Back-lit switches: Difference between revisions
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Tek introduced '''back-lit pushbutton switches''' at the end of the 1960s in the 7000 scope family. | Tek introduced '''back-lit pushbutton switches''' at the end of the 1960s in the 7000 scope family. | ||
There is one miniature 5 V incandescent lamp per interlocking group of buttons, with clear plastic light guides reflecting the light to the backs of the transparent plastic buttons. In the Off state, a small metal flap covers the un-lit button end, in the On state it is pushed open. | There is one [[150-0048-01|miniature 5 V incandescent lamp]] per interlocking group of buttons, with clear plastic light guides reflecting the light to the backs of the transparent plastic buttons. In the Off state, a small metal flap covers the un-lit button end, in the On state it is pushed open. | ||
The lamps are not supplied from the standard +5 V (logic supply) rail but from a separate lamp supply rail which is not present in all mainframes (e.g. missing from | The lamps are not supplied from the standard +5 V (logic supply) rail but from a separate lamp supply rail which is not present in all mainframes (e.g. missing from 7xx3 series scopes - see [[Media:040-0686-01.pdf | modification 040-0686-01 adding this supply]]). In mainframes that do supply the lamps, the lamp voltage (and therefore lamp intensity) can often be varied, e.g. through a 3-way (off/mid/high) switch in the back of the instrument. In the [[7904]] (non-A), this is a front panel control. | ||
<gallery> | |||
backlit-sw-1.jpg | |||
Tek-pushbutton-light-on.jpg | |||
Tek-pushbutton-light-off.jpg | |||
</gallery> | |||
[[Category:Repair issues]] | |||
[[Category:Electromechanical components]] |
Revision as of 22:12, 15 June 2020
Tek introduced back-lit pushbutton switches at the end of the 1960s in the 7000 scope family.
There is one miniature 5 V incandescent lamp per interlocking group of buttons, with clear plastic light guides reflecting the light to the backs of the transparent plastic buttons. In the Off state, a small metal flap covers the un-lit button end, in the On state it is pushed open.
The lamps are not supplied from the standard +5 V (logic supply) rail but from a separate lamp supply rail which is not present in all mainframes (e.g. missing from 7xx3 series scopes - see modification 040-0686-01 adding this supply). In mainframes that do supply the lamps, the lamp voltage (and therefore lamp intensity) can often be varied, e.g. through a 3-way (off/mid/high) switch in the back of the instrument. In the 7904 (non-A), this is a front panel control.