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New Dimmer Switch "Squeals"?

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scardini1 Avatar
scardini1 Gold Member Jim Moscardini
Great Mills, MD, USA   USA
1968 Triumph GT6 "Rocinante"
2003 Jaguar XKR "Kitty"
Hi guys,

I'm interloping from the Spit/GT6 forum. I recently put in a dimmer switch I saw for a TR6, which I now see available for almost all Triumphs. It "squeals". It's loudest at full brightness and gets quieter (and sorta "beeps"winking smiley as I dim the panel lights, but it never shuts up completely. I think it will be loud enough to actually hear while driving!

Does anyone here use this dimmer? Has anyone else experienced this squealing sound?

Thanks! - Jim

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David DPS Avatar
David DPS David S
Louisville, Kentucky, USA   USA
Check this:
http://www.mikeholt.com/mojonewsarchive/All-HTML/HTML/High-Pitched-Sound-When-Lights-Turned-On~20000725.php

I had the same noise with overhead light fixtures. Annoying noise from dimmer. Switched to LED lights and resolved. Get a better dimmer or better light bulbs. Maybe turn the stereo up or get a louder exhaust system.



Edited 1 time(s). Last edit at 2017-01-05 11:11 AM by David DPS.

scardini1 Avatar
scardini1 Gold Member Jim Moscardini
Great Mills, MD, USA   USA
1968 Triumph GT6 "Rocinante"
2003 Jaguar XKR "Kitty"
Hi David - THANKS!

Yup. I've read about some of those experiences, but they're all AC related, which could explain where the oscillations originate. I can't understand where the oscillations necessary to create noise could come from in a DC system like our cars.

Was your overhead experience with a car or with a house? Do they make "dimmable" LED instrument bulbs? (that has not been my experience, but I haven't looked very hard)

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Brian Oklahoma Brian Plotkin
Edmond, 73012, USA   USA
1968 Triumph TR250 "Kevin"
The original dimmer switches were just variable resistors. I can't say if the new ones are as well.

Resistors of all types can make noise. The AC hum amplifiers make is primarily from resistors. However resistors shouldn't make loud high pitched noises. This is typical of a poorly made. The switch could be carrying more current than is spec'ed for the resistor. Typical of poor quality replacement parts.

The original dimmer switches are fire hazards - especially as they get older. If you are like most of us, and tend to run with the dashboard lights fully bright, I'd bypass the dimmer switch. Tie all of the wires together with a large wire nut. Then in order to avoid potential shorts wrap it all in electrical tape. You won't be able to dim your dashboard, but since maximum bright is still pretty dim the switch isn't very useful anyhow.

Put the old switch back in the hole in the dash and return the new switch to the vendor (get your money back). Tell them its faulty (making noise).

If you want brighter dashboard light, switch to LEDs. I can't speak on how well they work with a dimmer.

scardini1 Avatar
scardini1 Gold Member Jim Moscardini
Great Mills, MD, USA   USA
1968 Triumph GT6 "Rocinante"
2003 Jaguar XKR "Kitty"
I may try a swap, ... IF I can figure out which supplier I got it from.

David DPS Avatar
David DPS David S
Louisville, Kentucky, USA   USA
They do make dimmable LED lights, not making a recommendation. They are expensive and even LED bulbs are associated with humming.
Here is an example:
https://www.superbrightleds.com/vehicle/1976-triumph-tr6-instrument-panel-light-bulb?make=78&model=1648&scc_id=1416&year=1976

I expect a wider selection is pending.

It looks like all the usual vendors are selling the same Lucas dimmer. So swapping one for another may not work out. I see old TR6 dimmers on Ebay and wonder about using an old one.

scardini1 Avatar
scardini1 Gold Member Jim Moscardini
Great Mills, MD, USA   USA
1968 Triumph GT6 "Rocinante"
2003 Jaguar XKR "Kitty"
Thanks David.

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