• Please review our updated Terms and Rules here

CRT Mounting Hardware

M

mattbbx

Member
Joined
Jun 23, 2021
Messages
10
I recently was able to locate and purchase a compatible green CRT for my Model 4 however I am having some fitment issues. The "new" CRT does not have the metal band that wraps around the perimeter of the front of the tube (implosion band?) and thus I have no way of mounting it in my Model 4. I attempted removing the band from my old display however it doesn't seem like it will come off without damaging my original tube. Has anyone fabricated a band for this purpose? How would you install a CRT that doesn't have the necessary mounting band/hardware? Any help is greatly appreciated.

Thank you!
 
I wanted to give my opinion of how I think originals were made and that may help find a solution.

Widespread solution may be needed as I have several new tubes but being stored in a basement damaged these bands with pitting. CRTs are new from 4Ds and they so far have been 100% but MATTBBX has brought up a good question that others will face. I also want to point out that only cases that had CRT disconnected from ground wire were damaged.

When these things came down line at a CRT plant somewhere I think these bands are applied by a machine under pressure, this machine then sealed that band in one piece. Under this band seemed to have been an adhesive with some type fibers (like doing autopsy).

From watching vids on things like YouTube of 1970s TV factories that seems how it was done.

That band and fact its glued and banded tightly with a dab of solder is all that holds or binds the glass tube to metal.

So is this band copper? Or just look copper?

If it is copper how do they become destroyed by moisture? I thought the rich guys whom can afford copper vaults got buried in them because copper doesn't change. Is is because they set with a charge exposed to atmosphere with positive battery post? Its always been a question in my mind..

No matter reason a solution will need to be had.

I suggest using a copper band from craft store or hardware custom trimmed to size of original, a glue or perhaps specialized double sided conductive tape applied then pressed as tight as possible while someone applies a quick bead of solder. Allow to cool before releasing pressure. Mounting posts will need imbedded in band or attached outside. Looks like originals were inside band but it needs further examination. This will also need mounting posts for cabinet and in most cases it looks like old ones are not damaged and can be recycled.

Who wants more new 4D tubes needing TLC? And ones that don't?

I am having a final close out on one x 15 meg original RS, CRT's both in condition above and much better, lots of empty cases, some keyboards, lots of 4Ps in various stages of disassembly, some RS odds and ends and books etc.

I see there is a festival in Ohio this year. I will be unable to attend but willing to meet if your traveling to Ohio near one of our interstates or towns. It must all go to good homes and we do background checks on all customers ;-) Prior convicted TRS80 abusers will disqualify you.

4Ps all have good strong CRTs and PS. Some complete and incomplete cases. Some 4p keyboards.

I just dont want to throw any of this stuff away but I cannot keep these things any longer. Medical issues dictate downsize.

Yes this post is about MATTBBX problem but I own it and helping him with a new tube in addition to helping find how we fix maybe 4 or 5 tube that were in 4D and almost never used.

I know there are lots of modern materials out there that I don't know about that could help find a solution.

But from my radar days I think this needs to be a conductive material that is grounded for proper use and life of tube etc.

So everyone open your TRS80 cases and see what you think solution might be to mount a plain glass tube.

Thank you.
 
The tension bands were usually heated and applied hot. As they cooled, they put the faceplate under tension. Some of the older jugs used a full-metal surround, not a tension band, such as this Clinton one.

Maybe some of the arcade folks might have some suggestions. In any case, support is best done from the faceplate, not the neck (the bulk of the weight is in the faceplate.
 
Many smaller US-made CRTs have an integrated protective faceplate. I don't know about matbbx's jug, however..
Witness the IBM 5151 display, for example.
 
Ah... to shed some more light; MATTBBX screen came from a 4D. Tube has very few hours in it so we want to try to salvage it and many more like them that band has broken.

I have not looked in tech manual to see if it shows any of this mounting hardware in an exploded diagram. Probably asking too much detail for that era of manual but as a whole RS did a very good job documenting.
 
I said ground needed to be around and of tube. I think I am wrong. Ground helps block emissions for FCC but we don't really need worry so much about that on restores.

Here is tubes being made and bands not yet applied but yet they work in testing.

Tube gets warm during use. I bet any method that holds it securely and takes heat over time would work.

https://m.youtube.com/watch?v=5NwMPcYH71g
 
The faceplate looks like it is internal to the tube, the glass is very thick there. I am talking more about the metal band that went around the face of the tube that you would put screws in to mount into a TRS-80 Model 3/4. There are 4 lugs to hold the display on, as well as a grounding strap that goes between two of those points.
 
Has anyone been able to fabricate something? We brainstormed maybe a steel strap from a tension band for shipping materials but I'm afraid of breaking the tube and the implosion horror that follows lol.
 
You can manufacture a mounting band from brass strip around 1 to 1.5 mm thick, perhaps 3/4 to 1" wide (depending on the area available on the CRT) and arrange to tension it with a screw and nut , and fold up and pre solder the mounting ears to it, these are better a little thicker at 1.5 to 2mm. Before attaching it to the CRT, make sure the CRT is coated with good tape where the band will be applied, slightly compressible for the band to bite into a little and grip. Scotch 27 fibreglass tape is suitable. Avoid metal to glass contacts, as the forces are too localized and can crack the glass. Avoid any spring steel bands, harder to work with and require de-Gaussing too.
 
You must log in or register to reply here.
Back
Top