I have an old Heidenhain VRZ 731 2 axis DRO on my BP and the x axis
stopped working. So after determining that it was a sensor assembly
malfunction by switching the x and y sensors into the readout, I
proceed to open the assembly. The etched glass scale is intact so I
explore the actual sensor. It has some photo-cells a lens/collimator and
( I assume) some form of creating a light beam. I find Heidenhain's
website, and luckily a PDF of the manual for my unit. The only thing of
value in the manual is a pinout, a description of what voltages are to
be found on what pins. 2 of the pins are labeled lamp and carry a 5v DC
at 120 milliamps. So now I trace the circuitry and find a direct
connection to what looks like a grain of wheat incandescent lamp
positioned in a subframe assembly. I rule out a LED, because of the 5v
at 120 mA and no current limiting resistor in the circuit. So I start
making calls and finally get the Heidenhain tech in NY. I ask him if he
can repair my sensor. He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 . I ask him if he knows what
the light is on my unit, he says it's a very special lamp, I ask him " a
5v grain of wheat microlamp?" He says it's a very special lamp and no,
they don't have a replacement, and I should buy the new sensor for 600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old
lamp taking care to measure where the original filaments where placed,
and superglue in my new lamp in the same position. A little bit of
soldering and pronto I power up the sensor, adjust the collimator so the
beam of light is perfectly centered on the photocells, replace the unit
into the scale and my x axis now works. A very special lamp indeed!

cheers
T.Alan

I have an old Heidenhain VRZ 731 2 axis DRO on my BP and the x axis
stopped working. So after determining that it was a sensor assembly
malfunction by switching the x and y sensors into the readout, I
proceed to open the assembly. The etched glass scale is intact so I
explore the actual sensor. It has some photo-cells a lens/collimator and
( I assume) some form of creating a light beam. I find Heidenhain's
website, and luckily a PDF of the manual for my unit. The only thing of
value in the manual is a pinout, a description of what voltages are to
be found on what pins. 2 of the pins are labeled lamp and carry a 5v DC
at 120 milliamps. So now I trace the circuitry and find a direct
connection to what looks like a grain of wheat incandescent lamp
positioned in a subframe assembly. I rule out a LED, because of the 5v
at 120 mA and no current limiting resistor in the circuit. So I start
making calls and finally get the Heidenhain tech in NY. I ask him if he
can repair my sensor. He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 . I ask him if he knows what
the light is on my unit, he says it's a very special lamp, I ask him " a
5v grain of wheat microlamp?" He says it's a very special lamp and no,
they don't have a replacement, and I should buy the new sensor for 600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old
lamp taking care to measure where the original filaments where placed,
and superglue in my new lamp in the same position. A little bit of
soldering and pronto I power up the sensor, adjust the collimator so the
beam of light is perfectly centered on the photocells, replace the unit
into the scale and my x axis now works. A very special lamp indeed!

cheers
T.Alan
GOOD ON YA, Alan. I'm always glad to hear of someone actually
FIXING something rather than replacing.....
Ken.

T.Alan Kraus wrote:
I have an old Heidenhain VRZ 731 2 axis DRO on my BP and the x axis
stopped working. So after determining that it was a sensor assembly
malfunction by switching the x and y sensors into the readout, I
proceed to open the assembly. The etched glass scale is intact so I
explore the actual sensor. It has some photo-cells a lens/collimator and
( I assume) some form of creating a light beam. I find Heidenhain's
website, and luckily a PDF of the manual for my unit. The only thing of
value in the manual is a pinout, a description of what voltages are to
be found on what pins. 2 of the pins are labeled lamp and carry a 5v DC
at 120 milliamps. So now I trace the circuitry and find a direct
connection to what looks like a grain of wheat incandescent lamp
positioned in a subframe assembly. I rule out a LED, because of the 5v
at 120 mA and no current limiting resistor in the circuit. So I start
making calls and finally get the Heidenhain tech in NY. I ask him if he
can repair my sensor. He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 . I ask him if he knows what
the light is on my unit, he says it's a very special lamp, I ask him " a
5v grain of wheat microlamp?" He says it's a very special lamp and no,
they don't have a replacement, and I should buy the new sensor for 600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old
lamp taking care to measure where the original filaments where placed,
and superglue in my new lamp in the same position. A little bit of
soldering and pronto I power up the sensor, adjust the collimator so the
beam of light is perfectly centered on the photocells, replace the unit
into the scale and my x axis now works. A very special lamp indeed!

cheers
T.Alan
That superglue could cause a problem in 30 or 40 years when this bulb
burns out.

"wwsjr" wrote in message
. net...
T.Alan Kraus wrote:
I have an old Heidenhain VRZ 731 2 axis DRO on my BP and the x axis
stopped working. So after determining that it was a sensor assembly
malfunction by switching the x and y sensors into the readout, I proceed
to open the assembly. The etched glass scale is intact so I explore the
actual sensor. It has some photo-cells a lens/collimator and ( I assume)
some form of creating a light beam. I find Heidenhain's website, and
luckily a PDF of the manual for my unit. The only thing of value in the
manual is a pinout, a description of what voltages are to be found on
what pins. 2 of the pins are labeled lamp and carry a 5v DC at 120
milliamps. So now I trace the circuitry and find a direct connection to
what looks like a grain of wheat incandescent lamp positioned in a
subframe assembly. I rule out a LED, because of the 5v at 120 mA and no
current limiting resistor in the circuit. So I start making calls and
finally get the Heidenhain tech in NY. I ask him if he can repair my
sensor. He says it's too old, not supported and I might be well served
with a newer model for $ 600.00 . I ask him if he knows what the light is
on my unit, he says it's a very special lamp, I ask him " a 5v grain of
wheat microlamp?" He says it's a very special lamp and no, they don't
have a replacement, and I should buy the new sensor for 600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old
lamp taking care to measure where the original filaments where placed,
and superglue in my new lamp in the same position. A little bit of
soldering and pronto I power up the sensor, adjust the collimator so the
beam of light is perfectly centered on the photocells, replace the unit
into the scale and my x axis now works. A very special lamp indeed!

cheers
T.Alan
That superglue could cause a problem in 30 or 40 years when this bulb
burns out.

Outstanding, Alan. It wasn't as involved as your repair, but I fumed at
paying GM 80 something dollars for an idler pulley on son's Olds. Bearing
was shot. Chucked it up in the lathe, removed the extruded plastic
retainer, put in a high temp bearing from the local motor shop. Resealed it
with epoxy. $11.00 total outlay and my worlthless labor. And I was just as
proud of it as you are your intricate repair.

Garrett Fulton

Great job T.Alan.

I will proceed with my repairs of a dead sensor.

Same type as yours, for a three axis Sargon DRO. I purchased it with a dead
Y axis but figured I could swap the good Z sensor over to the Y rail and
have at least a two axis DRO. This I have done.

I see all the components, just as you describe.

Now, I would appreciate some ID or more descriptive info on this "Grain of
Wheat" lamp. Something I can speak when this plumber walks into the elex
parts store. (I have done electronic repairs before but never anything on
the Micro-Miniature scale.)

BTW. I discovered a trick for getting the encoder sensor back into the rail
and on the glass rod. A popsicle stick shoved into the tail end of the
sensor carriage. Then, once the carriage is started squarely on the rod, I
pull the stick out and use it to put the sensor the rest of the way in.

Appreciate any info you want to share about this component number.

Thanks.

Steve
"T.Alan Kraus" wrote in message
...
I have an old Heidenhain VRZ 731 2 axis DRO on my BP and the x axis stopped
working. So after determining that it was a sensor assembly malfunction by
switching the x and y sensors into the readout, I proceed to open the
assembly. The etched glass scale is intact so I explore the actual sensor.
It has some photo-cells a lens/collimator and ( I assume) some form of
creating a light beam. I find Heidenhain's website, and luckily a PDF of
the manual for my unit. The only thing of value in the manual is a pinout,
a description of what voltages are to be found on what pins. 2 of the pins
are labeled lamp and carry a 5v DC at 120 milliamps. So now I trace the
circuitry and find a direct connection to what looks like a grain of wheat
incandescent lamp positioned in a subframe assembly. I rule out a LED,
because of the 5v at 120 mA and no current limiting resistor in the
circuit. So I start making calls and finally get the Heidenhain tech in NY.
I ask him if he can repair my sensor. He says it's too old, not supported
and I might be well served with a newer model for $ 600.00 . I ask him if
he knows what the light is on my unit, he says it's a very special lamp, I
ask him " a 5v grain of wheat microlamp?" He says it's a very special lamp
and no, they don't have a replacement, and I should buy the new sensor for
600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old lamp
taking care to measure where the original filaments where placed, and
superglue in my new lamp in the same position. A little bit of soldering
and pronto I power up the sensor, adjust the collimator so the beam of
light is perfectly centered on the photocells, replace the unit into the
scale and my x axis now works. A very special lamp indeed!

cheers
T.Alan

Nothing is more satisfying than fixing that which ' can't ' be fixed!

-Dave

I got mine from a place that has bins of stuff, some well labeled some
not. This lamp came from one that was labeled 5v / 60mA. I found the
same in the Mouser catalog (800 346-6873) listed as a type 6833 (catalog
# 606-CM6833).

cheers
T.Alan

Steve wrote:
Great job T.Alan.

I will proceed with my repairs of a dead sensor.

Same type as yours, for a three axis Sargon DRO. I purchased it with a dead
Y axis but figured I could swap the good Z sensor over to the Y rail and
have at least a two axis DRO. This I have done.

I see all the components, just as you describe.

Now, I would appreciate some ID or more descriptive info on this "Grain of
Wheat" lamp. Something I can speak when this plumber walks into the elex
parts store. (I have done electronic repairs before but never anything on
the Micro-Miniature scale.)

BTW. I discovered a trick for getting the encoder sensor back into the rail
and on the glass rod. A popsicle stick shoved into the tail end of the
sensor carriage. Then, once the carriage is started squarely on the rod, I
pull the stick out and use it to put the sensor the rest of the way in.

Appreciate any info you want to share about this component number.

Thanks.

Steve

On Thu, 26 Jan 2006 07:34:14 -0800, "Steve" wrote:

Now, I would appreciate some ID or more descriptive info on this "Grain of
Wheat" lamp. Something I can speak when this plumber walks into the elex
parts store. (I have done electronic repairs before but never anything on
the Micro-Miniature scale.)

Those bulbs are sometimes used in model kits (cars, planes, etc..),
try checking with a local hobby shop.

On Thu, 26 Jan 2006 00:48:52 -0800, "T.Alan Kraus"
wrote:

He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 .

Well done! May the arrogant tech be soon replaced with a newer model!

Steve wrote:

Great job T.Alan.

I will proceed with my repairs of a dead sensor.

Same type as yours, for a three axis Sargon DRO. I purchased it with a dead
Y axis but figured I could swap the good Z sensor over to the Y rail and
have at least a two axis DRO. This I have done.

I see all the components, just as you describe.

Now, I would appreciate some ID or more descriptive info on this "Grain of
Wheat" lamp. Something I can speak when this plumber walks into the elex
parts store. (I have done electronic repairs before but never anything on
the Micro-Miniature scale.)



A grain of wheat bulb is a tiny glass capsule which (once) had a filament in
it. It is probably blackened inside the glass from the vaporized Tungsten.
It will have two tiny copper wires coming out of it. When I say tiny, I
mean
something like .1" diameter and maybe .3" long at the most.

I would replace these with an infrared LED and a series resistor calculated
to draw the proper current for the LED. You may not even need to run
full rated current on modern IR LEDs, as they produce so much output.
The LED won't burn out again.

Jon

I'll bet you could have used a white LED and dropping resistor.
It would use less current than the grain of wheat lamp and last
forever.

T.Alan Kraus wrote:
I rule out a LED, because of the 5v
at 120 mA and no current limiting resistor in the circuit. So I start
making calls and finally get the Heidenhain tech in NY. I ask him if he
can repair my sensor. He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 . I ask him if he knows what
the light is on my unit, he says it's a very special lamp, I ask him " a
5v grain of wheat microlamp?" He says it's a very special lamp and no,
they don't have a replacement, and I should buy the new sensor for 600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old
lamp taking care to measure where the original filaments where placed,
and superglue in my new lamp in the same position.

Don Foreman wrote:

Well done! May the arrogant tech be soon replaced with a newer model!

With a cheap Chinese clone of a Polski farmer?


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

"T.Alan Kraus" wrote
-Snip-

making calls and finally get the Heidenhain tech in NY. I ask him if he
can repair my sensor. He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 . I ask him if he knows what
the light is on my unit, he says it's a very special lamp, I ask him " a
5v grain of wheat microlamp?" He says it's a very special lamp and no,
they don't have a replacement, and I should buy the new sensor for 600$.
I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house,

You should have bought two lamps. One to send to the techie with a note to
place it where the sun don't shine. Very special lamp. Good job.
Tom

According to T.Alan Kraus :
I have an old Heidenhain VRZ 731 2 axis DRO on my BP and the x axis
stopped working.

[ ... ]

explore the actual sensor. It has some photo-cells a lens/collimator and
( I assume) some form of creating a light beam. I find Heidenhain's
website, and luckily a PDF of the manual for my unit. The only thing of
value in the manual is a pinout, a description of what voltages are to
be found on what pins. 2 of the pins are labeled lamp and carry a 5v DC
at 120 milliamps. So now I trace the circuitry and find a direct
connection to what looks like a grain of wheat incandescent lamp
positioned in a subframe assembly. I rule out a LED, because of the 5v
at 120 mA and no current limiting resistor in the circuit.

I suspect that you could put a white-light LED into it just as
well. Add a limiting resistor and you now draw less current, and have a
light source which will not be subjet to failure when operated in the
presence of vibration. (You may need to adjust the current through the
LED to get the right level of illumination to minimize errors.) The
real question is whether you have room for that resistor.

It would probably work well with a red LED for that matter. I
suspect that they were running a 6V grain-of-wheat lamp at 5V to get
longer life from it, so it would be a bit redder than usual.

So I start
making calls and finally get the Heidenhain tech in NY. I ask him if he
can repair my sensor. He says it's too old, not supported and I might be
well served with a newer model for $ 600.00 . I ask him if he knows what
the light is on my unit, he says it's a very special lamp, I ask him " a
5v grain of wheat microlamp?" He says it's a very special lamp and no,
they don't have a replacement, and I should buy the new sensor for 600$.

:-)

I thank him and hang up. So I find a 5v grain of wheat lamp in my local
electronics supply house, take apart the sub-assembly, remove the old
lamp taking care to measure where the original filaments where placed,
and superglue in my new lamp in the same position. A little bit of
soldering and pronto I power up the sensor, adjust the collimator so the
beam of light is perfectly centered on the photocells, replace the unit
into the scale and my x axis now works. A very special lamp indeed!

Of *course* it is very special. *He* doesn't even know where to
get one, so it *must* be special. :-)

Congratulations,
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 ---

wrote:
Nothing is more satisfying than fixing that which ' can't ' be fixed!

-Dave

There are things which really CAN'T be fixed, or it makes no sense
to fix. This was a case of the manufacturer DIDN'T WANT him to fix
it. They sell a lot of new scales and complete new DROs that
way. And, the average shop owner has no way to dig into something
like a DRO scale and know what is wrong.

Jon

Mike Berger wrote:
I'll bet you could have used a white LED and dropping resistor.
It would use less current than the grain of wheat lamp and last
forever.
No, most likely not. Most of these old DRO scales used
Silicon photodiodes which are mostly IR sensitive. The
white LEDs put out NO IR at all, and the sensors would
be nearly blind to that light. Most of the DRO scales
went to IR LEDs as soon as they came on the market, with
no changes to the rest of the sensing head. Most optical
scales still use IR light sources today.

Jon

Ok, an IR LED then!

Jon Elson wrote:
Mike Berger wrote:

I'll bet you could have used a white LED and dropping resistor.
It would use less current than the grain of wheat lamp and last
forever.

No, most likely not. Most of these old DRO scales used
Silicon photodiodes which are mostly IR sensitive. The
white LEDs put out NO IR at all, and the sensors would
be nearly blind to that light. Most of the DRO scales
went to IR LEDs as soon as they came on the market, with
no changes to the rest of the sensing head. Most optical
scales still use IR light sources today.

Jon

Jon Elson wrote:
Mike Berger wrote:

I'll bet you could have used a white LED and dropping resistor.
It would use less current than the grain of wheat lamp and last
forever.

No, most likely not. Most of these old DRO scales used
Silicon photodiodes which are mostly IR sensitive. The
white LEDs put out NO IR at all, and the sensors would
be nearly blind to that light. Most of the DRO scales
went to IR LEDs as soon as they came on the market, with
no changes to the rest of the sensing head. Most optical
scales still use IR light sources today.

Jon

Thanks, another good fact to stash in my noggin. Now if I could only
find the space...

cheers
T.Alan