A genuine panel from an Airbus uses 5v bulbs for the backlighting. An original panel for a cockpit project will most likely come from an Aircraft which is over 15-20 years old. It is not unusual for panels from torn down aircraft to have blown bulbs.
When I received the overhead Fire panel more than half the bulbs were completely blown. Replacement of these bulbs did not lead to a satisfactory backlighting — you soon find out the new bulbs overshadow the old bulbs creating a backlight imbalance. Maintenance of the panel will require the replacement of all bulbs.
The Firepanel backlight board has over 30 bulbs — these were all painstakingly replaced by manual soldering. If you are refurbishing panels, you realize you will need hundreds of bulbs if you intend to replace all of them.
Fortunately our friend Holt has pointed out an affordable place to purchase bulbs — memotronics.com – a box of 10 #7152 miniature bead grain wheat bulbs 5v will set you back 5.49 USD.
With traditional bulbs you will require a high level of current to operate. The Fire panel itself requires 3.8 Amps (!).
The end result, well worth the effort:
Hi Ben, the backlight imbalance created with the old/new bulbs was probably because the old bulbs where 60mA, 0.3W bulbs! That means they are about half bright relative to 115mA, 0.6W bulbs used in other panels.
On the overhead the 60mA bulbs are found on FIRE and ADIRS panels which are non Sirio panels.
Hi Simon, you are right as usual! After careful measurements of the original bulbs they are indeed 68 mA or half the amp of the other bulbs. The panel almost seems too bright in complete darkness and of course will get hot quickly. Next time I will consult with you first! Sometime i will need to replace these bulbs yet again…
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Were you able to get the proper 60mA, 0.3W bulbs from the same source you mentioned previously? I just picked up a FIRE panel for myself and I’m definitely not keen on burning anything out! Thanks for the warning!
Hi Ted, yes, bulbs #680 were the bulbs I used. http://www.memotronics.com/box-of-10-680-miniature-bead-grain-of-wheat-bulbs-new/
Thanks! Those little bulbs are a devil to hold in place while soldering. Although once you’ve done a few dozen, I expect it comes more naturally.