Standlights stopped working

On Thu, 13 Feb 2003 19:01:22 +0100, contributor King Pineapple had scribed:

Quoted message said:

Suddenly both front and rear standlights on my bike have stopped working. (I'm not sure if that is
the right term in English - called Standlichts in German - the little diodes that stay on with
dynamo lights when you stop pedalling). Anyway, does anybody know what the problem could be? It
happened once before and I think it is something to do with incorrect polarity or earthing, but
although I fixed it last time I can no longer remember what I did! Any suggestions appreciated.

When were they previously used, if it is more than a week then the condenser takes a little longer
to provide the necessary power to the LEDs as power is drawn into the condenser. Does the front
light incandescent bulb light up when you start to move? If so it is likely to be as suggested, if
not check all wiring there is likely to be a break somewhere.

Gary

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Thu, 03 Apr 2003 12:21:14 +0100, Gary Knighton:

Quoted message said:

On Thu, 13 Feb 2003 19:01:22 +0100, contributor King Pineapple had scribed:

Quoted message said:

Suddenly both front and rear standlights on my bike have stopped working. (I'm not sure if that
is the right term in English - called Standlichts in German - the little diodes that stay on with
dynamo lights when you stop pedalling). Anyway, does anybody know what the problem could be?

I presume the halogen bulb is old (> 60 hours of use) an neighboured windings of the filament are
welded together. This caused the resistance of the bulb to decrease.

Usual dynamos behave like current sources (current won't exceed 550 mA). With a lower resistance of
the headlamp bulb the voltage of the whole light system is lower then it should be. With enough
welds in the bulb the voltage might decrease from 6.0-6.5 Volt down to lower than 5 Volt even at
high speed. What might not be noticed from the headlamp beam is easily noticed from the Standlights:
With voltages lower than 4.5 Volt the capacitor(s) won't be charged!

Solution: Use a new halogen bulb! Mount the headlamp where it gets the least vibration - especially
NOT at the unsuspended part of suspension fork.

If you like to experiment: Compare the filaments of the old and the new bulb under a stron
magnifying glass and measure the voltage when supplied with 400mA (increase the current slowly from
lower values).

Andreas (just had the same diagnosis on a friends bike this morning)