Proud of myself

GOOD ON YA, Alan. I'm always glad to hear of someone actually FIXING something rather than replacing..... Ken.

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.

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:

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

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

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

With a cheap Chinese clone of a Polski farmer?

Nick

"T.Alan Kraus" wrote >

-Snip-

making calls and finally get the Heidenhain tech in NY. I ask him if he

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 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.

:-)

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

Congratulations, DoN.

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

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