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Resetting a Tektronix 4051

I've already ordered a bunch of the M6-0120 keyswitches from the website @nikola-wan mentions. I'm having them shipped to relatives in the USA now and will bring them back to the UK after I visit them in late September. It sounds like we are going to be lousy with keyswitches now, especially since that website has a minimum order amount that requires you to buy somewhat more than 11.

I am fairly certain that even though the 4054 mechanical parts list specifies M6-0100 keyswitches for the keyboard and keypad keys, the keyswitches on the 4054A here are actually M6-0120s. My understanding of the difference is that the -0100 has a flat blade-shaped keystem (as found under the function keys) while the -0120 has T-shaped keystem, which is what I observe.

The switches in my 4051s and in the 4054A have slightly different ways of limiting key travel. The 4051 switches have two plastic "bosses" close to the perimeter of the switch that catch the "rim" of the keycap, while the 4054A switches have a kind of "wall" that surrounds the keystem at the base and catches the "trunk" of the keycap. My guess is that these are probably different revisions of the same -0120 switch.

Anyway, it sounds like I am soon to be the UK M6-0120 king :) Anyone here who has a need of some keyswitches can feel free to drop me a line...
 
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stepleton said:
I've already ordered a bunch of the M6-0120 keyswitches from the website @nikola-wan mentions. I'm having them shipped to relatives in the USA now and will bring them back to the UK after I visit them in late September. It sounds like we are going to be lousy with keyswitches now, especially since that website has a minimum order amount that requires you to buy somewhat more than 11.

I am fairly certain that even though the 4054 mechanical parts list specifies M6-0100 keyswitches for the keyboard and keypad keys, the keyswitches on the 4054A here are actually M6-0120s. My understanding of the difference is that the -0100 has a flat blade-shaped keystem (as found under the function keys) while the -0120 has T-shaped keystem, which is what I observe.

The switches in my 4051s and in the 4054A have slightly different ways of limiting key travel. The 4051 switches have two plastic "bosses" close to the perimeter of the switch that catch the "rim" of the keycap, while the 4054A switches have a kind of "wall" that surrounds the keystem at the base and catches the "trunk" of the keycap. My guess is that these are probably different revisions of the same -0120 switch.

Anyway, it sounds like I am soon to be the UK M6-0120 king :) Anyone here who has a need of some keyswitches can feel free to drop me a line...
Click to expand...

I would love to purchase three switches from you - one to replace my left shift key switch and two for spares. They could be mailed to me when you are picking them up in the USA :biggrin:

I have found the hard way that dropping things on the keyboard will break the keyswitch shafts.

I now cover my 4052 CRT and tape drive opening with a 12-inch x 8.5-inch Alvin GBM0812 rotary cutting board for $9.99: https://www.amazon.com/Alvin-GBM0812-Professional-Self-Healing-Convenient/dp/B00251I5P4

Actually Alvin has a lot of different size cutting boards - this 12"x18" one for $16.67 might be perfect as the 4051/4052 keyboard cover (and could be trimmed down for better fit):
https://www.amazon.com/Alvin-GBM0812-Professional-Self-Healing-Convenient/dp/B0015AOIYI

My 4052 Display protector.jpg

You might notice the Left Shift keycap is laying on top of the broken key switch shaft. Since the break happened at the keycap - I can still 'carefully' use the Left Shift but would like to fix it.
 
I wonder if Cherry MX keycaps would fit the Tektronix 4050 keyboard Cherry M6-0120 key switches? The MX switches have a full "cross" whereas the M6-0120 switches have a "T" but the keycaps have a full cross hole.

I find lots of 3D printed Cherry MX keycap designs on the web.

In particular - Adafruit has posted this set of files on: https://www.thingiverse.com/thing:749563

Even better is the whole Adafruit project - designing keycaps to fit the exact key cap shape and dimensions: https://learn.adafruit.com/3dprinted-custom-keycaps

They recommend resin printing the keycaps.

If you can emboss the label slightly - then fill with paint - I think it could look great!
 
nikola-wan said:
I would love to purchase three switches from you - one to replace my left shift key switch and two for spares. They could be mailed to me when you are picking them up in the USA :biggrin:
Click to expand...
Happy to do that. We can exchange details closer to my travel date.

One other thing I need for one of the 4051s is one of the tall metal "puzzle pieces" that link the space bar to the stabiliser hinge. This should be reasonably straightforward to fabricate from a piece of scrap metal someday: a drill, a hacksaw, and lots of filing are in my future.
 
stepleton said:
Happy to do that. We can exchange details closer to my travel date.

One other thing I need for one of the 4051s is one of the tall metal "puzzle pieces" that link the space bar to the stabiliser hinge. This should be reasonably straightforward to fabricate from a piece of scrap metal someday: a drill, a hacksaw, and lots of filing are in my future.
Click to expand...
I wonder if those may be similar to MX space bar hinges. I certainly didn't see a diagram for that in either 4051 or 4052 parts manuals.

Does it look similar to this?
https://www.amazon.com/Original-Plate-Mounted-Stabilizers-Satellite-Mechanical/dp/B07K8F6692

Cherry Original Plate Mount Plate Stabilizers Satellite Axis 7u 6.25u 2u for MX Mechanical Keyboard Big Keycap​

 
No, unfortunately (or fortunately as it's easy to fabricate): it's just a flat metal piece with a tab that inserts into the space bar and a kind of puzzle-like round notch that receives the stabiliser "plate" (instead of a bent wire, it's more like a piece of FR4 circuit board material). You'll see it easily when you take apart your keyboard to replace the keyswitches.
 
stepleton said:
No, unfortunately (or fortunately as it's easy to fabricate): it's just a flat metal piece with a tab that inserts into the space bar and a kind of puzzle-like round notch that receives the stabiliser "plate" (instead of a bent wire, it's more like a piece of FR4 circuit board material). You'll see it easily when you take apart your keyboard to replace the keyswitches.
Click to expand...
You don't need to take the keyboard apart to replace a key switch, just remove the keyboard assembly.

I unsoldered the key switch from the PCB, then pried the key switch tabs from the top of the keyboard to remove the key switch.

I did a little damage to the hole using a screwdriver to push the tabs securing the key switch - but the new key switch snapped into place and I soldered the key switch to the PCB - and you are done :biggrin:
Next time I would use a plastic spudger instead of a screwdriver.

Here are photos of my May 2018 broken 4054 key switch repair.
I had not tried to clean the crud from the key caps at that time. I certainly didn't want to remove any key caps to clean them for fear I might break more switches.

removed 4054 keyswitch3.jpeg

unsoldered 4054 keyswitch.jpeg


I'm pretty sure the dark spots on the solder pads are based on lighting - I didn't see bad solder joints at the time.
 
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I found a box of DEC VT320 keyboard keycaps while I was tidying up at work a few months ago.

The box also contained a little tool for removing keycaps.

Guess where the box of keycaps and the tool are now... No prizes... They were part of the store that I was disposing of - so no theft was involved!

Dave
 
what does the keycap removal tool look like Dave?

For the keycaps that are broken off - I used a pick to pry the broken end out of the keycap before installing the keycap on a new switch.
 
nikola-wan said:
You don't need to take the keyboard apart to replace a key switch, just remove the keyboard assembly.
Click to expand...
Yes sorry, that's what I had in mind. Once you've lifted out the keyboard, gaze down the front of it edge-on as if you were eyeing the filling of an enormous sandwich. You'll see the workings of the spacebar stabiliser right in front of you. Hard to describe in writing, very clear once you see it...
 
I received my Alvin 12"x18" cutting mat today - it makes a fine Tektronix 4051 or 4052 keyboard protector. I trimmed a notch on the top corners to fit closer to the display and trimmed 2.5" off the bottom edge.
The Alvin 8"x12" cutting mat is perfect for protecting the display and tape drive opening.

I will have to measure the 4054A keyboard and display for the correct sizes as I know the keyboard section is wider due to the thumbwheel X and Y cursor controls to the right of the numeric pad.

4051-4052 keyboard protector.jpeg
 
Thats an interesting idea. The 12x18 is somewhat more from Amazon UK at 23.38GBP Funnily enough I was thinking about making one maybe out of wood or hardboard, but these go well with the Tek grey. I might have a look around the thrift or craft shops. They often sell similar boards.

Tom, I would be happy to get a couple more switches from you for spares if there are any left erm, to spare.
 
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