Touch Switches on Lamps

May 22, 2020 Last reply: 6 years ago 9 Replies

Metal bodied desk lamp, bedside lamp type things - I have a pair I liked which were on, off, dimmable just by touching the metal base with no other switch. There is a black thing on the cable which actually is the touch switch device. Both have conked out one after the other.



Qu 1 Are these switches inherently unreliable / short lived? Qu 2 Replace the switch with another the same? a dimmer? a mechanical switch? or what?



Tim W


What sort of bulb do they dim? Tungsten? I've had problems if a bulb has blown by shorting out its filament: the momentary extra current can fry the triac that dims the bulb.

They are G9 - little 240v capsules with filaments. Now you mention it it may be that the bulb goes, then I replace the bulb and it still doesn't work. TW

It very much depends how they work. There has to be an extra wire in the lead between the gubbins and the lamp, assuming the blob you mention is in fact the switch. I suspect its not, its an anti interference suppressor so mains borne stuff does not trigger the lamp. Normally the switch is at a very high impedance so it can pick up either capacitance from you or more likely the 50hz hum from your finger. Can you get inside to see? If they have failed off it could be almost anything from the little chip they use, or the triac they control the load with, but its been my experience they go permanently on if that is the issue. Brian

It is the switch, an inline black plastic cased fitting, on the back it is marked as such.

TW

Probably works on this principle.

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Most probably not.

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The ICs behind this are subject to a great deal of ESD, so perhaps not surprising they have a limited life-span.

I had one which took an SES halogen lamp and had three dimmer settings. It stopped working so I took it apart, removed the dimmer/touch device (plastic lump inside the base), wired it through and fitted an inline switch.

I bought another one - same make and appearance - which didn't dim and took an LED SES lamp. That's still working and may work for longer as it switches a smaller current.

The first one I could replace the lamp with an LED except I have several spare halogen lamps.

little capsule jobs are at the highest risk of momentary short or arc-over on failure. If that happens you need a new triac at least.

NT

snipped-for-privacy@gmail.com formulated on Saturday :

+1

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