Datron 4000 Just finishing up.

[Johnny10]

I am in the process of putting back all the pieces of my repaired Datron 4000.

And I have a couple of questions maybe someone on the forum can help me with.
Primarily two questions:

1: The foam on the back of the front panel has completely deteriorated and needs to be replaced.
Need best ideas for best type to use..
It was about 1/2" wide, self adhesive, maybe 3/8 thick? Couldn't really tell it was a slimy mess.


2. The Front screened panel cover is coming loose in spots.
Need to know which is best adhesive to reapply that won't eat through the brown color weeks after I have finished the repair.

Thanks

[coromonadalix]

You have some door insulating foam bands who could do nicely, and they dont deteriorate over time

For the front film : i would remove or lossen  the 5x banana plugs and try to see if the film could be gently lifted, if not, apply some clear GE sillicone with an syringe and a long needle, and put green paint tape to hold it while it cure. the GE sillicone 30min or 1 hr cure will give a strong hold and accept "thermal movement"

If you used "hard" glue like crazy glue etc,  the film will crack in time,  expanion / compression ..... attack the film surface ... it will became brittle.

[Johnny10]

Upon further examination... an adhesive sheet was used to bind the front panel plastic to the metal substrate.
In these areas both layers are de-laminated.

Sometimes the silkscreen stayed on the adhesive sheet.
When separating the decal area is quite brittle and cracks the ink when lifted.

Silicone hadn't thought of that.

[rf+tech]

Johnny10,

As coromonadalix suggests for the foam replacement, look into adhesive-backed foam weather strip. Available in different widths and thicknesses, from your local big box store.

Frost King poly:
https://www.frostking.com/products/weatherstripping/poly-foam-weather-seal-1-year-guarantee

Frost King vinyl:
https://www.frostking.com/products/weatherstripping/vinyl-foam-weatherseal-3-year-guarantee] [url]https://www.frostking.com/products/weatherstripping/vinyl-foam-weatherseal-3-year-guarantee[/url]

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As for the loose front panel skin, the original adhesive is most likely to be non-solvent-based acrylic transfer adhesive. Given that the skin is now stretched, the application of heat and clamping pressure will be required to flatten the skin and hopefully reactivate the adhesive.

My suggestion would be to obtain two pieces of aluminum (or steel) of at least 1/4” thickness, with length and width suitable to cover the lifted area. Pre-heat the panel, heat the metal pieces higher still, place one piece on top and the other behind, apply clamps. Allow to cool to room temperature before removing clamps.

The obvious question is “how hot?” and the answer depends on the type of plastic. Compare the feel of the skin to various plastics. My guess would be one of the polys - polypropylene or polyethylene.

For PP, melting point varies from 130°C to 171°C. For PE, the melting point varies anywhere from 85°C to 145°C. This variation is bound to the degree of polymerization used in the manufacturing process.

Thicker backup plates will afford greater thermal storage mass, thus holding the skin at temperature longer and allowing the molecular bonds more time to relax. How close to the melting point will require some experimentation, obviously starting from the low end.

If the skin is indeed PE or PP, glues are not an option. The waxy/oily feel of PP and PE interferes with adhesion. According to 3M, acrylic adhesives are the go-to for hard to bond materials.

See this 3M document for applications of their 300LSE acrylic adhesive:
http://multimedia.3m.com/mws/media/1371387O/3m-high-strength-acrylic-adhesive-300lse.pdf

300LSE is incredibly tenacious stuff, unlike any off-the-shelf double-sided tape.

RF+ Tech

[Johnny10]

I was just reading an article on that 3M 300SLE

It was like you were reading my mind.
Now I just wish I had one of those photo platen type dry mount press with adjustable temperature control, wouldn't that be perfect?

[coromonadalix]

Maybe an complete front plastic foil makeover could do, did i see a tear on the platic near the windows cut ?

I saw some people drawn a new prototype sheet and got it printed on plastic facia ??  dont know the cost of that operation ..

[Johnny10]

I bought a bunch of Datron 1062 LS101 DMM's for displays and repairing, that was a damaged front panel I can experiment on.

The Datron 4000 front panel is in very good shape but as you said needs to be flattened.