DAC90A LED Bulbs ? - UK Vintage Radio Repair and Restoration Discussion Forum

Scottart · 26th Aug 2014, 3:07 pm

I've purchased a couple of these to experiment with as alternatives to the standard 'dim' scale lamps in a Bush DAC90A :

http://spiratronics.com/6v-white-led-mes-bulb-100a.html

http://www.spiratronics.com/data/2530.pdf

Has any one tried these, and what ( if any ? ) circuit adjustments are required - I'll wire them in series, and assume the 75 ohm parallel resistor ( R16) will need changing. I 'read' these LEDs can be used on 6V AC as well as DC - operating current 20ma each at 6v.

Don't want to do any 'major surgery' to the radio, just wonder if this could be a useful 'minor' upgrade

Thanks, Stephen

ThePillenwerfer · 26th Aug 2014, 5:01 pm

I've made my own LED lamps by re-using old MES caps, see below. After taking the photo I discovered that they work much better if you file the top of the LEDs flat.

No modifications to the set required beyond checking the connections to the lamp-holders. If they do need changing it won't affect the operation of standard lamps if you want to go back to them.

- Joe

Ed_Dinning · 26th Aug 2014, 8:06 pm

I used some of the RS ones some time ago, a nice bright light, but looked too "white".
I think my set had the higher value bypass resistor fitted for the lamps.

Ed

paulsherwin · 26th Aug 2014, 9:02 pm

Yellow LEDs look better than white ones in vintage equipment.

As Joe says, the built in lens will cause problems even with wide diffusion LEDs. Filing the lens flat is one solution, or you can glue a diffuser to the end made from a bit of old plastic bottle.

Alistair D · 26th Aug 2014, 9:26 pm

Many Ebay LED sellers now also do warm white LEDs.

Joe, interesting you say that about filing the top of the LED flat. The ones I am currently using are already flat topped. They are around 1500mCD ad have a viewing angle of around 140 degrees. I converted an old FRG 7000 receiver to LEDs. Yes they are a bit white but the light output at 15mA is better than the original bulbs.

Al

26th Aug 2014, 3:07 pm	#1
Scottart Pentode Join Date: Apr 2005 Location: London, UK. Posts: 205	DAC90A LED Bulbs ? I've purchased a couple of these to experiment with as alternatives to the standard 'dim' scale lamps in a Bush DAC90A : http://spiratronics.com/6v-white-led-mes-bulb-100a.html http://www.spiratronics.com/data/2530.pdf Has any one tried these, and what ( if any ? ) circuit adjustments are required - I'll wire them in series, and assume the 75 ohm parallel resistor ( R16) will need changing. I 'read' these LEDs can be used on 6V AC as well as DC - operating current 20ma each at 6v. Don't want to do any 'major surgery' to the radio, just wonder if this could be a useful 'minor' upgrade Thanks, Stephen

26th Aug 2014, 5:01 pm	#2
ThePillenwerfer Octode Join Date: Mar 2011 Location: Sheffield, South Yorkshire, UK. Posts: 1,453	Re: DAC90A LED Bulbs ? I've made my own LED lamps by re-using old MES caps, see below. After taking the photo I discovered that they work much better if you file the top of the LEDs flat. No modifications to the set required beyond checking the connections to the lamp-holders. If they do need changing it won't affect the operation of standard lamps if you want to go back to them. - Joe Attached Thumbnails __________________ "Experts are only good at one thing: explaining why something will not work!" Last edited by ThePillenwerfer; 26th Aug 2014 at 5:08 pm. Reason: Additional information.

26th Aug 2014, 8:06 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: DAC90A LED Bulbs ? I used some of the RS ones some time ago, a nice bright light, but looked too "white". I think my set had the higher value bypass resistor fitted for the lamps. Ed

26th Aug 2014, 9:02 pm	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: DAC90A LED Bulbs ? Yellow LEDs look better than white ones in vintage equipment. As Joe says, the built in lens will cause problems even with wide diffusion LEDs. Filing the lens flat is one solution, or you can glue a diffuser to the end made from a bit of old plastic bottle.

26th Aug 2014, 9:26 pm	#5
Alistair D Nonode Join Date: Jan 2010 Location: Edinburgh, UK. Posts: 2,008	Re: DAC90A LED Bulbs ? Many Ebay LED sellers now also do warm white LEDs. Joe, interesting you say that about filing the top of the LED flat. The ones I am currently using are already flat topped. They are around 1500mCD ad have a viewing angle of around 140 degrees. I converted an old FRG 7000 receiver to LEDs. Yes they are a bit white but the light output at 15mA is better than the original bulbs. Al __________________ I won't tell you how I discovered that.