Sony HB-F900 keyboard repair?

By lintweaker

Master (226)

lintweaker's picture

04-04-2020, 13:19

A couple of weeks ago I got my hands on a Japanese Sony HB-F900 (the black one). It is in decent condition but needs a good clean.
One of the, bigger, issues is the keyboard (KBD-13 (B) ). Most keys do not work.
I opened up the keyboard and luckily it is not a membrane one, but one where the key domes complete the circuit on the PCB to do a key press.

Any tips on how to restore the keyboard to working condition? What is a safe way to restore conductivity of the key traces?

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By rderooy

Paladin (683)

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04-04-2020, 16:47

If it is the traces on the membrane, you may want to try conductive ink.

By Meits

Scribe (5804)

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04-04-2020, 17:22

I remember keys being hit too often/too hard (cursor/space) wore out the pcb. But that's patchable. But if most keys do not work, is the cable ok?

By Manuel

Ascended (16365)

Manuel's picture

04-04-2020, 18:06

I'd first completely clean the keyboard, especially the conductive black tips. And you could use a soft pencil to make them conductive again. There's LOADS of screws though... done it too often in the past. My reference is the KBD-12P.

By Alexey

Guardian (2704)

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05-04-2020, 01:57

I usually take a pencil with more or less soft center and use it on the black pads for better conductivity.

By lintweaker

Master (226)

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05-04-2020, 08:40

Thanks! So far I did some cleaning (really needed) and have used an rubber eraser on the traces for the keys. It works a bitter better. Should those traces be shiny copper? The erase took of a bit of black but there not shiny.

By Manuel

Ascended (16365)

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05-04-2020, 10:09

Did you clean the black rubber tips?

By lintweaker

Master (226)

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05-04-2020, 10:23

Manuel wrote:

Did you clean the black rubber tips?

Not yet, next on the list

By jltursan

Prophet (2273)

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05-04-2020, 11:37

Quote:

Should those traces be shiny copper?

The shinier, the better. Thoroughly clean it with isopropyl alcohol until all residues are gone.
The rubber tips are the weakest part and usually are hard to restore 100%, you can use a q-tip with alcohol to remove the possible accumulated dirt in the surface and then, restore its conductivity using the above mentioned pencil or silver paint (expensive but lasts longer than the pencil). All in all, a good amount of work.