dial bulb replacement

jmcilkley

Member
2019-10-10 10:43 pm
While restoring an Akai AS-980 I have been investigating the best way of replacing the various types of light bulbs in the receiver. The first ones to deal with were the ubiquitous fuse lamps - they look like a fuse but are actually bulbs. I saw on ebay that they are hard to find and led ones would be a better bet. It all depends what voltage you need. Some equipment uses 6.3v, some 8v and the Akai is 10v (except the tuner dial illumination which was 5 x 8v ac). There are a few suppliers in USA and Germany who supply special 6.3 and 8v ones, but at quite a high price. I also discovered that these give a light that is often too bright and it is suggested the bulb is installed backwards to reduce the brightness! I tried a standard 12v one as is sold for car courtesy lights and at 10v they work perfectly and they cost about £2.50 for 10 if you buy direct from China. I changed the the 8v ac to the tuner dial and wired in the 10v dc instead. The lower power for all bulbs should actually reduce the total load anyway.
I did also try little led bulbs that run off 3v and cost even less, just a few pence each. Soldering a short wire to each side meant they were pretty easy to install, soldering the wires to the fuseholder connections. The brightness was perfect but you have to provide a 3v supply which can be achieved with a tiny module available from China for less than £1. This will take any dc voltage and either boost it up or reduce it to the level you want. This little device would allow you to also use the 12v fuse lamp bulbs by boosting the 8v or 6.3v to 10v.
The indicators to show the input selected etc. (13 of them on my Akai!) were a tiny bulb that also ran off the 10v. I first tried using 3mm led's which physically fitted perfectly but needed a suitable resistor to drop the voltage down to 3v. This worked well with about 380 ohms but was a bit fiddly to make up with shrink tubing as well. Then I discovered that you can buy them on ebay ready made up with leads and a resistor. At 10v they are a bit bright but for an 8v supply they would be fine.
If your dial lights run off ac then you can also buy very cheap ac to dc converters with the output voltage variable - also very cheap.
These options allow you to convert any equipment to led for a very low cost. I'm really pleased with my results.
 

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abanico

Member
2009-10-06 1:52 am
If you look at the component sellers catalogs like Mouser and others, search for incandescent bulbs, wire terminated . Two thin wires are coming from the bulb.6,12 or 24 v to choose , are cheap and some are 20000h rated . About 20 ma. Light is more pleasant and the right one for a vintage gear .There is also the possibility to make series and work the same on AC or DC.