36,230
edits
Back-lit switches: Difference between revisions
no edit summary
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[File:Tek-pushbutton-light-on.jpg|400px|thumb|right| Switch ON state]] | [[File:Tek-pushbutton-light-on.jpg|400px|thumb|right| Switch ON state]] | ||
[[File:Tek-pushbutton-light-off.jpg|400px|thumb|right| Switch OFF state]] | [[File:Tek-pushbutton-light-off.jpg|400px|thumb|right| Switch OFF state]] | ||
[[File:Tek 7k DPDT PCB switch 1.jpg|400px|thumb|right| Switch interior]] | |||
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. | ||
==Lamps== | |||
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. The lamp is powered all the time. In the Off state of the switch, a small metal flap covers the un-lit button end, whereas in the On state, this flap 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. The lamp is powered all the time. In the Off state of the switch, a small metal flap covers the un-lit button end, whereas in the On state, this flap is pushed open. | ||
| Line 8: | Line 10: | ||
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 some early 7000-series scopes like the [[7503]], [[7504]], or [[7904]] (non-A), this is a front panel control. | 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 some early 7000-series scopes like the [[7503]], [[7504]], or [[7904]] (non-A), this is a front panel control. | ||
==Contacts== | |||
The switch consists of a mechanical interlock with sliding plungers that is attached on top of a PCB. This plastic part is screwed to the front panel (under the printed aluminum cover plate). | |||
The contact surfaces are gold-plated PCB traces, the switch contacts are small metal see-saw style springs point-welded to a center support pin that is soldered into the PCB. | |||
The contacts can break off from the support, giving no or intermittent conduction. | |||
| Line 14: | Line 24: | ||
Tek-pushbutton-light-on.jpg | Tek-pushbutton-light-on.jpg | ||
Tek-pushbutton-light-off.jpg | Tek-pushbutton-light-off.jpg | ||
Tek 7k DPDT PCB switch 1.jpg | Dual DPDT switch interior (mV / mρ mode switch from a [[7S12]]) | |||
Tek 7k DPDT PCB switch 2.jpg | |||
</gallery> | </gallery> | ||
[[Category:Repair issues]] | [[Category:Repair issues]] | ||
[[Category:Electromechanical components]] | [[Category:Electromechanical components]] | ||