Sony HB-F1 MSX2 restoration (Keyboard issues)

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By NoGoodCitizen

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11-02-2022, 18:55

Hi everyone! I'm new here (haven't used a forum much in the last several years)

I acquired a junk HB-F1 through Yahoo! Auctions Japan, this is my dream MSX2. That's right, I'm another Metal Gear fan who fell in love with it through Metal Gear Solid V.

When it arrived it would not stay powered on, it crashed often. I thought this to be a RAM issue, but as my MegaFlashRom had not arrived yet, I figured I would go ahead and do basic maintenance anyway.

I reflowed the entire motherboard - yes, every single point - giving a lot of suspicious looking contacts new life with fresh solder. The freeze/overheat issue ended up being two components on the underside that were touching eachother in the "SOFTWARE" section. There was another similar issue in the "VIDEO" section, but I don't think that was causing any noticeable problems. Regardless, I fixed everything, the machine runs great now.

My only remaining issue now is the keyboard. When the MSX2 was received, the "O" key did not function. Thinking I would be dealing with a simple clean and refurbish, I took the keyboard apart. Big mistake.

The more I tinkered with it, the worse things got. At one point the green light would no longer illuminate, but I still retained function with most of the keys. Not being satisfied with this I continued to tinker, test and experiment more, everything from tightening/loosening screws on the keyboard's backplate to trying to scribble some graphite on the tracks that connect to the motherboard connector.

Now I am faced with a keyboard that does not power on at all. I have jumped pins 2 and 7 on the motherboard connector and can confirm there is still input, but the keyboard itself does not want to acknowledge being connected to the system any longer.

Am I toast? I noticed the HB-F1 is not in the membrane group buy. I would really like to fix this, as the membrane is in mostly good shape with a couple slightly weathered spots on the tracks of the membrane. The ribbon cable has been creased to a slight degree (which I've tried my best to massage out) by the previous owner.

Overall this is a very nice system and I would hate to call it quits, I'm sure that I can salvage this membrane but might just be lacking the know how.

Any advice? Please let me know, and cheers for all the resources that are already on here. Smile


By Manuel

Ascended (19691)

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11-02-2022, 21:42

Did you see this?

It's probably not very helpful, sorry... I hope someone can help.

By NoGoodCitizen

Supporter (10)

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11-02-2022, 21:43

Unfortunately I think it's a little too late for that - as I said, the keyboard is acting as if it is not plugged in at all now (no key input whatsoever, no on light) Sad

By meits

Scribe (6577)

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11-02-2022, 23:43

I've done some membrane repair for another sony, panasonic and a philips computer. This can really be a pain in the butt...
What you really need is a multi meter with a continuity mode that beeps and a conducting ink pen. Follow each track on both membrane sheets and probe from point to point. As long as the meter beeps you're good. As soon as it stops you know there's a break in the line between both probes. Narrow it down and draw a line with the conductive ink pen to bridge that crack. You could do a blob on the crack or draw a parallel line from the points where both probes were when you found the crack.
Meassure from the tip of the connector to the end of the line and don't take too big steps while measuring since the lines have resistance.
Clean the connector on the mainboard as well. find some thin piece of plastic, fold a piece of normal paper around it (cut it to size), make it flow in alcohol and push it in and out the connector. Only up and down and don't use toilet paper or kitchen paper. Just smooth paper from your printer tray soaked in IPA. This way you prevent the chance your paper breaks and gets stuck in the connector.
Also check the graphite contact underneath the buttons. They can be revived with some pencil dust.

By NoGoodCitizen

Supporter (10)

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12-02-2022, 04:03

Meits, do you have a recommendation on what brand of conducting ink pen to use? I'm pretty terrified to use something wrong and have it chew up the membrane.

all suggestions appreciated (and thanks for your help guys) Tongue

By gdx

Enlighted (6445)

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12-02-2022, 09:08

After applying the conductive ink, wait until it is completely dry before rechecking the conductivity because the current does not flow until then.

By Grauw

Ascended (10821)

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12-02-2022, 16:10

I described my repair of a keyboard membrane track issue with conductive ink here. I used this conductive ink pen, but I’ve seen that there are also other types of conductive ink or paint that come in a jar which you can apply with a tootpick.

By NoGoodCitizen

Supporter (10)

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14-02-2022, 22:50

Thanks Grauw, for the sake of erring on the side of caution, I went ahead and purchased the ink pen you used.

It might be a little bit of a wait but it's worth it just to be correct.

By NoGoodCitizen

Supporter (10)

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15-02-2022, 00:51

Just as a quick follow up - does anyone have a link to a replacement header for the keyboard slot on the HB-F1 motherboard?

By NoGoodCitizen

Supporter (10)

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22-02-2022, 08:28

A little update! I managed to cobble together a solution that allowed me to reconnect the keyboard properly. 90% of the keys are working now, with the exception of:

Q, Y, I, P, [

A, /, -

6, |

Left Arrow

From what I can tell the majority of non functioning keys are on one bit, bit 6. My understanding of keyboard matrices is fairly limited but honestly if I could just get the left arrow key working I'd feel a lot better, as that would allow me to play most games.

There are a few weathered tracks remaining on the membrane but I did chop the ribbon connector down to remove all the damage there. Should I just wait for the pen now to attempt to repair the questionable tracks on the membrane? It looks to me like they aren't connected to any of the keys I am having issues with, but I could be wrong.

Just curious if anyone else has any insight on where to go from here.

By S0urceror

Master (220)

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22-02-2022, 08:43

I had similar problems with my keyboard on the Sony recently. I started repairing the membrane and ended up designing a replacement PCB.

Small issues can be repaired with conductive ink. Just use a multimeter to do a conductivity or resistance test. Follow the tracks till you got to the faulty part. Every key has only two possible routes to the connector because it’s a simple matrix. With a magnifying glass or your zoomed in phone camera you should be able to spot the issue and repair.

I my case the membrane was very bad. I had to repair multiple lines and things kept becoming worse. Hope it’s fine on your end.

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