One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I've swapped scales and the problem follows the scale, not the readout
channel.

The scales are Sony p/n SR-2711 and the readout is an LF-200. I
believe they date from around 1985.

I've fixed similar problems in optical encoders, but this is a
Magnescale and most of the circuitry is encapsulated in what appear to
be three mini circuit boards - the long brown devices in the photo. I
haven't been able to make an informed guess as to the function of the
several pots. The optical encoders I've fussed with have one pot for
each channel that tweaks the switching point of a comparator; this is
clearly more complicated.

http://www.suscom-maine.net/~nsimmon...caleHead01.jpg

Before I hook this up to a scope and start fiddling with the pots,
does anyone have or know of an aligment procedure for this unit or any
similar?

--
Ned Simmons

The way I typically approach faults (without service literature) when there
is an identical, known good duplicate item, is to check input/output and
various other circuit points on the good one, making notes for comparison
when checking the faulty one.

The brown boards, as you probably know, are custom circuits, probably long
out of production/NLA.

I'd just naturally suspect the blue tantalum capacitors, just because of
their age.

If I found any obvious abnormalities in the signal comparisons, which is
very likely, I'd likely replace the 6 capacitors after a close inspection of
all the solder connections, as the easiest procedure/age upgrade.

There are a number of silkscreened designations on the board, which is a lot
better than none.

It might be worthwhile to check the feedthrough vias (2 visible) for zero
resistance top/bottom, or just heat them up and fill with solder, and check
all the other soldered connections with a magnifier and reflow any that look
suspicious.

The JAE jumper or the main connector could have some oxidation on the
contacts.

Marking the pot positions clearly before changing them is a good practice.

The cable lead terminals appear to be soldered instead of crimped, but
probably worthwhile to check them.

--
WB
..........


"Ned Simmons" wrote in message
...
One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I've swapped scales and the problem follows the scale, not the readout
channel.

The scales are Sony p/n SR-2711 and the readout is an LF-200. I
believe they date from around 1985.

I've fixed similar problems in optical encoders, but this is a
Magnescale and most of the circuitry is encapsulated in what appear to
be three mini circuit boards - the long brown devices in the photo. I
haven't been able to make an informed guess as to the function of the
several pots. The optical encoders I've fussed with have one pot for
each channel that tweaks the switching point of a comparator; this is
clearly more complicated.

http://www.suscom-maine.net/~nsimmon...caleHead01.jpg

Before I hook this up to a scope and start fiddling with the pots,
does anyone have or know of an aligment procedure for this unit or any
similar?

--
Ned Simmons

On Sun, 21 Feb 2010 19:58:39 -0500, "Wild_Bill"
wrote:

The way I typically approach faults (without service literature) when there
is an identical, known good duplicate item, is to check input/output and
various other circuit points on the good one, making notes for comparison
when checking the faulty one.

The brown boards, as you probably know, are custom circuits, probably long
out of production/NLA.

That's a pretty good bet. And Sony is very stingy with information on
this stuff.


I'd just naturally suspect the blue tantalum capacitors, just because of
their age.

Easy and cheap to replace. How likely is it that 25 year-old tantalums
would be bad? Before the bad channel stopped working entirely it would
sometimes not work properly (though the symptoms were different than
the current problem) until the readout was powered up for a few
minutes, especially if it had not been used for a while. At that point
I was suspicious there might be a bad wet electrolytic cap that was
reforming under power. Can tantalums exhibit the same behavior?


If I found any obvious abnormalities in the signal comparisons, which is
very likely, I'd likely replace the 6 capacitors after a close inspection of
all the solder connections, as the easiest procedure/age upgrade.

There are a number of silkscreened designations on the board, which is a lot
better than none.

Yeah, and at least they are in English, though a bit cryptic.


It might be worthwhile to check the feedthrough vias (2 visible) for zero
resistance top/bottom, or just heat them up and fill with solder, and check
all the other soldered connections with a magnifier and reflow any that look
suspicious.

Again, it'd be easy to reflow all the joints. I'll do that.


The JAE jumper or the main connector could have some oxidation on the
contacts.

I pulled it and reinserted it with no change, but I'll do it a few
more times. All the connectors are gold plated and appear in good
condition, but I know that's no guarantee.

Marking the pot positions clearly before changing them is a good practice.

The cable lead terminals appear to be soldered instead of crimped, but
probably worthwhile to check them.

They're spring connectors on header pins. I've pulled and re-seated
them, but I'll check more thoroughly.

Thanks, Bill.

--
Ned Simmons

On Feb 22, 8:40*am, Ned Simmons wrote:
On Sun, 21 Feb 2010 19:58:39 -0500, "Wild_Bill"

wrote:

I'd just naturally suspect the blue tantalum capacitors, just because of
their age.

Easy and cheap to replace.

Not necessarily cheap, there are wet slug tantalum capacitors for
military/aerospace
use in the range of $30 each. Unless there's a damaged case,
tantalums
fail in short circuit, i.e. if there's voltage across the pins, it's
good.

If it counts UP always, the possibility is that there are two channels
with crosstalk,
in a quadrature counter. Quadrature works by having (for example) a
pair of gear
tooth sensors offset, so if the gear hits sensor 1 first, then sensor
2, you know it's
moving CCW; if it hits sensor 2 first, then sensor 1, it's CW. If
both sensors report
at the same time, direction gets confused but you KNOW it moved. If
there's
a way to clean or reregister the sensors and the scale, I'd start
there. Then
look for wiring common to both sensors (the power supply components in
the sense
head, for instance).

Ned Simmons wrote:
One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I've swapped scales and the problem follows the scale, not the readout
channel.

The scales are Sony p/n SR-2711 and the readout is an LF-200. I
believe they date from around 1985.

Does this have a smooth rod as the scale and a read head with a hole in
it that slides over the rod? If so, the rod is not symmetrical, the
magnetic "whatever it is" is polarized on the side of the rod. So, try
turning the rod in small increments, like 30 degrees, until it starts to
count better. There is a read head floating inside the outer shield
box, and it can get knocked out of alignment and ride crooked on the
rod. There should be a strip of spring steel that can be bent so the
head rides parallel to the rod.

Jon

On 2010-02-21, Ned Simmons wrote:
One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.

[ ... ]

I've fixed similar problems in optical encoders, but this is a
Magnescale and most of the circuitry is encapsulated in what appear to
be three mini circuit boards - the long brown devices in the photo.

Hmm ... if those are what they *look* like, I would expect only
resistors and capacitors under the coating -- mounted on a ceramic
substrate with silk-screened metalization for conductors. And the
coating is fired on, like for a ceramic capacitor, so solid state
devices (transistors, diodes, etc) would not survive the firing
temperatures.

Just how old *is* this thing? The connectors look more modern
than the packaged circuits would suggest.

I
haven't been able to make an informed guess as to the function of the
several pots. The optical encoders I've fussed with have one pot for
each channel that tweaks the switching point of a comparator; this is
clearly more complicated.

http://www.suscom-maine.net/~nsimmon...caleHead01.jpg

Hmm ... it might be that the comparator is at the other end of
the cable, and the circuitry is mostly to match impedance so there is no
reflection of pulses.

Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.
Anyway -- that leaves five signal wires -- two for the 'A' sensor (one
inverted) and two for the 'B' (also one inverted), which produces the
quadrature. That leaves one for the Index (saying that it has reached a
certain reference point on the scale. This matches the five pots, which
probably set amplitudes for each signal fed downstream to the
comparators. Some systems expect to be fed sine waves from the sensors
and use intermediate voltages to interpolate extra resolution.

Before I hook this up to a scope and start fiddling with the pots,
does anyone have or know of an aligment procedure for this unit or any
similar?

That I don't -- sorry.

I would first try checking the waveform from a constant speed
for each of the signals (expecting one of them (the index) to only
change once at an extreme end of the scale.) If any one has a lower
amplitude sine wave than the others, it is suspect. But it might be the
comparators back at the electronics/display box instead.

Good Luck,
Don.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Mon, 22 Feb 2010 14:41:01 -0600, Jon Elson
wrote:

Ned Simmons wrote:
One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I've swapped scales and the problem follows the scale, not the readout
channel.

The scales are Sony p/n SR-2711 and the readout is an LF-200. I
believe they date from around 1985.

Does this have a smooth rod as the scale and a read head with a hole in
it that slides over the rod?

That's the one.

If so, the rod is not symmetrical, the
magnetic "whatever it is" is polarized on the side of the rod. So, try
turning the rod in small increments, like 30 degrees, until it starts to
count better. There is a read head floating inside the outer shield
box, and it can get knocked out of alignment and ride crooked on the
rod. There should be a strip of spring steel that can be bent so the
head rides parallel to the rod.

The scale is very heavily built and has a rather elaborate suspension
system for the rod. It'll take a bit more diassembly to see what's
required to rotate the rod. Thanks for the tip.


--
Ned Simmons

It's been a number of years since I looked up the working principles of
magnetic linear scales, but Jon's recommendations about checking various
mechanical parts' fit/alignment/orientation is likely the best place to
start looking.

The tantalum cap problems I've encountered have been dead shorts, as Whit
commented, and if the current source is sufficient, the outer epoxy layer
may develop a pinhole with smoke shooting out of it (if you happen to be
watching as the power is applied).
Some tantalums seem to just fail abruptly when they get old.

The 3 silvery looking capacitors nearby are poly film types, and if it turns
out that there are signal abnormalities not related to physical/mechanical
parts alignment, it would probably be a good idea to replace the tantalums
and polys just because they're old.
Of course, replacing components can require service/calibration adjustments,
but having the properly working circuit is an advantage.

One other technique that has proved to be worthwhile, is to just rock the
pot positions back 'n forth a little, for a small portion of the rotational
range, after they've been clearly marked for their original positions.
This can sometimes create a better contact, in the event of a bit of
oxidation on the wiper.

If the outcome remains a mystery after making a reasonable amount of
comparisons to the working circuit and scale, the only option may be looking
for a replacement on eBay or surplus places that sell older encoders, linear
scales and similar instrument components. I remember seeing a couple of
surplus websites like that, but that would've been over 5 years ago.

I don't believe there is any way to find out what discrete components are
inside those custom hybrids, without destroying them.

--
WB
..........


"Ned Simmons" wrote in message
...
On Sun, 21 Feb 2010 19:58:39 -0500, "Wild_Bill"
wrote:


The brown boards, as you probably know, are custom circuits, probably long
out of production/NLA.

That's a pretty good bet. And Sony is very stingy with information on
this stuff.


I'd just naturally suspect the blue tantalum capacitors, just because of
their age.

Easy and cheap to replace. How likely is it that 25 year-old tantalums
would be bad? Before the bad channel stopped working entirely it would
sometimes not work properly (though the symptoms were different than
the current problem) until the readout was powered up for a few
minutes, especially if it had not been used for a while. At that point
I was suspicious there might be a bad wet electrolytic cap that was
reforming under power. Can tantalums exhibit the same behavior?



There are a number of silkscreened designations on the board, which is a
lot
better than none.

Yeah, and at least they are in English, though a bit cryptic.


It might be worthwhile to check the feedthrough vias (2 visible) for zero
resistance top/bottom, or just heat them up and fill with solder, and
check
all the other soldered connections with a magnifier and reflow any that
look
suspicious.

Again, it'd be easy to reflow all the joints. I'll do that.


The JAE jumper or the main connector could have some oxidation on the
contacts.

I pulled it and reinserted it with no change, but I'll do it a few
more times. All the connectors are gold plated and appear in good
condition, but I know that's no guarantee.

Marking the pot positions clearly before changing them is a good practice.

The cable lead terminals appear to be soldered instead of crimped, but
probably worthwhile to check them.

They're spring connectors on header pins. I've pulled and re-seated
them, but I'll check more thoroughly.

Thanks, Bill.

--
Ned Simmons

On 23 Feb 2010 02:29:21 GMT, "DoN. Nichols"
wrote:

On 2010-02-21, Ned Simmons wrote:
One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.

[ ... ]

I've fixed similar problems in optical encoders, but this is a
Magnescale and most of the circuitry is encapsulated in what appear to
be three mini circuit boards - the long brown devices in the photo.

Hmm ... if those are what they *look* like, I would expect only
resistors and capacitors under the coating -- mounted on a ceramic
substrate with silk-screened metalization for conductors. And the
coating is fired on, like for a ceramic capacitor, so solid state
devices (transistors, diodes, etc) would not survive the firing
temperatures.

It appears to be an epoxy coating. There are no active components on
the circuit board, and I'm pretty sure there are none in the reader
head, so there must be some in those potted circuits.


Just how old *is* this thing? The connectors look more modern
than the packaged circuits would suggest.

As far as I know, about 1985, maybe as early as 1980.


I
haven't been able to make an informed guess as to the function of the
several pots. The optical encoders I've fussed with have one pot for
each channel that tweaks the switching point of a comparator; this is
clearly more complicated.

http://www.suscom-maine.net/~nsimmon...caleHead01.jpg

Hmm ... it might be that the comparator is at the other end of
the cable, and the circuitry is mostly to match impedance so there is no
reflection of pulses.

I don't think so. I'll know better once I hook it up to a 'scope.


Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.

No LEDs -- Magnescale = magnetic scales.

Anyway -- that leaves five signal wires -- two for the 'A' sensor (one
inverted) and two for the 'B' (also one inverted), which produces the
quadrature. That leaves one for the Index (saying that it has reached a
certain reference point on the scale.

I did find a pinout which indicates that the pickup for each channel
plus the index uses two wires, so all six leads are accounted for.

This matches the five pots, which
probably set amplitudes for each signal fed downstream to the
comparators. Some systems expect to be fed sine waves from the sensors
and use intermediate voltages to interpolate extra resolution.

I'm guessing something similar. Pots to set the gain on amplifiers
that boost the pickup signals, and pots to adjust the comparators.
Though that'd imply six pots -- two per channel.

I did find a patent issued to Sony for a later generation magnetic
scale with circuits. I haven't read it carefully yet, but it appears
there are some clues there.


Before I hook this up to a scope and start fiddling with the pots,
does anyone have or know of an aligment procedure for this unit or any
similar?

That I don't -- sorry.

I would first try checking the waveform from a constant speed
for each of the signals (expecting one of them (the index) to only
change once at an extreme end of the scale.) If any one has a lower
amplitude sine wave than the others, it is suspect. But it might be the
comparators back at the electronics/display box instead.

Good Luck,
Don.

--
Ned Simmons

In article ,
Ned Simmons wrote:

On Mon, 22 Feb 2010 14:41:01 -0600, Jon Elson
wrote:

Ned Simmons wrote:
One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I've swapped scales and the problem follows the scale, not the readout
channel.

The scales are Sony p/n SR-2711 and the readout is an LF-200. I
believe they date from around 1985.

Does this have a smooth rod as the scale and a read head with a hole in
it that slides over the rod?

That's the one.

If so, the rod is not symmetrical, the
magnetic "whatever it is" is polarized on the side of the rod. So, try
turning the rod in small increments, like 30 degrees, until it starts to
count better. There is a read head floating inside the outer shield
box, and it can get knocked out of alignment and ride crooked on the
rod. There should be a strip of spring steel that can be bent so the
head rides parallel to the rod.

The scale is very heavily built and has a rather elaborate suspension
system for the rod. It'll take a bit more diassembly to see what's
required to rotate the rod. Thanks for the tip.

Are there any patent numbers on the scale or reader? Looking up the
patents can be very useful.

Also, Sony may still have data on the scale.

Joe Gwinn

On Tue, 23 Feb 2010 08:13:23 -0500, Joseph Gwinn
wrote:



Are there any patent numbers on the scale or reader? Looking up the
patents can be very useful.

No patent numbers that I can find. But as I mentioned to DoN, I did
find some Sony patents that look to be on point.


Also, Sony may still have data on the scale.

Sony is remarkably stingy even with data on current products. But one
of my customers uses a slew of the Sony tape scales, so I might call
in a favor and see if they can get anything from their distributor.

--
Ned Simmons

Ned Simmons wrote:

One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I'm reading this with a bit of interest. My bridgeport has what I believe are
magnescales. They look old. Blue cold cathode display, some what dim, two joysticks for
zeroing, setting presets. Reads out to 0.0001" which is overkill on a mill.

Does this sound like your scales? Just curious, can't remember what model but I found
squat about it on the web and I'm pretty good at finding things. Not as good as Iggy,
that man is a wizzard from some of the stuff he has drug up.

Part of me wants it to die so I can buy a DRO with features, the other part of me is work
with it, more money in the toy budget.


Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

On Wed, 24 Feb 2010 19:06:40 -0500, Wes wrote:

Ned Simmons wrote:

One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I'm reading this with a bit of interest. My bridgeport has what I believe are
magnescales. They look old. Blue cold cathode display, some what dim, two joysticks for
zeroing, setting presets. Reads out to 0.0001" which is overkill on a mill.

Does this sound like your scales? Just curious, can't remember what model but I found
squat about it on the web and I'm pretty good at finding things. Not as good as Iggy,
that man is a wizzard from some of the stuff he has drug up.

Definitely a different readout. Mine's an LF-200 like these on guess
who's page:
http://yabe.algebra.com/~ichudov/mis...-1464.jpg.html

This is the good scale, still on the grinder:
http://www.suscom-maine.net/~nsimmon...gnescale00.JPG
http://www.suscom-maine.net/~nsimmon...gnescale01.JPG

The pic I posted before is the end of the cable that plugs into the
readout, with its cover removed. I'm not sure that this
interface/connector was the only one used with these particular
scales. There may have been others for use with different readouts.
http://www.suscom-maine.net/~nsimmon...caleHead01.jpg


Part of me wants it to die so I can buy a DRO with features, the other part of me is work
with it, more money in the toy budget.

Weren't you playing with Alibre a while ago? A good CAD package is
much handier than a full featured DRO, IMO. Though a midpoint function
and full keypad is nice.

--
Ned Simmons

Ned Simmons wrote:

On Wed, 24 Feb 2010 19:06:40 -0500, Wes wrote:

Ned Simmons wrote:

One axis on my grinder readout is reading erratically and the symptoms
point to the pulse detection/shaping circuit being out of alignment.
The scale indicates approximately the proper distance travelled, but
only counts in one direction. In other words, move forward 1 inch and
the readout will indicate approximately 1.0000; move back to the
original position and instead of returning to 0.0000 it reads, more or
less, 2.0000.

I'm reading this with a bit of interest. My bridgeport has what I believe are
magnescales. They look old. Blue cold cathode display, some what dim, two joysticks for
zeroing, setting presets. Reads out to 0.0001" which is overkill on a mill.

Does this sound like your scales? Just curious, can't remember what model but I found
squat about it on the web and I'm pretty good at finding things. Not as good as Iggy,
that man is a wizzard from some of the stuff he has drug up.

Definitely a different readout. Mine's an LF-200 like these on guess
who's page:
http://yabe.algebra.com/~ichudov/mis...-1464.jpg.html

Yup. Different but I think I saw that style head on a height gage at work. Not sure it
is still in use.

This is the good scale, still on the grinder:
http://www.suscom-maine.net/~nsimmon...gnescale00.JPG
http://www.suscom-maine.net/~nsimmon...gnescale01.JPG

Mine don't look like that.

The pic I posted before is the end of the cable that plugs into the
readout, with its cover removed. I'm not sure that this
interface/connector was the only one used with these particular
scales. There may have been others for use with different readouts.
http://www.suscom-maine.net/~nsimmon...caleHead01.jpg


Part of me wants it to die so I can buy a DRO with features, the other part of me is work
with it, more money in the toy budget.

Weren't you playing with Alibre a while ago? A good CAD package is
much handier than a full featured DRO, IMO. Though a midpoint function
and full keypad is nice.

I'm still using Alibre. Steep learning curve, my cad exprerience started at Autocad 2.6
and stayed 2d until last year. I plan to upgrade my level at the 1 year point when my
maintenance runs out. Motion, configurations, and sheetmetal could be handy. The
sheetmetal would be handy for projects at work. We turn, mill, have an an Amada cnc
turret press along with an Adira CNC press brake. Pretty sweet having the sheet metal
stuff when you want to make something out of sheet metal for in house use.

Drawing it using autocad, "not so much" as Latka would say.

The thing I crave is multiple origins. The mill at work, that has a much newer Sony scale
system, I indicate the right side of fixed jaw as co-ordinate set 1.

Depending on what I'm making and how many, having a few other origins programed is a time
saver.

Bolt circle, no problem, my palm pda has a program for that.

Wes




--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

DoN. Nichols wrote:

Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.
No, these packaged things look so much like
Sprague parts, made in the
mid-late 60's, just before integrated circuits
took over. The rest of that module DOES look
newer than that, however.

But, the MAGnescale is magnetic, so there would be
no LEDs. It has a smooth
stainless rod with SOMETHING inside. There is an
excitation coil and two pickup coils, so the
signal scheme is exactly like a resolver or
inductosyn. You excite with a sine wave at some
modest frequency like 400 Hz, and as the head is
moved, the signal on each pickup coil rises, falls
and then reverses polarity with respect to the
excitation. The two coils pick up this signal in
quadrature. The converter box interpolates the
signal to increase resolution.

I played with a damaged one of these units at a
shop in Wichita. I got fairly good
signals out of it after repairing some TOTALLY
hair-thin wires in the head, but we never got a
decent signal out of the converter box.

Jon

"Jon Elson" wrote in message
...
DoN. Nichols wrote:

Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.
No, these packaged things look so much like Sprague parts, made in the
mid-late 60's, just before integrated circuits took over. The rest of
that module DOES look newer than that, however.

But, the MAGnescale is magnetic, so there would be no LEDs. It has a
smooth
stainless rod with SOMETHING inside.


I think you'll find that the SOMETHING'S inside are precision ground
bearing balls.

there is a British manufacturer who still makes them like that. They were
fearured in "Model Enginners Workshop"
a year or two ago









There is an
excitation coil and two pickup coils, so the signal scheme is exactly like
a resolver or inductosyn. You excite with a sine wave at some modest
frequency like 400 Hz, and as the head is moved, the signal on each pickup
coil rises, falls and then reverses polarity with respect to the
excitation. The two coils pick up this signal in quadrature. The
converter box interpolates the signal to increase resolution.

I played with a damaged one of these units at a shop in Wichita. I got
fairly good
signals out of it after repairing some TOTALLY hair-thin wires in the
head, but we never got a decent signal out of the converter box.

Jon

Grumpy wrote:
"Jon Elson" wrote in message
...

DoN. Nichols wrote:


Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.

No, these packaged things look so much like Sprague parts, made in the
mid-late 60's, just before integrated circuits took over. The rest of
that module DOES look newer than that, however.

But, the MAGnescale is magnetic, so there would be no LEDs. It has a
smooth
stainless rod with SOMETHING inside.



I think you'll find that the SOMETHING'S inside are precision ground
bearing balls.

there is a British manufacturer who still makes them like that. They were
fearured in "Model Enginners Workshop"
a year or two ago




Newall http://www.newall.co.uk/index.php







There is an

excitation coil and two pickup coils, so the signal scheme is exactly like
a resolver or inductosyn. You excite with a sine wave at some modest
frequency like 400 Hz, and as the head is moved, the signal on each pickup
coil rises, falls and then reverses polarity with respect to the
excitation. The two coils pick up this signal in quadrature. The
converter box interpolates the signal to increase resolution.

I played with a damaged one of these units at a shop in Wichita. I got
fairly good
signals out of it after repairing some TOTALLY hair-thin wires in the
head, but we never got a decent signal out of the converter box.

Jon

In article ,
Jon Elson wrote:

DoN. Nichols wrote:

Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.
No, these packaged things look so much like
Sprague parts, made in the
mid-late 60's, just before integrated circuits
took over. The rest of that module DOES look
newer than that, however.

But, the MAGnescale is magnetic, so there would be
no LEDs. It has a smooth
stainless rod with SOMETHING inside. There is an
excitation coil and two pickup coils, so the
signal scheme is exactly like a resolver or
inductosyn. You excite with a sine wave at some
modest frequency like 400 Hz, and as the head is
moved, the signal on each pickup coil rises, falls
and then reverses polarity with respect to the
excitation. The two coils pick up this signal in
quadrature. The converter box interpolates the
signal to increase resolution.

The patent literature will tell you a lot. Look for patents assigned to "Sony
Magnescale". There are ~30 such patents, some with relevant-sounding titles.

http://www.patentstorm.us/assignee-patents/_Sony_Magnescale_Inc_/44718/1.html

Google Patents is a convenient place to search, but be aware that patent
drawings on google are often mangled. If so, use http://www.pat2pdf.org to
get an unmangled copy.


I don't think that Magnescale and Newell encoders work the same way, even though
both are "magnetic".

Joe Gwinn

"David Billington" wrote in message
...
Grumpy wrote:
"Jon Elson" wrote in message
...

DoN. Nichols wrote:


Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.

No, these packaged things look so much like Sprague parts, made in the
mid-late 60's, just before integrated circuits took over. The rest of
that module DOES look newer than that, however.

But, the MAGnescale is magnetic, so there would be no LEDs. It has a
smooth
stainless rod with SOMETHING inside.



I think you'll find that the SOMETHING'S inside are precision ground
bearing balls.

there is a British manufacturer who still makes them like that. They were
fearured in "Model Enginners Workshop"
a year or two ago




Newall http://www.newall.co.uk/index.php


Yes. that's the one.

replying to Jon Elson, CARLOS REIS wrote:
Hi jon

Did you rewired the coils?
I need to rewire the tiny inside the head but the double excitation coil seems
impossible to do manualy.
Can you help me with some advice?

Thanks
Carlos
Lisbon, Portugal

--
posted from
http://www.polytechforum.com/metalwo...re-225479-.htm

CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Hi jon

Did you rewired the coils?
I need to rewire the tiny inside the head but the double excitation coil
seems impossible to do manualy.
Can you help me with some advice?

Thanks
Carlos
Lisbon, Portugal

Wow, this is from something from a number of years ago. I DID rewire the
coils, and we got pretty good signals going into the converter, but the
output was no good. I don't know if we didn't wire it right, or if the
ferrite was damaged. Anyway, as far as I know, the scale never worked
again. Possibly somebody found a read head surplus and got it working
again.

Jon

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

--
posted from
http://www.polytechforum.com/metalwo...re-225479-.htm

On Thu, 16 Jun 2016 14:18:30 -0500, Jon Elson
wrote:

CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Hi jon

Did you rewired the coils?
I need to rewire the tiny inside the head but the double excitation coil
seems impossible to do manualy.
Can you help me with some advice?

Thanks
Carlos
Lisbon, Portugal

Wow, this is from something from a number of years ago. I DID rewire the
coils, and we got pretty good signals going into the converter, but the
output was no good. I don't know if we didn't wire it right, or if the
ferrite was damaged. Anyway, as far as I know, the scale never worked
again. Possibly somebody found a read head surplus and got it working
again.

Jon

I was the original poster of that thread. And in my case the problem
also turned out to be the read head. I was unable to find a complete
used scale of the proper length, but was able to swap out the head
from another scale. Two things to be aware of when doing this: First,
the scale is calibrated by tensioning the scale rod in the housing,
and you need to remove the rod to swap read heads. I was able to
re-calibrate to my satisfaction with gage blocks and a 50 millionths
test indicator. Second, what appear to be rivets in the housing covers
are actually fillister head machine screws with no slot or other tool
recess. A small drill chuck will grab them and they unscrew easily.

--
Ned Simmons

In article , Ned Simmons
wrote:

On Thu, 16 Jun 2016 14:18:30 -0500, Jon Elson
wrote:

CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Hi jon

Did you rewired the coils?
I need to rewire the tiny inside the head but the double excitation coil
seems impossible to do manualy.
Can you help me with some advice?

Thanks
Carlos
Lisbon, Portugal

Wow, this is from something from a number of years ago. I DID rewire the
coils, and we got pretty good signals going into the converter, but the
output was no good. I don't know if we didn't wire it right, or if the
ferrite was damaged. Anyway, as far as I know, the scale never worked
again. Possibly somebody found a read head surplus and got it working
again.

Jon

I was the original poster of that thread. And in my case the problem
also turned out to be the read head. I was unable to find a complete
used scale of the proper length, but was able to swap out the head
from another scale. Two things to be aware of when doing this: First,
the scale is calibrated by tensioning the scale rod in the housing,
and you need to remove the rod to swap read heads. I was able to
re-calibrate to my satisfaction with gage blocks and a 50 millionths
test indicator. Second, what appear to be rivets in the housing covers
are actually fillister head machine screws with no slot or other tool
recess. A small drill chuck will grab them and they unscrew easily.

The heads are probably slightly oval - I've seen ads from a company
that makes such screws and the matching drivers.

Joe Gwinn

On Fri, 17 Jun 2016 08:57:51 -0400, Joe Gwinn
wrote:

In article , Ned Simmons
wrote:

On Thu, 16 Jun 2016 14:18:30 -0500, Jon Elson
wrote:

CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Hi jon

Did you rewired the coils?
I need to rewire the tiny inside the head but the double excitation coil
seems impossible to do manualy.
Can you help me with some advice?

Thanks
Carlos
Lisbon, Portugal

Wow, this is from something from a number of years ago. I DID rewire the
coils, and we got pretty good signals going into the converter, but the
output was no good. I don't know if we didn't wire it right, or if the
ferrite was damaged. Anyway, as far as I know, the scale never worked
again. Possibly somebody found a read head surplus and got it working
again.

Jon

I was the original poster of that thread. And in my case the problem
also turned out to be the read head. I was unable to find a complete
used scale of the proper length, but was able to swap out the head
from another scale. Two things to be aware of when doing this: First,
the scale is calibrated by tensioning the scale rod in the housing,
and you need to remove the rod to swap read heads. I was able to
re-calibrate to my satisfaction with gage blocks and a 50 millionths
test indicator. Second, what appear to be rivets in the housing covers
are actually fillister head machine screws with no slot or other tool
recess. A small drill chuck will grab them and they unscrew easily.

The heads are probably slightly oval - I've seen ads from a company
that makes such screws and the matching drivers.

Joe Gwinn

Could be, the heads look perfectly round to the naked eye, but measure
about .010 out of round.

--
Ned Simmons

CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom microscope,
and use fine tweezers. I do micro soldering all the time anyway, but this
was something that really tested my skills.

Jon

"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken 1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

replying to Jon Elson, CARLOS REIS wrote:
Working on it right now!

Some pictures to sow the complete mess...

I'm working by fun and trial error because:
I don't know the wire sense of rotation
I don't know what is the channel one or channel two coil
I've simplified the excitation coil because till now I was unable to do it
similar to the original one

So, lets party!
http://www.polytechforum.com/img/51
http://www.polytechforum.com/img/52
http://www.polytechforum.com/img/53
http://www.polytechforum.com/img/54

replying to Jon Elson, CARLOS REIS wrote:

http://www.polytechforum.com/img/55

On Friday, June 17, 2016 at 5:49:22 PM UTC-4, Jim Wilkins wrote:
"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken 1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

I've also done lots of ridiculously small soldering with the aid of a stereo zoo scope, but I've never used conductive epoxy.

Properly cleaned and fluxed, solder will (usually) go where it's supposed to go and (usually) stay out of where it's not supposed to go. How do you handle this with epoxy? If you accidentally get some where it's not supposed to go, can you clean it off?

I could certainly see using conductive epoxy for repairing Kapton flat cables. That stuff is really hard to solder without melting lots of plastic.

On Sat, 18 Jun 2016 08:00:00 -0700 (PDT), rangerssuck
wrote:

On Friday, June 17, 2016 at 5:49:22 PM UTC-4, Jim Wilkins wrote:
"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken 1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

I've also done lots of ridiculously small soldering with the aid of a stereo zoo scope, but I've never used conductive epoxy.

Properly cleaned and fluxed, solder will (usually) go where it's supposed to go and (usually) stay out of where it's not supposed to go. How do you handle this with epoxy? If you accidentally get some where it's not supposed to go, can you clean it off?

I could certainly see using conductive epoxy for repairing Kapton flat cables. That stuff is really hard to solder without melting lots of plastic.

Speaking of conductive plastics, you guys may be interested in a big
push that HP is making into 3D printing (additive manufacturing).
They're embedding conductive-plastic electrical conductors in the 3D
parts. I don't know the market they're shooting for, but my guess is
that it's automotive.

--
Ed Huntress

"rangerssuck" wrote in message
...
On Friday, June 17, 2016 at 5:49:22 PM UTC-4, Jim Wilkins wrote:
"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken
1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

I've also done lots of ridiculously small soldering with the aid of
a stereo zoo scope, but I've never used conductive epoxy.

Properly cleaned and fluxed, solder will (usually) go where it's
supposed to go and (usually) stay out of where it's not supposed to
go. How do you handle this with epoxy? If you accidentally get some
where it's not supposed to go, can you clean it off?

I could certainly see using conductive epoxy for repairing Kapton
flat cables. That stuff is really hard to solder without melting
lots of plastic.

I used conductive epoxy only where I had to. Gold bonding ribbon
dissolves instantly in solder. I soldered temporary isolating cuts in
not-much-larger 6 mil copper traces. It's easier if the cut is skewed
so the beveled ends overlap.

The bonding ribbons were fairly long arches from copper pads to the
laser diode die which was mounted on a diamond substrate. Apparently
the tech at the first government lab that had the project was
incapable of such delicate work, so Mitre got it and I patched his
mistakes. They knew I could stack up 3D assemblies of 0201 resistor
chips. My demo was to join 0.015" solder into linked rings.

--jsw

CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:

http://www.polytechforum.com/img/55
OHHH, MY! That looks like a total mess. Did you rewind the coils? The one
I worked on, the coils were OK, just the connection to the terminal strip
were broken.

Good luck, you are going to need it!

Jon

On Saturday, June 18, 2016 at 11:19:55 AM UTC-4, Ed Huntress wrote:
On Sat, 18 Jun 2016 08:00:00 -0700 (PDT), rangerssuck
wrote:

On Friday, June 17, 2016 at 5:49:22 PM UTC-4, Jim Wilkins wrote:
"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken 1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

I've also done lots of ridiculously small soldering with the aid of a stereo zoo scope, but I've never used conductive epoxy.

Properly cleaned and fluxed, solder will (usually) go where it's supposed to go and (usually) stay out of where it's not supposed to go. How do you handle this with epoxy? If you accidentally get some where it's not supposed to go, can you clean it off?

I could certainly see using conductive epoxy for repairing Kapton flat cables. That stuff is really hard to solder without melting lots of plastic.

Speaking of conductive plastics, you guys may be interested in a big
push that HP is making into 3D printing (additive manufacturing).
They're embedding conductive-plastic electrical conductors in the 3D
parts.

Yeah, at the very least, until 2004 or 2005, I hadn't known that magnetic fields go through non-shielded insulation until I saw another installer on a construction site using a "cable verifier". I think it was made by Fluke. You hold it up to a low voltage wire and the cable verifier's speaker will play the communications out loud that it picks up in the wire (via magnetic field).

On Sat, 18 Jun 2016 15:16:12 -0700 (PDT), wrote:

On Saturday, June 18, 2016 at 11:19:55 AM UTC-4, Ed Huntress wrote:
On Sat, 18 Jun 2016 08:00:00 -0700 (PDT), rangerssuck
wrote:

On Friday, June 17, 2016 at 5:49:22 PM UTC-4, Jim Wilkins wrote:
"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken 1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

I've also done lots of ridiculously small soldering with the aid of a stereo zoo scope, but I've never used conductive epoxy.

Properly cleaned and fluxed, solder will (usually) go where it's supposed to go and (usually) stay out of where it's not supposed to go. How do you handle this with epoxy? If you accidentally get some where it's not supposed to go, can you clean it off?

I could certainly see using conductive epoxy for repairing Kapton flat cables. That stuff is really hard to solder without melting lots of plastic.

Speaking of conductive plastics, you guys may be interested in a big
push that HP is making into 3D printing (additive manufacturing).
They're embedding conductive-plastic electrical conductors in the 3D
parts.

Yeah, at the very least, until 2004 or 2005, I hadn't known that magnetic fields go through non-shielded insulation until I saw another installer on a construction site using a "cable verifier". I think it was made by Fluke. You hold it up to a low voltage wire and the cable verifier's speaker will play the communications out loud that it picks up in the wire (via magnetic field).

Keep in mind that this is not anything going on through insulation.
The conductive plastic conducts current directly. I can be multiple
"wires" embedded in a 3D-printed part or device.

--
Ed Huntress

replying to Jon Elson, CARLOS REIS wrote:
Bad news
I gave up. Couldn't have any readings after trying for a while.

Thanks everyone for help and support

--
posted from
http://www.polytechforum.com/metalwo...re-225479-.htm