On a New York City subway car, the tail lights are 37.5 vdc. I have one which reads 36.5 vdc, and every bulb installed, does a slow (about 2 seconds) burn. It doesn’t pop instantaneously, but rather smokes and burns out.
Any ideas?
When you say "every bulb installed" do you mean the entire car? Multiple cars? Or just one socket on one car?
What I'm getting at is if you have a bad connection, you may read line voltage until you put the load on it. Then a bad connection results in voltage drop and there's your sign.
Is it in series with something else? A shunting resistor gone bad?
They are not in series and no resistor.
When you say "every bulb installed" do you mean the entire car? Multiple cars? Or just one socket on one car?
Every bulb that I installed in that particular socket.
This. Did you measure the voltage at the socket?
Yes, measured the voltage at the socket.
If a bulb comes on and then burns out it usually means there is an air leak in the bulb-- no vacuum -- thus the bulb burns hot and dies quickly.
I thought that too, a leak, but every one?
If a bulb comes on and then burns out it usually means there is an air leak in the bulb-- no vacuum -- thus the bulb burns hot and dies quickly.
I thought that too, a leak, but every one?
i'am going with Dennis on this one.
Smoke in a bulb is usually caused by air
So my guess is you have a run of defective bulbs
the term is they have gone soft !
if it was a over voltage problem then they would just burn out
not usual to get smoke.
smoke = air
air is bad !
:vs_cool:
1. What voltage are the bulbs rated for?
2. What should the voltage be?
3. This can't be the first time there has been this sort of issue talk to the old timers.
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