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Level42

XL keyboard -> FFC adapter PCB

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Just a little post to show my most recent little PCB.

 

Because I work quite a lot on the internals of my beloved 600XL the keyboard flex connector has grown more and more as extremely irritating to me.

Surprisingly, mine is still working find but if you have a look at it you wonder how....

 

The flex wears because of lots of disconnects and reconnections.

Another irritating factor is that the length of the flex between the keyboard and the mother board is very short. If you just want to open the case quickly and put the keyboard next to the machine for a moment, it's almost impossible. I have often put some kind of support next to it to keep the keyboard upright ...which often failed and made the keyboard crash somewhere.....

 

Anyway...I figured there might be a solution for it by replacing it by something more modern.

 

I learned about the much smaller FFC connectors and (flat) cables through working on Apple hardware and figured this might be a good idea to use.

 

I searched for ready-made adapter PCB's. These exist but they all go from FCC to 2x pin-header connections.

 

So...I fired up Eagle-CAD and designed my own :)

 

I did the routing fully manually because the auto-router messed up badly. This way I had only a few via's and a neat looking design.

 

While I was at it....I figured it would be a great opportunity to implement another little idea I've had for some years: wire an extra button from a game-controller in parallel to the space-bar input. This would be awesome for games like Dropzone and some others that use the space bar as a "bomb" or "kill all on screen" function. The very recent Scramble conversion is also a great game for this.

 

Since I had all the traces of the keyboard matrix inputs on my little PCB anyway, it was simple enough to route the two "wires" that when shorted generate the space-bar code to a 2 pin header connector.

I actually also thought about the 1200XL F1,F2,F3 and F4 keys but I finally decided against it since I know of absolutely no application for them _and_ it would get really tight on such a small PCB surface....

 

I recently received the parts and the PCB from China. I am not a fan of SMD soldering and the plastic of the connectors on my first 2 PCBs did melt a bit but...the connectors actually still work fine.

 

So how does it work ? I use two of my PCB's ast hey can be "mirrored" without a problem. To be honest, I did create a ground-plane which is connected to the GND pin of the keyboard connector.....now.....looking back at this, this was very unnecessary because there is no very high-frequency stuff going on and it's a tiny PCB. SO......since I use the same PCB "in mirror" at the keyboard side, there is now one of the "random" connections have a large amount of copper....but it doesn't harm how it works in any way :)

Also, naturally, you can only use the space-bar break-out connection on the little PCB which is soldered to the motherboard.

 

Now pics say more than words (already way too many here now) so, have a look:

 

 

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To use the PCBs, naturally, I had to desolder the PCB/edge connector from the XL's motherboard and solder it to the tiny PCB which is going to be connected to the flex.

 

The other PCB I equipped with regular header pins on the under side and soldered those to the XL PCB.

 

As you can see on the keyboard side, I wrapped the flex around for now. This is not my end-goal, I will be cutting back the flex to as close to the keyboard as I can so it will be a much nicer sight and set-up.

 

However, this was for testing it now.

 

And it works just great.

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This is a very good idea for someone who is regularly going into their machine. Neat that you can use the same PCB on both sides.

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this would have saved so many 130XE keyboards it's ridiculous!

I need to check the pin out to see if it will work n 130XE. I shouldn’t have made the ground plane.....then it would be simply 24 pins 1 on 1 on both sides and would definitly work. Space bar breakout probably would need to be connected to other pins I guess though....

 

If anyone is interested in my left over bare boards let me know. I received twelve boards , still 10 left. I will keep a an extra set though so there are enough for 4 computers.

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Fixed the keyboard side of things.

 

I puzzled around but decided to go for this method using hot glue. I cut back the Mylar quite a bit.

 

The PCB is angled compared to the metal plate. The connector is parallel to the diagonal fold in the metal. That seemed like a good point to glue it. The benefit of this was alto that the soldering sunder the PCB were not going to short to the metal. I used hot glue liberally to ensure further insulation. I pre-heated the metal of the keyboard so that the hot glue didnt set instantly.

 

With hindsight, I could have designed the PCB to use some of the small screw holes, although this would have made the PCB quite a bit larger. Also, the old large connector for the Mylar would have been better to install angled....but hey...this works fine too :).

 

If anyone is interested to apply this to their XLs.... I still have plenty of the PCBs and FFC connectors and cables available.

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I just sold my last spare PCBs (and flex cables and connectors).

 

if anyone is still interested in one or more sets, please let me know, I’m can order a new batch of PCBs if there is enough interest.

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Great idea! Thanks for the bump of your thread!

It just seems that i'm two years too late. ;)


So, I'd be interested in two sets if you happen to order a new batch.

 

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OK that's 6 sets so far here, and I got interest on Facebook for 6 sets too. (let me know if you posted your interest there too).

 

Anyway, enough reason to order new PCBs, connectors and flex cables.

 

Let me get the materials first and we'll go from there. Prices won't break the bank...not doing this for money but helping out fellow Atari users.

 

I'll post as soon as I have the parts here. Thanks for all the positive replies !

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Excellent, thanks !

 

Small update: I just updated the design a bit. Removed the unnecessary ground-plane and added a second break-in set of pins so not it is possible to use the break in for Space Bar generation on both XL and XE machines. So the PCB is now truly universal for XL and XE's.

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On 5/24/2020 at 3:28 PM, Level42 said:

I just sold my last spare PCBs (and flex cables and connectors).

 

if anyone is still interested in one or more sets, please let me know, I’m can order a new batch of PCBs if there is enough interest.

I am interested in at least two. 

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How hard are those connectors to solder? If not too hard, I'd be interested in a couple, too. Would be nice if a future new keyboard used this ;)

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On 5/26/2020 at 6:26 PM, ivop said:

How hard are those connectors to solder? If not too hard, I'd be interested in a couple, too. Would be nice if a future new keyboard used this ;)

It's not a regular solder job for sure. It is a SMD sized connector. There are several techniques to do it:

1) Hot air soldering. This requires a dedicated hot-air soldering station. They are quite cheap to get from Asia these days. This is how I did it. The positive thing about this method is that it's cheap. The negative is that you are running the risk of overheating the plastic part of the connector and it melts. This happened to my first PCB set a bit, but it still works fine.

2) (Dedicated) SMD soldering oven. These are quite a bit more expensive if you get a dedicated one. There are also many hacks of regular electrical ovens to be find on-line. The trick with oven soldering is that it reaches a certain temperature, keeps it just long enough and then slowly decreases the temperature again. In other words, this is rather hard to do with a regular oven, but it can be done.

3) a traditional soldering station with a very fine tip and using a method called "drag soldering".

All these methods require the PCBs to be cleaned with some pure alchohol before soldering, then applying flux and then applying (about) the correct amount of (fresh) solder paste. 


For all soldering methods: you can find loads of information and videos about all of them on the internet. It goes to far to explain them all in detail here.

I have asked for a price to have the connectors soldered at the PCB factory and I will report back about that ASAP but it's clear that ordering bare PCBs is a lot cheaper. On the other hand I could do the soldering, but I have to say I'm no SMD soldering expert and it's definitely  not my favorite pass-time :) I guess I would become better by doing more though.... LOL.

OK, more info ASAP.

 

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Many thanks for these, I installed them into my 600XL and its so much easier to access now without worrying about destroying the keyboard. I just ordered a long ffc cable too to give even more flexibility!

 

 

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I would take two sets, please, preferably with the SMD part soldered. 

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Great solution👍!

 

I´m in with 5 sets please (with SMD parts soldered of course please, cauz´my eyes are getting week last years 🤓...)

 

Gtx.,

andY

Edited by andymanone

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I am interested in two to four sets, definitely four if they are soldered. 

 

Kind regards, 

Klas

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I should get a hot air station. Maybe I can also do my VS1053 waveblaster board. Drag soldering sucks I suck at drag soldering ;) I have an oven for non-food purposes, even calibrated it so I know how hot it really is, but never used it yet for SMD stuff. Would be nice to have an SMD stencil, although perhaps not really needed for only one SMD part?

 

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How much per set? I have an 800XL I need to repair the keyboard cable on and this looks to be one of the best fixes I've seen yet.

 

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I'll have to establish a price once I have everything here. 

 

I will offer sets of parts only (so you have to solder the connectors yourself) and sets with the connectors soldered by myself.


I decided not to go with having them soldered at the PCB factory because it raises cost significantly. It does mean I will need to do the soldering of the complete sets myself so naturally these will be a bit more expensive than the "parts only" sets.

 

Currently the flex cables have arrived, connectors and PCB's are still on their way. I'll post as soon as they are in.

 

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