjustments'. In other words, if they're
> a bit off,
> the drive will be able to format, read, and write its own disks, but
> those disks will not be useable on other drives, and vice versa.
>
> So what you do first is to hook the drive up as B: and try
> formatting a
> blank disk in it. Note that if, for some reason, the machine
> thinks it
> only has one drive, it'll map A: _and_ B: to that drive.
> You'll get some
> obvious messages if this has happened, in which case the problem is
> certainly not just alignment.

Well, I did this and learned something VERY important. The disk only
formatted as 180K. So, it doesn't see that it is a double sided drive. The
same diskette put back in the working drive formatted to 360K. So, how do
these drives tell if they're dealing with SS vs. DS meadia? Does it just
look for a signal from the second head? Is there another sensor that
indicates "yep - double sided". This is how it works with 8" drives. The
index hole is in a physically different spot.

Thank you for all of your help so far!!

> This sounds like track0 sensor problems. I assume you've
> blown the dust
> out of the sensor? If you have a multimeter and logic probe,
> I'll dig out
> the schematic and tell you what to look for.

Yes, I have blown the dust out of the sensors. See above. How do these
drives signal that they are DS? That seems to be where the error is coming
in. Any tips based on the schematic would be of help. Since all I have at
the moment is a DMM and a homemade logic probe, my tools are lacking to
fully solve this problem.

Thanks again,
Kelly

Kelly
Received on Sat Jan 15 2005 - 21:06:11 GMT