This one has been in the works for a while now. Thanks to robm for sending/loaning his driver & lamp boards (please don't look any further in this thread Rob
).
I have re-commenced the project at the request of a collector in the UK who is keen for a board. Also there is a company in the USA that is re-making the foil printed topper card so I suspect there will be a spike in interest for these boards. We intend to do the lamp board as well because LEDs just don't cut it in this application. Many changes will be made to the lamp board however.
The first thing to do is research common problem and faults and the main one with these boards is the 2 x bridge rectifiers. The originals are rated at 2 amps and often go open circuit. last China trip I obtained a box of 4 amp inline bridges with this project in mind. I also grabbed some TO-92 case, 1A darlington transistors as these are very expensive and difficult to find in Australia.
Here is the board sent by Rob:
Time to measure up the overall size - mounting hole locations and sizes. This is one area that causes the most problems when re-creating boards - these dimensions must be spot on or the entire batch of boards is wasted.
Then whack the parts in the correct places on the layout making room for any changes - in this case the slightly larger bridges and the more robust, board mounted heatsink for the 7805 regulator. The connectors all have to be the correct type and in the same place as the original board so that the replacement is a direct drop in part.
Here the board has been laid out with mounting holes and parts and the main power tracks have been put down:
Time to start with the smaller signal tracks. A lot of these are run under the ICs and between IC legs and can be difficult to follow. You can't always take the circuit diagram as being correct, the number of times I have found mistakes in schematics when laying out boards is amazing. To this end (where possible) it is easier and faster to cut the ICs off the sample board (sorry Rob, stop looking
). They can always be replaced later although it's often better to use the parts to simply make up a new board as there will be many improvements.
That's about where we are at but I do want to have this artwork finished in time to include with my next board order in a couple of weeks so we will continue on with it. More as we progress.
