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Proud of myself
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 |
Proud of myself
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. |
Proud of myself
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. |
Proud of myself
"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 |
Proud of myself
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 |
Proud of myself
Nothing is more satisfying than fixing that which ' can't ' be fixed!
-Dave |
Proud of myself
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 |
Proud of myself
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. |
Proud of myself
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! |
Proud of myself
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 |
Proud of myself
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. |
Proud of myself
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 |
Proud of myself
"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 |
Proud of myself
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 --- |
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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 |
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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 |
Proud of myself
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 |
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