Keyboard
Wang 600 Keyboard
The keyboard was dirty and its foam overlay was crumbling. Strip down and cleaning of these keyboards is time-consuming but rewarding.
Closer examination showed that the keytops were different to other Wang machines, being rather ’nicer’ with rounded edges. The key-feel was different and the stripdown revealed keyboard-style key mechanisms rather than the industrial microswitches that Wang had used since the early 1960s. Cleaning was straightforward and all parts appeared to be in good condition.
Incandescent Indicators
Wang 600 Keyboard
Wang 600 Keyboard
Wang 600 Keyboard
There are three incandescent indicators which are now nearly fifty years old. Replacement requires a fair bit of disassembly and with this in mind the incandescents were replaced with LEDs while the keyboard was otherwise dismantled.
Replacement can be done without altering appearance.
9946 DTL IC Testing
The keyboard has a number of flip-flops formed by cross-connected NAND gates, these provide debouncing for
- four ‘ROM restart’ keys (Prime, Set PC, Record, Verify),
- Step key and
- Shift key.
Past experience with another Wang 600 had shown that the Fairchild 9946 DTL quad NAND ICs were prone to failure. Since failure of any of the above keys would cause severe problems, the keyboard was powered up separately and the six flip-flops were tested. All functioned correctly, eliminating one possible cause of a non-functional machine.
Wang 600 Keyboard
Wang 600 Keyboard
Reassembly after cleaning gave a nice-looking keyboard with high confidence that it would work correctly.