Does anyone have experience fixing a keyboard membrane for a Sony HB-F1XV or the like?

Supporter (6)

14-11-2018, 14:03

Hi everyone I've been collecting and repairing retro consoles for some time now and I finally got my hands on a Sony HB-F1XV MSX2+. It was in working but poor condition when I got it, so I opened it up and did some minor repairs such as replacing some faulty caps and cleaning all the contacts. Now it fires up and plays anything I throw at without an issue, but I'm having a problem with the keyboard. The number keys (on the top row, not the ten key pad) 1 to 7 and 0 don't register when I type them. I opened up the keyboard and took out the membrane and it appears that the first trace to the left side of the ribbon cable is damaged and that's what's causing the keys not to register. As I test, I put a piece of desoldering braid between the plus pad of the 0 key and the end of the ribbon cable and I was able to get continuity between the two points, but obviously, this isn't a permanent solution. A friend recommended that I try using conductive paint or a conductive marker to connect the pad to the end of the ribbon cable. I'm not sure if this will work or not though, and given that good quality conductive paint/markers aren't cheap, I'd like to know if anyone has experience fixing one of these membranes and what they would suggest.
I've attached a photo to make it easier to understand what I mean. I drew a red line between the two points that I need to connect together.
Any advice would be greatly appreciated!

https://www.dropbox.com/s/wk87te0rmolmyh7/insane_in_the_memb...

By earl_of_thawndoure

Supporter (6)

15-11-2018, 04:08

Crap. I just found this information in another thread here:

Quote:

Let me start with advice: the "CircuitWriter" pen will eat through your MSX keyboard membrane, so that shouldn't be your first choice for fixing broken traces. Thus, I'm much worse-off than when I started, since lots more keys are dead now.

https://www.msx.org/forum/msx-talk/hardware/external-keyboar...

I guess I shouldn't try using conductive paint or a conductive marker then. Any other ideas? Copper tape seems like it could work, but I doubt the adhesive would stay put for any substantial amount of time.
Perhaps I could go with the conductive paint/marker and put a layer of electrical tape underneath it so that it doesn't eat through the membrane?

By hamlet

Scribe (4106)

15-11-2018, 06:39

Sooner or later you will buy a replacement membrane. I don't think there is a proper way to repair a membrane layer.

By earl_of_thawndoure

Supporter (6)

15-11-2018, 11:10

Thanks for the reply. I don't think the replacement membranes are for sale anymore though. All the links are dead.
How about using copper conductive tape with electrical tape on the top and bottom to eliminate any chances of shorting and cut out any potential noise? So, in other words, like in this pic. The blue represents electric tape and the red copper conductive tape. In theory it should work... I think.
https://www.dropbox.com/s/jjclgt43q1lsy8b/insane_in_the_memb...

By meits

Scribe (6543)

15-11-2018, 16:02

You could try silver paint or cut small pieces of aluminium foil and stick them over the breaks with adhesive tape.
I did use the latter on a panasonic membrane and it did work. But because I didn't like the idea I replaced the membrane after finding loads of other people who needed one/some as well and let mr. Maluf produce them.

I bet he received new requests and if he didn't change the rules he needs if I remember correctly (kill me if I'm wrong, but not too painful please) 100 orders. More than a year after I decided I needed replacement I got the membranes (got plenty cuz of plenty machines). Some MSX parts require a LOT of patience

By fr3nd

Expert (112)

15-11-2018, 16:39

I'd also be interested in a membrane for the HB-F1XV. I sent him a private message a while ago but I guess he didn't see it because I got no answer...

By meits

Scribe (6543)

15-11-2018, 20:12

Try finding him on facebook and PM him. That did the job for me.

By Algorythms

Champion (288)

15-11-2018, 21:23

Believe it or not, I've fixed two membranes by soldering wires onto the membrane. I cannot recommend this if you are not skilled at soldering, as you may do more harm than good, but here's how I did it:

- If the lines are covered in plastic, carefully scratch away the plastic on an area big enough for a solder joint on both sides of the breakage.
- Prepare a wire with the correct length and pre-solder the tips of the wire.
- Now to solder on the membrane you need to be really quick enough not to melt the plastic, but slow enough to get the solder flowing. Maybe practice on some scrap membrane if you have something lying around to get the timing right.
- Put some superglue on the solder joints afterwards.

I did this on a Panasonic membrane and a Sony membrane, and both have been working for many years after that. It's maybe 15 years since I had to do this on my A1GT, and it's still working.

By earl_of_thawndoure

Supporter (6)

16-11-2018, 05:49

Thanks for the different suggestions, everyone. I'm a bit nervous taking a soldering iron to the membrane, so I think I'll only try that as a last resort. I've ordered some copper tape for now and I'm gonna give that a try. In theory, even if I can't get a connection between the membrane and the tape, I should be able to just make a whole new trace from the 8 keys that don't work to the ribbon cable since they only connect to each other and the ribbon cable itself.
If it works, I'll put pics up documenting the process to help anyone else with the same issue. Keep your fingers crossed

By Pac

Scribe (7007)

16-11-2018, 17:13

There is a product called Wire Glue perfect for these kind of problems. Copper type should be a good solution too in my opinion.

By earl_of_thawndoure

Supporter (6)

23-11-2018, 07:43

Well, everyone, good news! I was able to restore the keyboard to fully working condition with nothing more than some copper foil and electrical tape. All I had to do was make a bridge between the last contact point on the damaged trace and the end of the ribbon cable using copper foil tape and bingo! It worked like new! I also put a layer of electrical tape over the copper foil tape (apart from the actual points of contact) to prevent any possible shorting (although this step is probably not necessary).

On my first attempt, I tried putting a layer of electrical tape on the bottom of the copper tape as well just to be extra cautious, and while this worked, it made the connector too thick to fit snugly into the slot on the motherboard. I was able to force it in, but in doing so, I damaged 4 more traces on the connector and ended up having to fix these as well. So for anyone doing the same repair, just apply the copper tape directly to the membrane. Since there's already a thin layer of plastic covering the traces on the membrane, you really don't need the extra layer or electrical tape anyway. Just be extra careful that the copper tape doesn't touch any unintended contact points.

Since you only need to bridge the final point of each trace to the end of the ribbon cable, you could technically fix even more traces than I did using this method. Although the more points you bridge, the more crowded things get. It seems to be the edges of the ribbon cable that get damaged the easiest. On mine, the four traces on the leftmost side and the three on the rightmost side of the cable all needed repair. Luckily, the two rightmost traces lead nowhere, so I got away with repairing (only) five traces.

Not sure if this is a long term solution or not, but at least for the time being it works and since all I did was put tape on the membrane, it's easily reversible in case I need to restore the membrane to it's original state (not sure why I would want to though).

Here are some photos of the repair. Hopefully this can help anyone else stuck in the same situation.
https://www.dropbox.com/s/xly8vualo00mzk2/20181122_153341.jp...
https://www.dropbox.com/s/syefkpodwc5aqb4/20181122_153354.jp...
https://www.dropbox.com/s/2d3dxbvcoc9ydlg/20181122_154940.jp...

I used the following copper foil tape from Amazon Japan (I couldn't find the same tape on the US website):
https://www.amazon.co.jp/gp/product/B017DG8KQE/

It's just 5mm wide, which makes it very easy to work with. I had to trim it down a bit to fit the connectors on the end of the ribbon cable, but this wasn't too hard to do.