Hi,

I'm replacing the cord on the opthalmoscope illustrated.
http://easthope.ca/HeineBeta200.jpg

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.

On Mon, 6 Aug 2018 08:36:24 -0700 (PDT), Peter Easthope
wrote:

I'm replacing the cord on the opthalmoscope illustrated.
http://easthope.ca/HeineBeta200.jpg

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?

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:
https://www.amazon.com/Gardner-Bender-LTB-400-Electrical-Waterproof/dp/B000FPAN2K
https://plastidip.com
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.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks Jeff.

Yes, the entire black plastic jacket of the cord is crumbling.
It's a coily similar to the cord on an old dial telephone;
cross-section a little smaller. Strain reliefs remain good.

On Monday, August 6, 2018 at 9:44:42 AM UTC-7, Jeff Liebermann wrote:
... 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.

Since it was officially a medical device, unsoldering the
(molded) connectors and replacing just the cord, was not an option.

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.

On Mon, 6 Aug 2018 10:47:03 -0700 (PDT), Peter Easthope
wrote:

Thanks Jeff.

Yes, the entire black plastic jacket of the cord is crumbling.
It's a coily similar to the cord on an old dial telephone;
cross-section a little smaller. Strain reliefs remain good.

On Monday, August 6, 2018 at 9:44:42 AM UTC-7, Jeff Liebermann wrote:
... 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.

Since it was officially a medical device, unsoldering the
(molded) connectors and replacing just the cord, was not an option.

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

On 8/6/2018 11:44 AM, Jeff Liebermann wrote:
On Mon, 6 Aug 2018 08:36:24 -0700 (PDT), Peter Easthope
wrote:

I'm replacing the cord on the opthalmoscope illustrated.
http://easthope.ca/HeineBeta200.jpg

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?

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:
https://www.amazon.com/Gardner-Bender-LTB-400-Electrical-Waterproof/dp/B000FPAN2K

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


https://plastidip.com
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.

On Mon, 6 Aug 2018 10:47:03 -0700 (PDT), Peter Easthope
wrote:

Any further thoughts?

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.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Aug 6 wrote,
Can you get clear heat shrink with the glue inside? If so then the
overlaps would be water tight.

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
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.

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.
https://en.wikipedia.org/wiki/Heat-shrink_tubing
The local retail electronics shops have only one or possibly two
materials. Nothing like the variety described in Wikipedia.

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.

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.

On Tue, 7 Aug 2018 09:24:55 -0700 (PDT), Peter Easthope
wrote:

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.

You can easily get rather flexible polyolefin shrink tubing:
https://www.google.com/search?q=polyolefin+heat+shrink+tubing
https://www.delcity.net/store/Viton-Flexible-Shrink-Tubing/p_818844.h_818845
https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Very-Flexible-Polyolefin-Tubing-VFP-876/?N=5002385+3294230636&rt=rud
It's flexible rubber-like instead of stuff plastic-like.

You can also find "adhesive lined shrink tube":
https://www.google.com/search?q=adhesive+lined+shrink+tube
Looks like there's also "adhesive lined dual wall shrink tube":
https://buyheatshrink.com/heatshrinktubing/

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

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558