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Old Jan 22nd, 2020, 18:51   #5
pinballdave
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Quote:
Originally Posted by rxtian View Post
As far as I can reason, the housing is designed to accomadate the heat output of the bulb, and I don't think the LED is going to put out more heat.
While this is true, it's not the full story.

It is correct that a typical filament bulb is not very efficient and the majority of the energy (80-90%) put into the bulb is given off in heat, so an LED bulb (even with a 'CAN-BUS' resistor) will invariably produce less heat.

What is different is the distribution of that heat. A filament bulb distributes most of the heat evenly across the surface of the glass bulb which is radiated away in all directions in the same way that happens with the light it produces (as a lot of the heat energy produced is infra-red light). So the reflectors for the light, will also reflect the heat away from the parts of the bulb holder that may be damaged by it.

An LED does not have a glass bulb, and is usually built on a ceramic substrate/PCB which conducts the heat away via the bulb holder terminals. So while there is less heat produced overall, a poorly designed LED can conduct more heat to the bulb terminals than the filament bulb it replaces and can cause the terminals to overheat and melt.

To the original poster, if you're worried about whether you need a 'can-bus' LED or not, simply remove the bulb in question, and see if any warnings are generated. If there are no warnings, then you should be fine with a good quality LED without the extra resistor.

I'd be very cautious about using an LED with an extra resistor, unless you are certain that the bulb holder can handle it. I'd also be careful about the brightness of the replacement LEDs, don't get carried away thinking brighter is better. Something that is 2x or 3x the brightness level of a filament bulb will usually be fine, but the brighter the LED, the more heat is produced.
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