31 Aug
2011
31 Aug
'11
8:59 p.m.
Finally pulled out the TRS-80 Model II tonight with the intention of
actually working on it for once (shocker!) and trying to get it operational.
It powers up, drive spins, screen comes on, lights glow, etc. Insert
any one of about 20 8" floppies that I have that are specifically for
the Model Ii and.....
Nothing. Well. BOOT ERROR RS, which is translated as, "Disk not in
RadioShack format."
I'd believe it for one or two, but all of them? It seems unlikely,
although I could blame bit-rot perhaps. I'm hoping it has something to
do with the hardware instead.
Popping it open, the unit powers on and the drive head is dropped to the
spinning disk, then lifted, then dropped, then lifted, and the error
occurs. I cannot see if the head is close enough to the disk or not
(and I have *no* idea of the tolerances anyway) and am not sure how I'd
adjust it -- or drive speed, etc. if that's an issue.
So, anyone got ideas? There *is* a remote possibility that all the
disks I got were wiped either by the previous owner or in some sort of
magnetic disaster, but they're well-labeled and came from a working
haul, so I have to imagine that they're still good. Or at least, I'm
hoping they are. (The bits are damned near visible on these things,
after all.)
Your ideas and good guesses welcome and very much appreciated.
Nathan
--
*Nathan E. Pralle*
Computer Geek
www.nathanpralle.com
www.philosyphia.com
www.twitter.com/NPralle
4 Sep
4 Sep
1:20 p.m.
On Wed, 31 Aug 2011, Nathan Pralle wrote:
I'd believe it for one or two, but all of them?
It seems unlikely,
although I could blame bit-rot perhaps. I'm hoping it has something to
do with the hardware instead.
YES
Popping it open, the unit powers on and the drive head
is dropped to the
spinning disk, then lifted, then dropped, then lifted, and the error
occurs. I cannot see if the head is close enough to the disk or not
(and I have *no* idea of the tolerances anyway) and am not sure how I'd
adjust it -- or drive speed, etc. if that's an issue.
Floppy drives operate
with the head in contact.
So, anyone got ideas? There *is* a remote
possibility that all the
disks I got were wiped either by the previous owner or in some sort of
magnetic disaster, but they're well-labeled and came from a working
haul, so I have to imagine that they're still good. Or at least, I'm
hoping they are. (The bits are damned near visible on these things,
after all.)
Perhaps somebody had a malfunctioning drive. It ate the disk. So, he put
the next disk in, and it ate it, also. Sequentially and systematically,
he destroyed every disk.
HOPEFULLY NOT!
5 Sep
5 Sep
1:17 p.m.
Finally pulled out the TRS-80 Model II tonight with the intention of
actually working on it for once (shocker!) and trying to get it operational.
It powers up, drive spins, screen comes on, lights glow, etc. Insert
any one of about 20 8" floppies that I have that are specifically for
the Model Ii and.....
Nothing. Well. BOOT ERROR RS, which is translated as, "Disk not in
RadioShack format."
I'd believe it for one or two, but all of them? It seems unlikely,
although I could blame bit-rot perhaps. I'm hoping it has something to
do with the hardware instead.
Popping it open, the unit powers on and the drive head is dropped to the
spinning disk, then lifted, then dropped, then lifted, and the error
occurs. I cannot see if the head is close enough to the disk or not
(and I have *no* idea of the tolerances anyway) and am not sure how I'd
adjust it -- or drive speed, etc. if that's an issue.
Most 8" drives used AC motors, the speed is set by the frequency of the
power line, and is therefore not something that will drift. A few 8"
drives had electronically-controlled DC motors (ofteh running from a 24V
supply), which can need adjustment. It should be fairly obvious which
yours is.
In any case, don't adjust anything until you have a clear idea what the
problem is!.
So, anyone got ideas? There *is* a remote possibility that all the
disks I got were wiped either by the previous owner or in some sort of
magnetic disaster, but they're well-labeled and came from a working
haul, so I have to imagine that they're still good. Or at least, I'm
hoping they are. (The bits are damned near visible on these things,
after all.)
Your ideas and good guesses welcome and very much appreciated.
I dont; know if they're on-line anywhere,. but Radio Shack publised
excellent Technical Reference and service manuals for theis computers. If
you cna gt them, read them :-)
Some wild guesses of things to check :
Power supply rails for voltage _and ripple_. It's possible some voltages
are onlyused by the disk cotnroller and/or drive, so the machine may
appear to work (other than failing to boot with a disk error) if these are
missing/noisy
Drive head, index sesnor, track 0 sesort dirty
Red data separator PLL not locking. Radio Shack often used analogue PLL
circuits in their data sepaaraotrs. It's posssible this has drifted out
of tolerance. Don't twiddle anything without the manual though
Drive heads out of alignement (but why?)
IC failure. I've had a fair number of Western Digital disk controller ICs
fail over the years.
-tony
3:36 p.m.
On 9/5/11 1:17 PM, "Tony Duell" <ard at p850ug1.demon.co.uk> wrote:
snip
The model II used full height 8 inch drives, I'm pretty sure that they were
AC powered (*motor*) the stepper was powered by 12 or 24 vdc IIRC
Popping it
open, the unit powers on and the drive head is dropped to the
spinning disk, then lifted, then dropped, then lifted, and the error
occurs. I cannot see if the head is close enough to the disk or not
(and I have *no* idea of the tolerances anyway) and am not sure how I'd
adjust it -- or drive speed, etc. if that's an issue.
Most 8" drives used AC motors, the speed is set by the frequency of the
power line, and is therefore not something that will drift. A few 8"
drives had electronically-controlled DC motors (ofteh running from a 24V
supply), which can need adjustment. It should be fairly obvious which
yours is.
In any case, don't adjust anything until you have a clear idea what the
problem is!.
6 Sep
6 Sep
11:12 a.m.
The model II used full height 8 inch drives, I'm
pretty sure that they were
AC powered (*motor*) the stepper was powered by 12 or 24 vdc IIRC
Most 8" drives have AC spindle motors, all the ones I own do. But there's
a mentiuon of a 24V DC spindle motor in the manuals for some drives, so I
guess they existed. It's pretty easy to tell which you have by looking at
the drive thoguh.
Most 8" drives ran the head stepper motor from 24V I think.
Many 8" drives also need a -ve supply (-12V or -5V, in the former case it
may well be regulated down to -5V on the drive PCB) for the analogue
seciton (read amplifier, etc). If that's mising you migth get a drive
that won't read, but that rail may well mot be essential for any other
part of the machine to work. Worth checking all supply voltages at the drive.
-tony
12:27 p.m.
On 9/6/11 11:12 AM, "Tony Duell" <ard at p850ug1.demon.co.uk> wrote:
The drives in the trs-80 model 6000, 16 and 12 had 24V spindle motors IIRC,
they were tandon TM848-2 drives.
The model II
used full height 8 inch drives, I'm pretty sure that they were
AC powered (*motor*) the stepper was powered by 12 or 24 vdc IIRC
Most 8" drives have AC spindle motors, all the ones I own do. But there's
a mentiuon of a 24V DC spindle motor in the manuals for some drives, so I
guess they existed. It's pretty easy to tell which you have by looking at
the drive thoguh.
Most 8" drives ran the head stepper motor from 24V I think.
Many 8" drives also need a -ve supply (-12V or -5V, in the former case it
may well be regulated down to -5V on the drive PCB) for the analogue
seciton (read amplifier, etc). If that's mising you migth get a drive
that won't read, but that rail may well mot be essential for any other
part of the machine to work. Worth checking all supply voltages at the drive.
-tony
12:44 p.m.
On 6 Sep 2011 at 19:12, Tony Duell wrote:
> The model II used full height 8 inch drives,
I'm pretty sure that
> they were AC powered (*motor*) the stepper was powered by 12 or 24
> vdc IIRC
Some later Model IIs, particularly in their Model 16 incarnation,
used half-height Tandon 848 drives. When they work, they're fine,
but there are a couple of design deficiencies that often kick up
problems. The drive uses 24V for the positioner and head-load,
but appears to use 12V for the spindle motor. The 12V is obtained
via a TO-220 7812 regulator that is inadequately heat-sinked.
Fortunately, there's a fuse as well as a 10 ohm resistor in series
with the 24V line, as the input capacitor to the regulator often
fails )probably from the regulator heat) as well. In any case, the
7812 tends to run very hot and some drives have shunt resistors
across the 7812..
Many 8" drives also need a -ve supply (-12V or
-5V, in the former case
it may well be regulated down to -5V on the drive PCB) for the
analogue seciton (read amplifier, etc). If that's mising you migth get
a drive that won't read, but that rail may well mot be essential for
any other part of the machine to work. Worth checking all supply
voltages at the drive.
The Model II was a late 1979 introduction; I'd be very surprised if
any 8" drives manufactured at that time required a -5V supply.
--Chuck
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