2 Apr
2015
2 Apr
'15
11:18 p.m.
The other day my RD54 just stopped rotating, dead in its tracks, while it
was running. I guessed one of the motor control power transistors may have
failed. I assume they are the series of 6 chunky ones attached to a single
heatsink. I have desoldered them (en-masse) and tested them with a Peak
DCA55 tester, and they all appear to be working. Does anyone have any other
suggestions? Has anyone ever repaired an RD54 control board?
Regards
Rob
3 Apr
3 Apr
8:58 a.m.
Bit of an update. I put the transistors back as they seem to be OK and
applied power to see if probing around would show anything. The Z8 was
getting power, and the transistors did heat up within a few seconds, but the
disk did not spin at all. Is this going to be a problem with the motor
itself?
On a side note, I spotted a component which I can't identify, folded down
above the Z8 and stuck to what looks like an adhesive pad on the PCB. The
can looks a bit mottled/corroded. On another non-working RD54 it seems to be
marked "12039". I am not sure what this component is, although it looks like
it could be a capacitor. Anyone know what this might be?
Regards
Rob
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Robert
Jarratt
Sent: 02 April 2015 23:19
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RD54 Stopped Spinning
The other day my RD54 just stopped rotating, dead in its tracks, while it
was
running. I guessed one of the motor control power
transistors may have
failed. I
assume they are the series of 6 chunky ones attached
to a single heatsink.
I
have desoldered them (en-masse) and tested them with a
Peak
DCA55 tester, and they all appear to be working. Does anyone have any
other
suggestions? Has anyone ever repaired an RD54 control
board?
Regards
Rob
1:15 p.m.
On 04/03/2015 02:58 AM, Robert Jarratt wrote:
On a side note, I spotted a component which I
can't identify, folded down
above the Z8 and stuck to what looks like an adhesive pad on the PCB. The
can looks a bit mottled/corroded. On another non-working RD54 it seems to be
marked "12039". I am not sure what this component is, although it looks like
it could be a capacitor. Anyone know what this might be?
It's not a thermal fuse, is it? I have absolutely zero knowledge of the
RD54 - but thermal fuses are often in cylindrical metal cans and do seem
prone to gaining a mottled appearance over time (although it doesn't appear
to affect them electrically)
cheers
Jules
1:38 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jules
Richardson
Sent: 03 April 2015 13:15
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic and Off-
Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/03/2015 02:58 AM, Robert Jarratt wrote:
> On a side note, I spotted a component which I can't identify, folded
> down above the Z8 and stuck to what looks like an adhesive pad on the
> PCB. The can looks a bit mottled/corroded. On another non-working RD54
> it seems to be marked "12039". I am not sure what this component is,
> although it looks like it could be a capacitor. Anyone know what this
might
be?
It's not a thermal fuse, is it? I have absolutely zero knowledge of the
RD54 - but thermal fuses are often in cylindrical metal cans and do seem
prone
to gaining a mottled appearance over time (although it
doesn't appear to
affect
them electrically)
Not sure how to tell. The component number marked on the board uses the
prefix "Y". So it is unlikely to be a capacitor or a resistor. I measured
its resistance (in circuit) and it is almost 1K ohm, so it seems unlikely to
be a fuse, unless thermal ones have a higher resistance?
Regards
Rob
4:45 p.m.
On Apr 3, 2015, at 5:38 AM, Robert Jarratt
<robert.jarratt at ntlworld.com> wrote:
Not sure how to tell. The component number marked on the board uses the
prefix "Y". So it is unlikely to be a capacitor or a resistor. I measured
its resistance (in circuit) and it is almost 1K ohm, so it seems unlikely to
be a fuse, unless thermal ones have a higher resistance?
Components marked with Y are usually crystals.
Ian
2:17 p.m.
On 2015-04-03 09:58, Robert Jarratt wrote:
Bit of an update. I put the transistors back as they
seem to be OK and
applied power to see if probing around would show anything. The Z8 was
getting power, and the transistors did heat up within a few seconds, but the
disk did not spin at all. Is this going to be a problem with the motor
itself?
Brushes of the motor (if they have them) would be one thing to check.
Check if the motor is getting power?
Johnny
On a side note, I spotted a component which I can't identify, folded down
above the Z8 and stuck to what looks like an adhesive pad on the PCB. The
can looks a bit mottled/corroded. On another non-working RD54 it seems to be
marked "12039". I am not sure what this component is, although it looks like
it could be a capacitor. Anyone know what this might be?
Regards
Rob
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Robert
Jarratt
Sent: 02 April 2015 23:19
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RD54 Stopped Spinning
The other day my RD54 just stopped rotating, dead in its tracks, while it
was
running. I guessed one of the motor control power
transistors may have
failed. I
assume they are the series of 6 chunky ones
attached to a single heatsink.
I
have desoldered them (en-masse) and tested them
with a Peak
DCA55 tester, and they all appear to be working. Does anyone have any
other
suggestions? Has anyone ever repaired an RD54
control board?
Regards
Rob
5:26 p.m.
On 04/03/2015 08:17 AM, Johnny Billquist wrote:
On 2015-04-03 09:58, Robert Jarratt wrote:
If six transistors, then it is brushless (I'm sure that is
true). But, you should check the Hall sensors.
Likely one may have failed. There should be 3 sensors in
the motor, at any time they should be in a state where one
is high and two low, or two high and one low. So, turn the
spindle while checking the 3 sensor signals, all should cycle.
If the sensors are OK, then the logic going from the sensors
through to driving the power transistors is not working.
make sure the crystal oscillator is running, that regulates
the motor speed controller.
Jon
Bit of an update. I put the transistors back as
they seem
to be OK and
applied power to see if probing around would show
anything. The Z8 was
getting power, and the transistors did heat up within a
few seconds, but the
disk did not spin at all. Is this going to be a problem
with the motor
itself?
Brushes of the motor (if they have them) would be one
thing to check.
Check if the motor is getting power?
6:06 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 03 April 2015 17:26
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic and Off-
Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/03/2015 08:17 AM, Johnny Billquist wrote:
Yes, it is 6 transistors.
All this sounds like I am going to have to open up the disk to get inside as the motor is
on the inside. I don't think there is a way to turn the spindle without opening it.
Interestingly at one point it started working again. Then after I put it all back together
again, it stopped working once more. In one case, it seemed to start spinning when I
changed the disk's orientation (on its side rather than flat), almost as if it just
needed a mechanical encouragement to get it moving. But now, no matter how many times I
try, and what different orientations I try, it doesn't work. Does any of that help
with pointing the finger at all?
Regards
Rob
On 2015-04-03 09:58, Robert Jarratt wrote:
If six transistors, then it is brushless (I'm sure that is true). But, you
should
check the Hall sensors.
Likely one may have failed. There should be 3 sensors in the motor, at any
time they should be in a state where one is high and two low, or two high and
one low. So, turn the spindle while checking the 3 sensor signals, all should
cycle.
If the sensors are OK, then the logic going from the sensors through to driving
the power transistors is not working.
make sure the crystal oscillator is running, that regulates the motor speed
controller.
Bit of an update. I put the transistors back as
they seem to be OK
and applied power to see if probing around would show anything. The
Z8 was getting power, and the transistors did heat up within a few
seconds, but the disk did not spin at all. Is this going to be a
problem with the motor itself?
Brushes of the motor (if they have them) would be one thing to check.
Check if the motor is getting power?
6:12 p.m.
On Apr 3, 2015, at 1:06 PM, Robert Jarratt
<robert.jarratt at ntlworld.com> wrote:
...
Interestingly at one point it started working again. Then after I put it all back
together again, it stopped working once more. In one case, it seemed to start spinning
when I changed the disk's orientation (on its side rather than flat), almost as if it
just needed a mechanical encouragement to get it moving. But now, no matter how many times
I try, and what different orientations I try, it doesn't work. Does any of that help
with pointing the finger at all?
I hate to suggest this, but... head stuck to the platter?
(I don?t know if drives like this can do that. I do remember an RF11 that stopped
spinning because a head crashed, melted, and glued itself to the platter solid enough to
stop the spindle motor.)
paul
4 Apr
4 Apr
6:40 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul Koning
Sent: 03 April 2015 18:13
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: RD54 Stopped Spinning
That would not appear consistent with the fact that the disk did spin again (briefly). The
hall effect sensors seem to be the most promising thing to check right now. Just reluctant
to open up the disk at home.
Regards
Rob
On Apr 3, 2015, at 1:06 PM, Robert Jarratt
<robert.jarratt at ntlworld.com>
wrote:
...
Interestingly at one point it started working again. Then after I put it all back
together again, it stopped working once more. In one case, it seemed to start
spinning when I changed the disk's orientation (on its side rather than flat),
almost as if it just needed a mechanical encouragement to get it moving. But
now, no matter how many times I try, and what different orientations I try, it
doesn't work. Does any of that help with pointing the finger at all?
I hate to suggest this, but... head stuck to the platter?
(I don?t know if drives like this can do that. I do remember an RF11 that
stopped spinning because a head crashed, melted, and glued itself to the
platter solid enough to stop the spindle motor.)
3 Apr
3 Apr
6:41 p.m.
On 04/03/2015 12:06 PM, Robert Jarratt wrote:
Yes, it is 6 transistors. All this sounds like I am
going
to have to open up the disk to get inside as the motor is
on the inside. I don't think there is a way to turn the
spindle without opening it.
Some of the older disks in this vintage had the motor
outside the HDA, and there was a little fan on the end of
the motor that cooled the heat sinks, etc. You could see it
by folding the PC board away from the bottom of the drive.
I thought the RD54 was from that family, but I might be
remembering an older drive (RD53??)
Interestingly at one point it started working again.
Then
after I put it all back together again, it stopped working
once more. In one case, it seemed to start spinning when I
changed the disk's orientation (on its side rather than
flat), almost as if it just needed a mechanical
encouragement to get it moving. But now, no matter how
many times I try, and what different orientations I try,
it doesn't work. Does any of that help with pointing the
finger at all? Regards Rob
Well, I'd try wiggling connectors some more and see
if you
can get it to spin up again. Sticky motor bearings and
stuck heads are common on older drives. They put a landing
lube on the park areas of some drives, and that eventually
glued the heads to the disk, requiring more torque that the
spindle drive was allowed to provide.
But, your drive spun down while running, which is not
connected to that scenario.
Jon
6:44 p.m.
I am going to try to answer several points together.
The mystery component sounds like a crystal or ceramic resonator. Does it connect directly
to the Z8, if
so, to what pins? 1k is a very low DC resistance for such a component, though (was this
tested out-of-circuit)?
The RD54 is a Maxtor XT1140 or something similar. The spindle motor is a 3 phase
electronically-commutated
thing (no brushes -- does _any_ small hard disk have brushes in the spindle motor [1]). It
is entirely within the
HDA, there must be some hall effect sensors that are part of it (inside the HDA too) for
position feedback.
Alas I have never seen a schematic for this drive (it's not on bitsavers that I can
find) so I don't know many
details.
Assuming the power transistors are good, then the most likely fault is a failed hall
effect sensor, inside the HDA.
If we could find a pinout of the motor cable, or a schematic for the drive, it would be
possible to see what is
going on there.
[1] Some larger hard drives, the Diablo 30 springs to mind, had brush-type DC permanent
magnet spindle
motors (and in the case of the Diablo 30, positioner motors, but that is another saga).
Many full-height
5.25" floppy drives have permananet magnet brush-type spindle motors (belt driven to
the actual spindle.
But I have never seen an 8" or 5.25" winchester drive that does.
Interestingly at one point it started working again.
Then after I put it all back together again, it stopped working
once more. In one case, it seemed to start spinning when I changed the disk's
orientation (on its side rather
than flat), almost as if it just needed a mechanical encouragement to get it moving. But
now, no matter how
many times I try, and what different orientations I try, it doesn't work. Does any of
that help with pointing the
finger at all?
Maybe if one hall sensor or drive to one of the motor phases has failed then turning the
drive moved the spindle
just enough to get another motor phase energised and it started running (possibly not on
all 3 phases properly),
-tony
9:14 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
duell
Sent: 03 April 2015 18:44
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: RD54 Stopped Spinning
I am going to try to answer several points together.
The mystery component sounds like a crystal or ceramic resonator. Does it
connect directly to the Z8, if so, to what pins? 1k is a very low DC
resistance
for
such a component, though (was this tested
out-of-circuit)?
No, it was tested in circuit. It is rather hard to tell what it is connected
to actually, the traces are not clear as there seem to be a couple of
layers, and probing with a DMM appears to show it not connected to anything
on the Z8.
The RD54 is a Maxtor XT1140 or something similar. The spindle motor is a 3
phase electronically-commutated thing (no brushes -- does _any_ small hard
disk have brushes in the spindle motor [1]). It is entirely within the
HDA, there
must be some hall effect sensors that are part of it
(inside the HDA too)
for
position feedback.
Alas I have never seen a schematic for this drive (it's not on bitsavers
that I
can
find) so I don't know many details.
Assuming the power transistors are good, then the most likely fault is a
failed
hall effect sensor, inside the HDA.
If we could find a pinout of the motor cable, or a schematic for the
drive, it
would be possible to see what is going on there.
There is a partial printset on bitsavers, but sadly it seems to be missing
the real meat.
(http://www.mirrorservice.org/sites/www.bitsavers.org/pdf//dec/disc/MP02291_
RD54_sch_Jun87.pdf).
[1] Some larger hard drives, the Diablo 30 springs to mind, had brush-type
DC
permanent magnet spindle
motors (and in the case of the Diablo 30, positioner motors, but that is
another
saga). Many full-height
5.25" floppy drives have permananet magnet brush-type spindle motors (belt
driven to the actual spindle.
But I have never seen an 8" or 5.25" winchester drive that does.
> Interestingly at one point it started working again. Then after I put it
all
back
together again, it stopped working
> once more. In one case, it seemed to start spinning when I changed the
disk's
orientation (on its side rather
> than flat), almost as if it just needed a mechanical encouragement to
get it
moving. But now, no matter how
> many times I try, and what different orientations I try, it doesn't
work.
Does
any of that help with pointing the
then
finger at all?
Maybe if one hall sensor or drive to one of the motor phases has failed turning the drive moved the spindle
just enough to get another motor phase energised and it started running
(possibly not on all 3 phases properly),
That is consistent with what happened.
It looks like I would need to open up the drive. Of course I don't have
access to a clean room. Does anyone have any advice or suggestions on how to
make a "clean*er*" room in an ordinary home?
Regards
Rob
4 Apr
4 Apr
4 a.m.
On Fri, Apr 3, 2015 at 11:44 AM, tony duell <ard at p850ug1.demon.co.uk> wrote:
The RD54 is a Maxtor XT1140 or something similar.
The RD54 is a Maxtor XT2190, which, as you say, is quite similar to
the XT1140. Both have 15 data heads (eight platters), but the XT2190
has a higher cylinder count (1224 vs 918), reportedly at least in part
due to use of a better head design.
Maxtor pioneered the use of the drive motor integrated in the spindle,
which is what allowed them to fit eight platters into a 5 1/4" drive
in 1983, when other vendors were limited to four platters.
6:41 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Eric Smith
Sent: 04 April 2015 04:01
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: RD54 Stopped Spinning
On Fri, Apr 3, 2015 at 11:44 AM, tony duell <ard at p850ug1.demon.co.uk>
wrote:
Hmm... does that mean it might be difficult to reach/see/replace the hall effect sensors?
Regards
Rob
The RD54 is a Maxtor XT1140 or something similar.
The RD54 is a Maxtor XT2190, which, as you say, is quite similar to the XT1140.
Both have 15 data heads (eight platters), but the XT2190 has a higher cylinder
count (1224 vs 918), reportedly at least in part due to use of a better head
design.
Maxtor pioneered the use of the drive motor integrated in the spindle, which is
what allowed them to fit eight platters into a 5 1/4" drive in 1983, when other
vendors were limited to four platters. 
9:59 a.m.
Robert Jarratt wrote:
Difficult? Hmm.. I would say they are some of the last things you see if
you dismount the entire drive including the stack of platters.
This is not the way to repair the drive.
Try to find out if the Motor Coils are ok and connect a scope to the phases
to see what's going on after power up.
I've repaired several old disks with different failures and opended them
at home, but this isn't really what you want and you should avoid doning
this if possible. Some people say doing this in the kitchen a boiling put
of water nearby is the best you can do to avoid dust ..
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Freiberger Stra?e 42, 09600 Obersch?na, USt-Id: DE253710583
www.tsht.de, info at tsht.de, Fax +49 3731 74200, Mobil: 0172 8790 741
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Eric Smith
Sent: 04 April 2015 04:01
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: RD54 Stopped Spinning
On Fri, Apr 3, 2015 at 11:44 AM, tony duell <ard at p850ug1.demon.co.uk>
wrote:
Hmm... does that mean it might be difficult to reach/see/replace the hall effect
sensors?
Regards
Rob The RD54 is a Maxtor XT1140 or something similar.
The RD54 is a Maxtor XT2190, which, as you say, is quite similar to the XT1140.
Both have 15 data heads (eight platters), but the XT2190 has a higher cylinder
count (1224 vs 918), reportedly at least in part due to use of a better head
design.
Maxtor pioneered the use of the drive motor integrated in the spindle, which is
what allowed them to fit eight platters into a 5 1/4" drive in 1983, when other
vendors were limited to four platters.
10:55 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Holm
Tiffe
Sent: 04 April 2015 10:00
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: RD54 Stopped Spinning
Robert Jarratt wrote:
>
>
> > -----Original Message-----
> > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of
> > Eric Smith
> > Sent: 04 April 2015 04:01
> > To: General Discussion: On-Topic and Off-Topic Posts
> > Subject: Re: RD54 Stopped Spinning
> >
> > On Fri, Apr 3, 2015 at 11:44 AM, tony duell
> > <ard at p850ug1.demon.co.uk>
> > wrote:
> > > The RD54 is a Maxtor XT1140 or something similar.
> >
> > The RD54 is a Maxtor XT2190, which, as you say, is quite similar to
the
XT1140.
> > Both have 15 data heads (eight platters), but the XT2190 has a
> > higher cylinder count (1224 vs 918), reportedly at least in part due
> > to use of a better head design.
> >
> > Maxtor pioneered the use of the drive motor integrated in the
> > spindle, which is what allowed them to fit eight platters into a 5
> > 1/4" drive in 1983, when other vendors were limited to four platters.
>
> Hmm... does that mean it might be difficult to reach/see/replace the
hall
effect sensors?
you
Regards
Rob
Difficult? Hmm.. I would say they are some of the last things you see if dismount the entire drive including the stack of
platters.
This is what is worrying me. I suspect this would be a very difficult
repair. I have enough bad RD54s that I suppose I could sacrifice one to work
out how to do it (if at all!).
This is not the way to repair the drive.
Try to find out if the Motor Coils are ok and connect a scope to the
phases to
see what's going on after power up.
Is there a good resource on the theory so I can work out how it all works
and what to expect when I use a scope? Wikipedia has some stuff, but it is
all a bit theoretical.
I've repaired several old disks with different
failures and opended them
at
home, but this isn't really what you want and you
should avoid doning this
if
possible. Some people say doing this in the kitchen a
boiling put of water
nearby is the best you can do to avoid dust ..
Nice idea, one to try!
Thanks
Rob
5:29 p.m.
On 04/04/2015 12:41 AM, Robert Jarratt wrote:
Hmm... does that mean it might be
difficult to reach/see/replace the hall effect sensors?
On the older drives with external motors, the Hall sensors
would usually be on a ring-shaped PC board against the drive
housing. So, you'd have the pull the external magnet
assembly off the motor, change the sensor and reassemble.
A very difficult job, but technically feasible at least on
some drives. If the motor is entirely internal, it is
unlikely you can do this. You would have to safely back the
heads off the platters, then remove the clamp and remove all
the platters and spacers off the motor. Then, you'd have to
press the platter hub/motor magnet assembly off the shaft,
replace the sensor and get it all back together again, and
get all the platters back correctly. The CIA might be
willing to do this to recover Osama bin Laden's files, but
seems WAY out of the realm for doing it at home.
I've disassembled a number of hard drives over the years, so
i know a bit about how the motors are constructed.
Jon
7:38 p.m.
here the schematics of the XT 1140 from a basic four manual
http://www.ardiehl.de/basicfour/download/mai2000/Maxtor_XT-1140_Schematics.…
On 04/03/2015 07:44 PM, tony duell wrote:
I am going to try to answer several points together.
The mystery component sounds like a crystal or ceramic resonator. Does it connect
directly to the Z8, if
so, to what pins? 1k is a very low DC resistance for such a component, though (was this
tested out-of-circuit)?
The RD54 is a Maxtor XT1140 or something similar. The spindle motor is a 3 phase
electronically-commutated
thing (no brushes -- does _any_ small hard disk have brushes in the spindle motor [1]).
It is entirely within the
HDA, there must be some hall effect sensors that are part of it (inside the HDA too) for
position feedback.
Alas I have never seen a schematic for this drive (it's not on bitsavers that I can
find) so I don't know many
details.
Assuming the power transistors are good, then the most likely fault is a failed hall
effect sensor, inside the HDA.
If we could find a pinout of the motor cable, or a schematic for the drive, it would be
possible to see what is
going on there.
[1] Some larger hard drives, the Diablo 30 springs to mind, had brush-type DC permanent
magnet spindle
motors (and in the case of the Diablo 30, positioner motors, but that is another saga).
Many full-height
5.25" floppy drives have permananet magnet brush-type spindle motors (belt driven to
the actual spindle.
But I have never seen an 8" or 5.25" winchester drive that does.
--
----------------
Gr?sse
Armin Diehl
ad at ardiehl.de
Interestingly at one point it started working
again. Then after I put it all back together again, it stopped working
once more. In one case, it seemed to start spinning when I changed the disk's
orientation (on its side rather
than flat), almost as if it just needed a mechanical encouragement to get it moving. But
now, no matter how
many times I try, and what different orientations I try, it doesn't work. Does any of
that help with pointing the
finger at all?
Maybe if one hall sensor or drive to one of the motor phases has
failed then turning the drive moved the spindle
just enough to get another motor phase energised and it started running (possibly not on
all 3 phases properly),
-tony
8:57 p.m.
here the schematics of the XT 1140 from a basic four
manual
http://www.ardiehl.de/basicfour/download/mai2000/Maxtor_XT-1140_Schematics.…
Thanks for that, it is something I have been looking for for some time.
Page 9 of that .pdf seems to show the spindle motor controller. My guess is the 3 signals
H1, H2, H3 are the signals from the 3 hall sensors in the motor. I think I would start by
seeing what is there (look as though they should be TTL signals, so easy to check) and
also see what the Z8 is sending to the motor driver circuits.
Y1 is the clock crystal, see page 12 of that pdf. I assume it is oscillating, do you see
the
expected 6MHz on pin 9 of U41?
I don't think it'll be possible (or at least not at all easy to replace the hall
sensors. My guess is that
the angular position of the platters is critical and they won't centralise accurately
enough either.
So I would only dismantle the HDA as a (very) last resort.
-tony
10:06 p.m.
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of tony
duell
Sent: 04 April 2015 20:57
To: General Discussion: On-Topic Posts
Subject: RE: RD54 Stopped Spinning
is the
here the schematics of the XT 1140 from a basic
four manual
http://www.ardiehl.de/basicfour/download/mai2000/Maxtor_XT-
1140_Schema
tics.pdf
Thanks for that, it is something I have been looking for for some time.
Page 9 of that .pdf seems to show the spindle motor controller. My guess 3 signals H1, H2, H3 are the signals from the 3 hall
sensors in the motor.
I think
I would start by seeing what is there (look as though
they should be TTL
signals,
so easy to check) and also see what the Z8 is sending
to the motor driver
circuits.
Y1 is the clock crystal, see page 12 of that pdf. I assume it is
oscillating, do
you
see the expected 6MHz on pin 9 of U41?
I don't think it'll be possible (or at least not at all easy to replace
the
hall
sensors. My guess is that the angular position of the
platters is
critical and they
won't centralise accurately enough either.
So I would only dismantle the HDA as a (very) last resort.
-tony
=
So when I fired it up again with the scope, the disk started to spin. This
was a stroke of luck as I was able to probe what I believe were the outputs
of the hall sensors. All three oscillated, but one of them showed
significant sideways wobble on the scope, which suggests to me that the
signal is not absolutely regular. It does seem to suggest that one of the
sensors is not working well. However, would this be enough to explain why it
stopped dead in its tracks when it was working before?
Changing one of these sensors is probably going to be beyond me :-(
Thanks
Rob
10:17 p.m.
On 04/04/2015 04:06 PM, Robert Jarratt wrote:
So when I fired it up again with the scope, the disk
started to spin. This was a stroke of luck as I was able
to probe what I believe were the outputs of the hall
sensors. All three oscillated, but one of them showed
significant sideways wobble on the scope, which suggests
to me that the signal is not absolutely regular. It does
seem to suggest that one of the sensors is not working
well. However, would this be enough to explain why it
stopped dead in its tracks when it was working before?
Yes, the logic is generally
that you decode 6 legal states
of the Hall sensors to decide which of the 3 motor terminals
to drive high and low. if the Hall sensors give a signal
that has all 3 high, or all 3 low, the decode logic will
fail, generally leaving all transistors off. If it gets in
that state again, a vigorous twist of the drive around the
spindle axis might shift the rotor to a position where it
will start up again.
Changing one of these sensors is probably going to be
beyond me :-( Thanks Rob
I'd get the data off it quickly and retire the drive.
You
may only have a few minutes run time before the sensors go
more flaky and the drive shuts off. But, now that you know
the secret, you ought to be able to recover data, if that is
the plan.
Anyway, it seems you have completely diagnosed the problem.
Jon
10:51 p.m.
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 04 April 2015 22:18
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/04/2015 04:06 PM, Robert Jarratt wrote:
sensors to
So when I fired it up again with the scope, the
disk started to spin.
This was a stroke of luck as I was able to probe what I believe were
the outputs of the hall sensors. All three oscillated, but one of them
showed significant sideways wobble on the scope, which suggests to me
that the signal is not absolutely regular. It does seem to suggest
that one of the sensors is not working well. However, would this be
enough to explain why it stopped dead in its tracks when it was
working before?
Yes, the logic is generally that you decode 6 legal states of the
Hall decide which of the 3 motor terminals to drive high
and low. if the Hall
sensors
give a signal that has all 3 high, or all 3 low, the
decode logic will
fail, generally
leaving all transistors off. If it gets in that state
again, a vigorous
twist of the
drive around the spindle axis might shift the rotor to
a position where it
will
start up again.
few
Changing one of these sensors is probably going
to be beyond me :-(
Thanks Rob
I'd get the data off it quickly and retire the drive. You may only
have a minutes run time before the sensors go more flaky and
the drive shuts off.
But,
now that you know the secret, you ought to be able to
recover data, if
that is
the plan.
Anyway, it seems you have completely diagnosed the problem.
Thanks. There is no critical data on the drive. I just wanted to use it to
show my MicroVAX II at DEC Legacy (in the UK next week) working without
booting off a network :-(
Regards
Rob
5 Apr
5 Apr
8:55 a.m.
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 04 April 2015 22:18
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/04/2015 04:06 PM, Robert Jarratt wrote:
sensors to
So when I fired it up again with the scope, the
disk started to spin.
This was a stroke of luck as I was able to probe what I believe were
the outputs of the hall sensors. All three oscillated, but one of them
showed significant sideways wobble on the scope, which suggests to me
that the signal is not absolutely regular. It does seem to suggest
that one of the sensors is not working well. However, would this be
enough to explain why it stopped dead in its tracks when it was
working before?
Yes, the logic is generally that you decode 6 legal states of the
Hall decide which of the 3 motor terminals to drive high
and low. if the Hall
sensors
give a signal that has all 3 high, or all 3 low, the
decode logic will
fail, generally
leaving all transistors off. If it gets in that state
again, a vigorous
twist of the
drive around the spindle axis might shift the rotor to
a position where it
will
start up again.
few
Changing one of these sensors is probably going
to be beyond me :-(
Thanks Rob
I'd get the data off it quickly and retire the drive. You may only
have a minutes run time before the sensors go more flaky and
the drive shuts off.
But,
now that you know the secret, you ought to be able to
recover data, if
that is
the plan.
Anyway, it seems you have completely diagnosed the problem.
Jon
I checked again this morning, because something was bothering me. I realised
that the pins I was observing with the scope were the D pins on the FETs and
not the hall effect sensor outputs. When I went back to measure the sensor
output properly the outputs looked fine and perfectly stable. The outputs
from the Z8 also looked fine. The outputs of the
inverters into the FETs
looked stable, although not square (pics here:
http://1drv.ms/1a39cwz here:
http://1drv.ms/1a39kfs and here: http://1drv.ms/1a39pju). It is only the
output of one of the FETs that looks a bit unstable, but that could be a
triggering problem because the signal is a bit irregular (pic here:
http://1drv.ms/1a39ymO), the other two FETs have similarly shaped outputs
but do not wobble in the same way. I wonder if replacing that FET might do
the trick? Or is the inverter the problem as the inputs are perfectly
square?
Incidentally, the last few times, the disk has fired up every time.
Regards
Rob
4:25 p.m.
I suppose that is possible, but not sure that would explain the dead stop, although I
suppose it isn't impossible. I was nowhere near it when it happened. Do the signals I
posted look right to you? Would you expect inconsistent triggering on the scope on just
one of the FET outputs?
-----Original Message-----
From: "tony duell" <ard at p850ug1.demon.co.uk>
Sent: ?05/?04/?2015 14:44
To: "General Discussion: On-Topic Posts" <cctech at classiccmp.org>
Subject: RE: RD54 Stopped Spinning
Incidentally, the last few times, the disk has fired up every time.
It's not something silly like a bad contact on one of the PCB-HDA connectors. is it?
-tony
5:54 p.m.
On 04/05/2015 02:55 AM, Robert Jarratt wrote:
Do the gate signals not have the wobble? (Wobble could be
the PWM of the speed control logic, so could be normal.)
If so, then the FET may be bad. In fact, the FET may be
entirely OPEN, and the waveform you see is coming from the
other two driven phases.
Kind of strange that one gate signal is a smooth ramp, the
others have some wave on the top.
But, the drive probably has a current sense resistor in the
common source leg of the low-side transistors, so that is
feeding some of the current waveform back to the gates. So,
it may well be the one with the linear ramp on the top
indicates the drain is open.
Jon
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 04 April 2015 22:18
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/04/2015 04:06 PM, Robert Jarratt wrote:
sensors to
So when I fired it up again with the scope, the
disk started to spin.
This was a stroke of luck as I was able to probe what I believe were
the outputs of the hall sensors. All three oscillated, but one of them
showed significant sideways wobble on the scope, which suggests to me
that the signal is not absolutely regular. It does seem to suggest
that one of the sensors is not working well. However, would this be
enough to explain why it stopped dead in its tracks when it was
working before?
Yes, the logic is generally that you decode 6 legal states of the
Hall decide which of the 3 motor terminals to drive
high and low. if the Hall
sensors
give a signal that has all 3 high, or all 3 low,
the decode logic will
fail, generally
leaving all transistors off. If it gets in that
state again, a vigorous
twist of the
drive around the spindle axis might shift the
rotor to a position where it
will
start up again.
few
Changing one of these sensors is probably going
to be beyond me :-(
Thanks Rob
I'd get the data off it quickly and retire the drive. You may only
have a minutes run time before the sensors go more flaky
and the drive shuts off.
But,
now that you know the secret, you ought to be
able to recover data, if
that is
the plan.
Anyway, it seems you have completely diagnosed the problem.
Jon
I checked again this morning, because something was bothering me. I realised
that the pins I was observing with the scope were the D pins on the FETs and
not the hall effect sensor outputs. When I went back to measure the sensor
output properly the outputs looked fine and perfectly stable. The outputs
from the Z8 also looked fine. The outputs of the inverters into the FETs
looked stable, although not square (pics here: http://1drv.ms/1a39cwz here:
http://1drv.ms/1a39kfs and here: http://1drv.ms/1a39pju). It is only the
output of one of the FETs that looks a bit unstable, but that could be a
triggering problem because the signal is a bit irregular (pic here:
http://1drv.ms/1a39ymO), the other two FETs have similarly shaped outputs
but do not wobble in the same way. I wonder if replacing that FET might do
the trick? Or is the inverter the problem as the inputs are perfectly
square?
10:40 p.m.
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 05 April 2015 17:55
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/05/2015 02:55 AM, Robert Jarratt wrote:
>
>> -----Original Message-----
>> From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon
>> Elson
>> Sent: 04 April 2015 22:18
>> To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
>> Subject: Re: RD54 Stopped Spinning
>>
>> On 04/04/2015 04:06 PM, Robert Jarratt wrote:
>>> So when I fired it up again with the scope, the disk started to spin.
>>> This was a stroke of luck as I was able to probe what I believe were
>>> the outputs of the hall sensors. All three oscillated, but one of
>>> them showed significant sideways wobble on the scope, which suggests
>>> to me that the signal is not absolutely regular. It does seem to
>>> suggest that one of the sensors is not working well. However, would
>>> this be enough to explain why it stopped dead in its tracks when it
>>> was working before?
>> Yes, the logic is generally that you decode 6 legal states of the
>> Hall
> sensors to
>> decide which of the 3 motor terminals to drive high and low. if the
>> Hall
> sensors
>> give a signal that has all 3 high, or all 3 low, the decode logic
>> will
> fail, generally
>> leaving all transistors off. If it gets in that state again, a
>> vigorous
> twist of the
>> drive around the spindle axis might shift the rotor to a position
>> where it
> will
>> start up again.
>>> Changing one of these sensors is probably going to be beyond me :-(
>>> Thanks Rob
>> I'd get the data off it quickly and retire the drive. You may only
>> have a
> few
>> minutes run time before the sensors go more flaky and the drive shuts
off.
> But,
>> now that you know the secret, you ought to be able to recover data,
>> if
> that is
>> the plan.
>>
>> Anyway, it seems you have completely diagnosed the problem.
>>
>> Jon
> I checked again this morning, because something was bothering me. I
> realised that the pins I was observing with the scope were the D pins
> on the FETs and not the hall effect sensor outputs. When I went back
> to measure the sensor output properly the outputs looked fine and
> perfectly stable. The outputs from the Z8 also looked fine. The
> outputs of the inverters into the FETs looked stable, although not
square
(pics
here: http://1drv.ms/1a39cwz here:
> http://1drv.ms/1a39kfs and here: http://1drv.ms/1a39pju). It is only
> the output of one of the FETs that looks a bit unstable, but that
> could be a triggering problem because the signal is a bit irregular (pic
here:
http://1drv.ms/1a39ymO), the other two FETs have similarly shaped
outputs but do not wobble in the same way. I wonder if replacing that
FET might do the trick? Or is the inverter the problem as the inputs
are perfectly square?
Do the gate signals not have the wobble? (Wobble could be the PWM of the
speed control logic, so could be normal.) If so, then the FET may be bad. fact, the FET may be entirely OPEN, and the waveform
you see is coming
from
the other two driven phases.
Kind of strange that one gate signal is a smooth ramp, the others have
some
wave on the top.
But, the drive probably has a current sense resistor in the common source
leg
of the low-side transistors, so that is feeding some
of the current
waveform
back to the gates. So, it may well be the one with
the linear ramp on the
top
indicates the drain is open.
Jon
I tested each FET using a component tester (Peak DCA55) and it appeared to
show that they were all good. I believe they are FETs because the XT-1140
schematic someone posted shows FETs and the component tester also reported
them as FETs. I do wonder if one of them is only partially working, I seem
to remember that the one you point out as having smooth ramp was indeed the
one with the wobble. If I have further trouble I will follow Tony's
suggestion and swap them around to see if the wobble moves, but detaching
them from the heat-sink looks to be difficult.
Regards
Rob
6 Apr
6 Apr
1:48 a.m.
On 04/05/2015 04:40 PM, Robert Jarratt wrote:
I tested each FET using a component tester (Peak
DCA55)
and it appeared to show that they were all good. I believe
they are FETs because the XT-1140 schematic someone posted
shows FETs and the component tester also reported them as
FETs. I do wonder if one of them is only partially
working, I seem to remember that the one you point out as
having smooth ramp was indeed the one with the wobble. If
I have further trouble I will follow Tony's suggestion and
swap them around to see if the wobble moves, but detaching
them from the heat-sink looks to be difficult. Regards Rob
I'd just get some
FETs that are compatible (probably MUCH
better parts available today) and replace any suspect ones
with new units. Are these pop-riveted to the heat sink? I
vaguely remember a drive built like that.
Jon
7:05 a.m.
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 06 April 2015 01:48
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/05/2015 04:40 PM, Robert Jarratt wrote:
pop-
I tested each FET using a component tester (Peak
DCA55) and it
appeared to show that they were all good. I believe they are FETs
because the XT-1140 schematic someone posted shows FETs and the
component tester also reported them as FETs. I do wonder if one of
them is only partially working, I seem to remember that the one you
point out as having smooth ramp was indeed the one with the wobble. If
I have further trouble I will follow Tony's suggestion and swap them
around to see if the wobble moves, but detaching them from the
heat-sink looks to be difficult. Regards Rob
I'd just get some FETs that are
compatible (probably MUCH better parts
available today) and replace any suspect ones with new units. Are these riveted to the heat sink? I vaguely remember a drive
built like that.
Jon
I might do what you suggest. They are IRF521 N-Channel and IRF9521 P-Channel
parts, I'll have to find equivalents. Not knowing too much about the
significance of the main parameters, I am not sure how critical the
equivalence needs to be. For example it appears that the IRF521 has
Vdss=60V, Rds(on)=0.3ohm, Id=5A-8A (temperature dependent), while a
similarly numbered modern part I found (IRF540Z) has Vdss=100V,
Rds(on)=0.0265ohm, Id=36A .
The heat sink is not riveted on, but appears to be glued on. I have not
really tried to remove it yet; to test the parts I removed all 6 of them
(the heatsink is a single one across all 6 parts).
Regards
Rob
9:15 a.m.
The heat sink is not riveted on, but appears to be glued on. I have not
really tried to remove it yet; to test the parts I removed all 6 of them
(the heatsink is a single one across all 6 parts).
Perhaps the FETs could be wired back into different locations for test purposes
using extension leads without having to detach them from the heatsink?
Regards,
Peter Coghlan.
4:41 p.m.
On 04/06/2015 01:05 AM, Robert Jarratt wrote:
There will have to be some electrical insulation as the
drains of the low-side transistors can't be commoned.
Make sure you select a transistor with equivalent threshold
voltage (the gate voltage where it starts to turn on).
Jon
-----Original
Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 06 April 2015 01:48
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic Posts
Subject: Re: RD54 Stopped Spinning
On 04/05/2015 04:40 PM, Robert Jarratt wrote:
pop-
I tested each FET using a component tester (Peak
DCA55) and it
appeared to show that they were all good. I believe they are FETs
because the XT-1140 schematic someone posted shows FETs and the
component tester also reported them as FETs. I do wonder if one of
them is only partially working, I seem to remember that the one you
point out as having smooth ramp was indeed the one with the wobble. If
I have further trouble I will follow Tony's suggestion and swap them
around to see if the wobble moves, but detaching them from the
heat-sink looks to be difficult. Regards Rob
I'd just get some FETs that are
compatible (probably MUCH better parts
available today) and replace any suspect ones with new units. Are these riveted to the heat sink? I vaguely remember a
drive built like that.
Jon
I might do what you suggest. They are IRF521 N-Channel and IRF9521 P-Channel
parts, I'll have to find equivalents. Not knowing too much about the
significance of the main parameters, I am not sure how critical the
equivalence needs to be. For example it appears that the IRF521 has
Vdss=60V, Rds(on)=0.3ohm, Id=5A-8A (temperature dependent), while a
similarly numbered modern part I found (IRF540Z) has Vdss=100V,
Rds(on)=0.0265ohm, Id=36A .
The heat sink is not riveted on, but appears to be glued on. I have not
really tried to remove it yet; to test the parts I removed all 6 of them
(the heatsink is a single one across all 6 parts).
3333
days inactive
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