Heine Beta 200 opthalmoscope

Hi,

I'm replacing the cord on the opthalmoscope illustrated.

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The strain relief at the bottom of the handle, left in the photo, was released by a pair of clips on a plastic ring. The quick-connect holding the head was locked by a 2.2 mm socket setscrew in the upper thumb ring. Finding a 1.2 mm hex wrench wasn't too difficult.

Now I'm snagged to release the handle from the internal structure. Appears the handle is a tube. In the photo the outer handle should release to the left; inner part to the right. What holds these together?

Thanks, ... Peter E.

Reply to
Peter Easthope
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If all that's wrong is the jacket or strain relief on the cord is broken, perhaps it might be easier to repair the cord? You can get liquid vinyl and liquid rubber at the hardware store, as liquid electrical tape: I've used both on various flexible cords with generally good results. Much depends on how much they are flexed. Neither vinyl nor rubber will tolerate much in the way of radical bending.

The highlight of my cord repairs was for a massage therapist. The cord to some kind of vibration/heat machine head fell apart when the new and improved massage oil she was using caused the rubber cord to crumble and fall apart in large chunks. The maker of the devices wanted $250 to replace the cord and head. Since it was officially a medical device, unsoldering the (molded) connectors and replacing just the cord, was not an option. So, I broke off the remaining crumbling rubber, dipped the cord in thinned liquid vinyl, and hung it vertically to dry. I think it took 4 thin coatings to get it right. Where were plenty of drip marks, but those could be tolerated.

I've also done similar repairs to crumbling Motorola microphone cords, power extension cords, and various molded connectors.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Thanks Jeff.

Yes, the entire black plastic jacket of the cord is crumbl> ... repair the cord? ... liquid electrical tape ...

Interesting idea. There is a can on the shelf here. Uncoiled the cord will be about 3-4 m long. Applying several coats of liquid, neatly, could take some hours.

Your description reminds me that I've built a cord using heat shrink threaded over the end of a bundle of insulated wires. Three or 4 lengths of heat shrink with overlaps of a few inches. The clear heat-shrink remains reasonably pliable after shrinking.

I have opthalmoscopes donated for use in the 3rd world. About a half dozen of them have crumbling cord jackets. No clinic in an industrialized country would accept the heat-shrink repair but a hospital lacking beds for all patients won't complain about an opthalmoscope cord which doesn't coil. And the clear heat shrink allows inspection for a broken wire. The cord hangs against the wall in a U shaped loop with power box at one end and scope at the other. If the heat shrinks are applied from the middle out toward each end, any liquid contamination will shed off. Aside from that, overlaps are tight and I don't visualize anything getting in.

Any further thoughts?

Thanks, ... Peter E.

Reply to
Peter Easthope

Can you get clear heat shrink with the glue inside? If so then the overlaps would be water tight. Eric

Reply to
etpm

I have 100ft 12/3 extension cord that had about a 1 inch x 1/4" section of the outer insulation missing, so the previous owner threw it out. There was no damage to the internal insulation or wire. Of course I picked it up and used the above product or something very similar to effect a beautiful repair. That's been over twenty years ago and it still looks good. My only complaint about the extension cord. it's heavy! :-)

On another subject, I had a medical product go bad while in use on me. It was an electrical stimulator for an acupuncturists needles. It was humming along going from low stimulation up to high and then it would drop and start again. Suddenly it went to high and stayed there! Hey, somebody help me! Doc came in and unhooked me. Next appointment I ask where it was, he said he threw it away! :-) I was was going to try to get it and try "LearnByDestoring" :-) Mikek

Reply to
amdx

In my limited experience, if the cord is starting to crumble, it will continue to crumble. If that's the case with your cord, you may find that you'll need to replace the entire jacket. I don't think that hiding the mess under a shrink tube jacket will suffice. If the rubber cord jacket cracks in some random place, the shrink tube outer jacket will be expected to handle the entire load, and probably stretch, tear, of slide apart if spliced. If possible, cut off the connectors and replace the entire cord.

The problem with the liquid vinyl and liquid rubber approach is that the cord really looks awful with lumps and drip marks. Getting 3-4 meters of the stuff to look good will be difficult and require some practice. The cord I was dealing with was about 2.5 meters long. I was able to suspend it by a hook from the roof (outside), and literally paint the liquid vinyl coating over the cord. As soon as one layer was dry and fairly hard, I would apply the next coat. I tried to fix the drip marks, but only while the coating was still fluid.

I don't know how much time you have to deliver, but I would try the PastiDip first on some other similar cord. If that fails, then methinks the clear shrink tube is a good 2nd best.

One nice feature of any of these methods is that the cord will likely be so ugly, that nobody would consider stealing the instrument from the hospital.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Aug 6 snipped-for-privacy@whidbey.com wrote,

Thanks. I didn't know such a product exists. The cable won't be submerged. If the shrink is sized properly the overlaps should be tight. Incursion of contaminant shouldn't be a problem. Will see how the first repair turns out.

Aug 6 Jeff Liebermann

I aim to break off the entire crumbling jacket before enclosing the wires in the heat shrink. At the ends, two layers of shrink might be necessary to fill the strain relief. For durability, two layers can be applied on the entire cord but that will make it stiffer. Eventually heat shrink will deteriorate but it seems to survive better than ordinary vinyl jacketing. Pertinent information here.

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The local retail electronics shops have only one or possibly two materials. Nothing like the variety described in Wikipedia.

I've heard of copper plumbing being stolen in Accra. Will ask friends whether they've ever encountered theft of instrumentation. FWIIW, most people are honest unless they are starving. A Starbow airline staff refused a tip after retrieving a forgotten tablet.

Thanks for the feedback. Will try a repair and report the results.

... P.

Reply to
Peter Easthope

You can easily get rather flexible polyolefin shrink tubing: It's flexible rubber-like instead of stuff plastic-like.

You can also find "adhesive lined shrink tube": Looks like there's also "adhesive lined dual wall shrink tube":

Unfortunately, I don't have any experience with any of the aforementioned adhesive shrink tube products.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

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