restoration project: Model 1 Keyboard

[Patrick.B (TTR)]

after I spoke a few days ago with Johanes having being blessed with his visit at my place in Houston, and him repeating 3-4 times "why do you hate restoring Model 1, they are so easy!"
I decided to open the box of Model 1 parts I was given by various sources and see if I could attempt to repair, I always have considered the model 1 not just ingenious feat of commercial decision, but a poorly design and weak hardware construction, but of course it was "inexpensive" so this could go for other such era systems trying to get purchased at the time.
I apologize in advance, I am sorry for the purist this offends, it is only my perception of the model 1 and why until today I always stacked and sold them for parts.

I always saw the model 1 being the step child of so many blogs, web sites and long discussion on how to troubleshoot and repair them, how to constantly having to "tweak them like an old Harley" to get them down the road.
I hope my inexperience and jaded perception of the model 1 not deter you to read more of my trials and tribulations to attempt my very first TRS-80 model 1 Keyboard repair.
I open the "junk box of Model 1's, yes I have a number of them, cases, keyboards, expansion units, monitors etc... and the incredible number of cables required to run them.

I pulled three parts from it to test my hand.. a keyboard and main board and a small device someone explained was a level II upgrade board.
As many parts given to me, all 3 are apart from each other, the flat cable holding the keyboard and main board together was cut a long time ago in two as was the upgrade board had its four leads cut from the main board.. sighs...
So the basic repairs begin.

https://imgur.com/C46hFce

https://imgur.com/V3cLdzu

https://imgur.com/XYC52jj

so the first part was easy enough, the soft pads holding the Rom kit board where split so a quick clean and double sided tape between the pads and boards and voila... back to where it belong, followed with a r4emovale of end of wires on main board and resolder the 4 wires to the main board back in their place.. so far simple soldering techni8cs used. so far so good.

https://imgur.com/iubA9CA

next I attacked the flat cable , not having a spare and particularly hating the finality of a soldered wire in place with no means to part both boards apart from each other to repair or change something on it, was always a quirk of lazy and inexpensive hardware I was talking about easier. so I unsoldered both end of the cut flay cable, and replaced both board ends with pin thru soldered mount headers pins. the one on the main board pointing downwards into the case and the ones on the keyboard pcb pointing upwards

https://imgur.com/BZvEZMf

https://i.imgur.com/XM6VQJx.png https://i.imgur.com/RWbM13r.jpeg

 

[Patrick.B (TTR)]

I used a 40 pin cable, I had one with a already installed femalke idc connector on one end, so after cutting it about 5 inche long I slipped a new c connector on other end without crimping it in place, this is to be seen in next step

https://imgur.com/B9901zw

I attached the premade connector of one end of the cable to the main board then assemble the keyboard atop it into the bottom portion of the case then plugged the loose connector in place and adjusted the length of cable needed to join both loosely as possible due to "space limitation this is only a few inches long, marked the cable then crimped the connector at the indicated line and trim the excess off.

https://imgur.com/rsPBPnR

https://imgur.com/Y5WssvT

the fitting is simple the bottom connector must NOT use a security loop , its just makes it too long inside the case and nothing fits properly. but just the main connector in place and the looped on on the keyboard portion is fine. and does give teh cable proper directional motion and is a clean fit inside the case as seen here.

https://imgur.com/bjX6Mfq

 

[Patrick.B (TTR)]

then assemble the parts together... and voila step one... done... tomorow... well see if it powers up, and shows something on the monitor aside the expected scrambled graphics.

https://imgur.com/Ix6OPI3

https://imgur.com/Lvirpcf

https://imgur.com/GCtvKwY

 

[cjs]

I always have considered the model 1 not just ingenious feat of commercial decision, but a poorly design and weak hardware construction, but of course it was "inexpensive" so this could go for other such era systems trying to get purchased at the time.

Well, there was a reason we used to call it the "Trash-80." :-)

But when considering design, you need to remember that cost is one of the key factors in design. If you make a great computer, but nobody can afford to buy it, is it really a great computer? Or is the better computer the one that people can actually afford? The TRS-80 was half the price of the Apple II, and that was one of the reasons it sold vastly more units in its lifetime. (Another reason was simply that it had much better distribution.)

And, while the hardware implementation was somewhat dodgy (clearly their engineers didn't have as much experience as Woz and the CBM folks), they did a number of things pretty well. Enough that, if I were transported back to 1978, I'd probably choose it over the PET and Apple II. (Though part of the reason for this is that I'm not much of a games or graphics guy.)