Illumination Bulbs for Armstrong 624 Tuner

Discussion in 'Tuners' started by Multimode, Jan 1, 2018.

  1. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    A happy new year to all AK-ers!

    I used an Armstrong 624 FM tuner for about 30 years until moving to internet radio and have now brought it out of storage. I won't be using it again but someone else will enjoy it so I want to make sure all works as it should.

    Not long before I stopped using it a couple of the illumination bulbs blew. The ones that still work also look ready to fail so I want to replace them all, however I can't see any wattage rating on them. The schematic shows 11.5 V supply, so I assume that the bulbs will be 12 Volt. Two are screw-in and two are wedge-type (capless).

    Please can anyone tell me the wattage of these bulbs, and perhaps a UK source?
     
  2. restorer-john

    restorer-john Super Member

    Messages:
    4,558
    Location:
    Australia
  3. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    Thanks, John. That's where I found a schematic showing the supply voltage, but there's no mention of the wattage.

    I've followed Jim Lesurf's articles and forum contributions on Armstrong and on electronics in general for some time, with great interest.
     
    Last edited: Jan 1, 2018
  4. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    Oops! The 11.5 Volt feed that I quoted was from a schematic for the 600 Series receivers but I've now found a schematic for the tuners showing 10 Volts. Presumably I still need to be looking for bulbs rated at 12 Volts.
     
  5. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    A small step forward...

    I've found a faint "12-15/1 OS" etched on one of the capless bulbs. Please can anyone here interpret?
     
  6. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    41,419
    Location:
    Hertfordshire, UK
    Yes, I think so. (quite normal to under-run bulbs like this so they have a longer life, 10V supply --> 12V bulb = under-run).
    Hard to say (not that I am an expert in these matters), could mean 12-15V? :dunno:

    Can you post a picture? - so we know what they physically look like. ;)
     
    Multimode likes this.
  7. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    The wedge bulbs are the type shown on http://cpc.farnell.com/c/electrical...miniature-filament-bulbs?lamp-base-type=wedge
    I've found some screw ones in the carcass of a Armstrong receiver that my son had discarded, and the wattage can be read on them so they no longer present a problem. The wedge bulbs in that carcass are unfortunately dead and with no wattage marking visible.
     
  8. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    41,419
    Location:
    Hertfordshire, UK
  9. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    The first ones look useful. My ‘gut feeling’ has been for 1.2W - I found some elsewhere but in packs of 100. I suspect 2W is more for car instruments.

    I’ve been in direct touch with Jim Lesurf. He has no info on the wattage and said he used a small LED with a resistor in series when his needed replacement. That’s a bit adventurous for this amateur so I’ll stay with the original.
     
  10. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    I fitted 1.2W bulbs and they are perfect. They needed to be quite long, 18mm, and took a bit of finding. I was fortunate to get them from an eBay automotive bulb retailer at £1.49 for the pair including next-day delivery!
     
    Hyperion likes this.
  11. restorer-john

    restorer-john Super Member

    Messages:
    4,558
    Location:
    Australia
    Well done, it looks like you have solved the mystery globe issue.

    :)
     
    Multimode and Hyperion like this.
  12. Multimode

    Multimode Member

    Messages:
    79
    Location:
    Cambridgeshire, UK
    I tested the tuner this morning via the Sansui AU-919 amplifier. Digital streaming from my Cambridge CXN network player gives better sound quality, as well as a much wider choice of broadcast source of course, but the Armstrong tuner does a really good job for what it is.

    Thanks for the advice re: the bulbs, and I hope I've helped someone in turn by identifying their ratings and type. (The two screw bulbs are 12V, 1.5W LES type and, as said, the two push-ins are 12V, 1.2W wedge/capless type, 18mm long).
     
    Last edited: Jan 7, 2018
    Hyperion likes this.

Share This Page