DIY Refurbishment of Zero 1 Keypad

The Hornby Zero 1 is the simplest and cheapest DCC system to operate, albeit with limited functionality. Second hand controllers and chips are available from ebay. The biggest downside is the loco chip board that is too big to fit into some modern tank locomotives and it does require some ingenuity to fit into some larger modern locos.

The system was launched by Hornby in the 1980s and after 40 odd years it is no surprise that the keypad fails. It is the weakest part of the controller design. The failure is due to the carbon tips of the elastomer keypad keys wearing away. Happily it is easily fixed without the need for electronics knowledge or great expense.

Sorry, no pictures.

1. Remove from power source
   
2. Drill out the 10 rivets holding the unit top to base
3. Lift off the top starting at the rear, rotating to the front taking care not to damage wires between base and top
4. Remove the small phillips screws that hold the keyboard in place
5. Gently easy back the two keypad front retaining clips to release the keyboard and fold away to reveal the elastomer keypad
6. If the button circuit areas on the printed circuit board look dirty then clean with Isopropyl Alcohol and if still dirty use a fibreglass rubber or scalpel taking care not to destroy the circuit tracks
   
7. Brush away any detritus on the black pads of the elastomer keypad with a dry paintbush.
   
8. Take some aluminium kitchen foil and a paper hole punch that has a 5mm punch and punch out 17 circles. If the punch is larger than 5mm then cut squares instead that are a little larger than the black pads of the elastomer keypad
9. Test fit an aluminuim pad over a black pad to ensure it is wholly contained within the well and below the top surface
10. Glue the aluminium pad on top of the carbon pad with a small drop of super glue and check it has set, i.e. does not slide off the pad
11. Press lightly on the fixed aluminium so that it slightly wraps down the side of the carbon pad
12. Repeat for all buttons
13. Refit the keyboard and top to base. The top should be located at the front first and then rotated over the rear
14. Since the unit was held together with rivets it is not be possible to fix the top to base easily. You might try a couple of small wood screws screwed into the palstic holes.