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Old 18th Dec 2018, 1:25 pm   #1
ekcopyephilips
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Default Replacing dial lamps with LEDs

Hi All

Ive seen before that some people have changed the filament dial bulbs on a Bush DAC90A to LEDs.

How easy is this to do, and how would i work out the value of resistor to use to limit the current and keep the current to the rest of the valve chain correct.

Cheers

Mike
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Old 18th Dec 2018, 2:58 pm   #2
Al (astral highway)
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Default Re: Replacing dial lamps with LEDs

Hello, it is possible but have you considered the colour temperature? When I’ve done this (with another radio ) I was disappointed with the intensely white colour temperature.

Many people including me have good stocks of old dial light bulbs so ideally , ask for a replacement first
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Old 18th Dec 2018, 3:08 pm   #3
paulsherwin
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Default Re: Replacing dial lamps with LEDs

You certainly shouldn't use anything colder than warm white or it will look completely wrong - this applies to any incandescent replacement, not just in a DAC90A. Yellow LEDs often look best but you need to experiment. A lot depends on the tuning scale design.
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Old 18th Dec 2018, 4:37 pm   #4
kalee20
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Default Re: Replacing dial lamps with LEDs

I have had several LEDs from Bright Components (they have an eBay presence) - no connection other than a satisfied customer! - the warm white types are really good and I have used them as dial lights in, would you believe, a Vidor CN420a battery valve radio.

If I was LEDising a DAC90a (which I'm not), I'd be inclined to connect them in series with the HT rail, maybe in series with the 10kΩ smoothing resistor. It would have the slight disadvantage that you'd get no light at all till the radio warmed up, but it is probably simpler than fitting a diode bridge and mucking about with shunt resistors around the current bit of circuitry where the incandescent lamps are. You could use 3 or 4 in series, mounted on a little sub-panel of matrix board, and spread the illumination more evenly.
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Old 18th Dec 2018, 5:12 pm   #5
ekcopyephilips
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Default Re: Replacing dial lamps with LEDs

Hi Guys

Thanks for the reply's, probably far easier to just get some filament lamps, im all for an easy life.

Cheers

Mike
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Old 19th Dec 2018, 9:35 am   #6
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Default Re: Replacing dial lamps with LEDs

Agreed! J.
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Old 23rd Dec 2018, 12:38 am   #7
murphy512
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Default Re: Replacing dial lamps with LEDs

Have a look at this thread



https://www.vintage-radio.net/forum/...d.php?t=141740
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Old 23rd Dec 2018, 1:56 pm   #8
Mike. Watterson
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Default Re: Replacing dial lamps with LEDs

It's easy to get the right current rating of lamp. An LED is a modernisation, like FET instead of RF Pentode.
The current rating is more important than voltage.
Apart from the fact it's a modernisation and not restoration of a typically 60 years+ old radio the appearance is just wrong. Both at power on and running.
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