The keyboard of the AMSTRAD CPC6128

I-IAmstrad CPC 6128, launched in 1985, is equipped with a keys low, representing an evolution from the previous model (CPC 464). This keyboard incorporates a modern design, both mechanically and electrically.

Technical characteristics of the keyboard

The CPC 6128 keyboard uses a printed flexible membrane, unlike the plunger system of the first model (CPC 464).Each key is based on two springs: an integrated key and a second between this one and the support plate. This design improves user comfort while reducing congestion.

The support plate keys is made of rigid PVC, reinforced by a thin metal plate located below, ensuring rigidity and stability. The tablecloth connecting the keyboard to the motherboard is flexible and fragile, making manipulations delicate.

Operation

The principle of detection of keys follows a matrix scan performed by the Z80 processor. When the user presses a key, the circuits printed on the membrane come into contact, sending an electrical signal interpreted as a user action.

A system shared with the second model of CPC 464

It is important to note that this type of keyboard is not exclusive to CPC 6128. Indeed, the second keyboard model of CPC 464 adopts exactly the same system:

• Key with integrated spring
• Printed flexible membrane
• PVC support plate
• Flexible connection tablet

This change marks a significant change from the first keyboard of CPC 464, which used a divers system and a motherboard bakelite.

Repair and maintenance

Over time, this type of keyboard may present contact problems due to oxidation or wear. Complete disassembly is necessary to access internal elements, as the keys are clipped and cannot be removed without opening the set.

It is possible to clean contacts with a specific electronic product or even replace the membrane if it is damaged. Catering kits are available in my shop, specially designed to facilitate the repair of these keyboards vintage.