22 Mar
2025
22 Mar
'25
6:49 a.m.
I was wondering if anyone here has experience with the FD55-B with head
load solenoid.
I have a few working ones, but this one is not, and when I look at it,
it differs from the others in that the head "wiggles" up and done on the
side nearest the solenoid.
I can see it is tight on the rail oppose the solenoid, but on the side
nearest, the back of the head does not connect with the rail on the back
(which seems correct, as there is a piece of that extends out and looks
to slot into a sensor.
But, I'd assume the front mount would hug the rail, but it only does on
the top.
By pushing the head close to the disk in use, I can get it to work, so I
think this loose head issue is the only one.
I guess:
* Anyone seen something like this?
* Is this a broken rail mount on the head, or something else?
* If its broken and probably can't be fixed, anyone have a parts FD55-B?
* Can one replace the head on these (it looks like you can, but I admit
I have never changed parts in a drive mech.
Jim
--
Jim Brain
brain(a)jbrain.com
www.jbrain.com
22 Mar
22 Mar
12:23 p.m.
On Sat, Mar 22, 2025 at 5:49 AM Jim Brain via cctalk
<cctalk(a)classiccmp.org> wrote:
I was wondering if anyone here has experience with the FD55-B with head
load solenoid.
There are many different series of Teac FD55s with differences between
them. I've worked on several (meaning I've stripped and rebuilt them
at a lower level than the service manuals suggest).
Whether it has a head load solenoid or not makes little difference.
The head carriage is unchanged.
I have a few working ones, but this one is not, and when I look at it,
it differs from the others in that the head "wiggles" up and done on the
side nearest the solenoid.
The side of the carriage nearest the stepper motor/tension band
positioner has a pair of metal bearing bushes that run on that rail.
The other side, nearest the load solenoid, has a pair of plastic tabs,
one above and one below the rail. My guess is that one of the tabs has
broken off in your drive.
* Anyone seen something like this?
* Is this a broken rail mount on the head, or something else?
I think so.
* If its broken and probably can't be fixed, anyone have a parts FD55-B?
I don't have any spares for these drives. As I said earlier you need
to know the complete model number to get the right drive to take parts
from. It does have to be a -B (double head, 48tpi). The -A is
single-head, the -E (very rare!) and -F are the single and double head
96tpi versions, so the head is designed for a narrower track.
* Can one replace the head on these (it looks like you can, but I admit
I have never changed parts in a drive mech.
Anything is possible apart from skiing through a revolving door :-)
More seriously, I have taken head carriages out and put them back on
Teac FD55s. It's a long job, a lot of other parts have to come off
first (PCB, top front chassis, spindle motor, head load solenoid,
etc). Then you uncouple the tension band (exactly how depends on which
drive series it is), take out the rails and lift out the head carriage
Note that you replace the whole thing, trying to align the top head to
the bottom head if you want to replace only one of them is supposed to
be impossible in the field. It's not but it is not something to do
'for fun'
Anyway, once you've got the new head in, you test it on a scratch
disk, and then you have to do the radial head alignment etc, with a
special CE disk.
-tony
10:29 p.m.
On 3/22/2025 6:23 AM, Tony Duell wrote:
I was pretty sure, given how many screws there are,
that the answer was
yes. I probably should have asked a followup question, questioning
whether it's worth trying to do the fix (without parts, the question is
academic). It's not like the drive is especially rare, though they are
commanding premium prices now (Dave Dunfield graciously sold me a few
over a decade ago at reasonable prices, and they are still running
strong), and I suspect they will only get pricier as time marches on.
On Sat, Mar 22, 2025 at 5:49 AM Jim Brain via cctalk
<cctalk(a)classiccmp.org> wrote:
As noted, it's an FD-55B
(double head, 48TPI), exact model number is
FD-55B-01-U, part number is 19307110-01
I was wondering if anyone here has experience
with the FD55-B with head
load solenoid.
There are many different series of Teac FD55s with differences
between
them. I've worked on several (meaning I've stripped and rebuilt them
at a lower level than the service manuals suggest).
Whether it has a head load solenoid or not makes little difference.
The head carriage is unchanged.
I wasn't sure.
The side of the carriage nearest the stepper motor/tension band
positioner has a pair of metal bearing bushes that run on that rail.
The other side, nearest the load solenoid, has a pair of plastic tabs,
one above and one below the rail. My guess is that one of the tabs has
broken off in your drive.
That was my thought as well.
I don't have any spares for these drives. As I
said earlier you need
to know the complete model number to get the right drive to take parts
from.
Bummer, I know it needed to be a -B, but I was hoping I could rob a part
off a BV or something later, as they are easier to find.
* Can one
replace the head on these (it looks like you can, but I admit
I have never changed parts in a drive mech.
Anything is possible apart from skiing
through a revolving door :-)
More seriously, I have taken head carriages out and put them back on
Teac FD55s. It's a long job, a lot of other parts have to come off
first (PCB, top front chassis, spindle motor, head load solenoid,
etc). Then you uncouple the tension band (exactly how depends on which
drive series it is), take out the rails and lift out the head carriage
Note that you replace the whole thing, trying to align the top head to
the bottom head if you want to replace only one of them is supposed to
be impossible in the field. It's not but it is not something to do
'for fun'
Yeah, I figured it was a head unit or nothing swap.
Anyway, once you've got the new head in, you test it on a scratch
disk, and then you have to do the radial head alignment etc, with a
special CE disk.
Well, before I make too many plans, is anyone in need of other parts
from a drive like this? I assume the head and electronics go first, but
just checking.
Otherwise, if it seems practical to fix the unit, I'll stow in the
"waiting for parts to fix" box.
-tony
--
Jim Brain
brain(a)jbrain.com
www.jbrain.com
23 Mar
23 Mar
7:30 p.m.
I don't have any spares for these drives. As I
said earlier you need
to know the complete model number to get the right drive to take parts
from. It does have to be a -B (double head, 48tpi). The -A is
single-head, the -E (very rare!) and -F are the single and double head
96tpi versions, so the head is designed for a narrower track.
What is so special/rare about the E? I have only seen the -B and -F variants used in most
machines.
-Ali
7:40 p.m.
On Sun, Mar 23, 2025 at 6:30 PM Ali <cctalk(a)ibm51xx.net> wrote:
A = 40 cylinder single head
B = 40 cylinder double head
E = 80 cylinder single head
F = 80 cylnder double head.
Very few machines used an 80 cylinder single head drive, and I suspect
the -F wasn't much more expensive anyway. So the -E model is not at
all common
(I believe C and D were reserved for 77 cylinder (8"?) drives, G is 80
cylinder double head, high density (360RPM? -- 1.2MByte), and H is 80
cylinder double head high density (1.4MByte))
-tony
I don't have any spares for these drives. As
I said earlier you need
to know the complete model number to get the right drive to take parts
from. It does have to be a -B (double head, 48tpi). The -A is
single-head, the -E (very rare!) and -F are the single and double head
96tpi versions, so the head is designed for a narrower track.
What is so special/rare about the E? I have only seen the -B and -F variants used in most
machines. 
8:07 p.m.
On Sun, 23 Mar 2025, Tony Duell via cctalk wrote:
A = 40 cylinder single head
B = 40 cylinder double head
E = 80 cylinder single head
F = 80 cylnder double head.
Very few machines used an 80 cylinder single head drive, and I suspect
the -F wasn't much more expensive anyway. So the -E model is not at
all common
(I believe C and D were reserved for 77 cylinder (8"?) drives, G is 80
cylinder double head, high density (360RPM? -- 1.2MByte), and H is 80
cylinder double head high density (1.4MByte))
C and D might still have been intended for 5.25"; either they made some
and they didn't sell well, or they were waiting to see if there would
become a need. (in case Micropolis made a comeback, or Vector Graphics
decided to make a luggable with half-height drives :-).
Tandon made some somewhat rare Tm400-4M drives (not always marked with the
M!).
Note, that some kids, who weren't around before Y2K, now call half-height
drives, "Full height", and use "half-height" to refer to
quarter-height or
other slim drives.
Were all of the FG (and even the G) dual speed, or did some rely on a
controller supporting a 300K bps transfer?
--
Grumpy Ol' Fred cisin(a)xenosoft.com
8:12 p.m.
On Sun, Mar 23, 2025 at 7:07 PM Fred Cisin via cctalk
<cctalk(a)classiccmp.org> wrote:
Were all of the FG (and even the G) dual speed, or did
some rely on a
controller supporting a 300K bps transfer?
I thought GF meant it combined the capabilities of G and F drives and
thus could handle 'normal' and 'high' density. Whether this means it
just supports 2 write currents or also 2 speeds I am not sure.
-tony
8:21 p.m.
> Were all of the FG (and even the G) dual speed, or
did some rely on a
> controller supporting a 300K bps transfer?
On Sun, 23 Mar 2025, Tony Duell wrote:
I thought GF meant it combined the capabilities of G
and F drives and
thus could handle 'normal' and 'high' density. Whether this means it
just supports 2 write currents or also 2 speeds I am not sure.
and, THAT is a better wording of my question
--
Grumpy Ol' Fred cisin(a)xenosoft.com
11:45 p.m.
On 3/23/25 12:07, Fred Cisin via cctalk wrote:
Were all of the FG (and even the G) dual speed, or did
some rely on a
controller supporting a 300K bps transfer?
AFAIK, all 55FGs at a minimum had pads or zero-ohm resistors that could
be manipulated to provide a 300 RPM spindle speed.
Even the 3.5" FD235HGs were so equipped.
--Chuck
22 Mar
22 Mar
12:38 p.m.
Incidentally there are some photos of FD55s in bits and being
re-assembled in a couple of my flickr albums :
https://www.flickr.com/photos/tony_duell/albums/72177720302114987/
https://www.flickr.com/photos/tony_duell/albums/72177720304931970/
They cover the complete computers (Stride 440 and Philips P2000C) so
most of the photos are not of the drives, but there should be some
that show the head positioner, etc
And here's a home-made version of the positioner-moving tool. Not
essential, but it's useful to have.
-tony
https://www.flickr.com/photos/tony_duell/albums/72177720302945215/
10:31 p.m.
On 3/22/2025 6:38 AM, Tony Duell wrote:
And here's a home-made version of the positioner-moving tool. Not
essential, but it's useful to have.
-tony
https://www.flickr.com/photos/tony_duell/albums/72177720302945215/
That's impressive, was not aware.
Jim
--
Jim Brain
brain(a)jbrain.com
www.jbrain.com
23 Mar
23 Mar
7:28 p.m.
Tony,
That’s pretty clever. So basically you have attached a M3 bolt to a handle/knob?
-Ali
7:42 p.m.
On Sun, Mar 23, 2025 at 6:39 PM Ali via cctalk <cctalk(a)classiccmp.org> wrote:
Yes. There was an official Teac tool like that shown in some of the
service manuals, but no longer available I suspect [1]. The manual
says that if it's not available to simply use an M3 screw and large
washer (turn it with a screwdriver) but it's easier with the knob.
[1] In any case making one was quicker and cheaper than playing
telephone tag trying to get an official one.
-tony
Tony,
That’s pretty clever. So basically you have attached a M3 bolt to a handle/knob?
-Ali
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Tony Duell