|Son hubdynamo's are extremely
reliable, but problems could occur. With these pointers you should be
to identify and rectify most problems
Usually the fault lies with
the wiring, not the dynamo. Just as with any other lighting setup a
search helps. Disconnect the rear light first, if the headlight now
normally, you have probably swapped the leads to the rearlight causing
If this doesn't work remove
the leads from the dynamo. Give the wheel a spin and shortcircuit the
with a coin or key. If you get sparks and the wheels slows down
the hub is ok.
Reconnect the wiring and
spin the wheel again. If flipping the switch doesn't do anything you
an open circuit (look for blown bulbs or broken connectors), if the
slows down as short circuited on one or both positions of the switch
again have a short circuit (incorrect wiring, frayed cables).
If the dynamo fails to deliver
current (easily checked by giving the wheel a spin and shortcircuiting
the terminals with a screwdriver: sparks should be visible) the
wiring in the dynamo could be faulty. This can be damaged if some moron
er.. ill advised individual tries to adjust the non-adjustable
or by riding around with a loose skewer. This is has to be repaired by
a SON approved technician (eg the importer of factory)
Most frequent mistake is
putting the black switchring back on reversed. The magnet won't reach
the reedswitch and the light will remain dark.
With the E6 it is possible
for the central contact-spring to short circuit against the spring
the bulb in place in the reflector. My guess is this can happen when
bulb slips out of the reflector during insertion. Carefully bend the
back with a ballpoint refill or similar.
No front light (classic
round Lumotec only):
The contact-lip (which contacts
the back of the bulb) could be bent backwards. This can happen if you
the light frequently with the mounting screw done up tight. To fix open
the Lumotec, remove the coil spring, bend the central contact
a few millimeters and reassamble. Stop readjusting the angle of the
or loosen the screw first.
Bulbs only have a lifespan
of around 100 hours (a household bulb = 2000-3000hrs!) With age the
could weld together and short out, which decreases the light emitting
Replace the bulb for full power.
No rear light
The Son has no connection
to earth. If you use single wiring to the rear light the returnpath is
made up by the connection through the frame to the front light. Ensure
that both components are securely connected to the frame.
No front and rear light
Lights usually have a connection
to earth. If you use double wiring to connect the rear light to the
do not get the wires mixed up. If you connect the wires crosswise, the
dynamo will be shortcircuited.
Frequent front bulb failure.
Mean time to failure for
a bulb is around 100 hrs, and even less (30-50) for the fast crowd. If
you ride a lot that could mean several bulbs a year. If the bulbs fail
a lot sooner, a failed or disconnected Z-diode is usually the culprit.
With old Lumotecs the diode sometimes makes poor contact, with the
Senso the diode could melt its connection to the circuitboard.
If you use a headlight only,
without connecting a rear light, change the bulb to one rated 3 watts.
Fitting the headlight to
the unsuspended part of a suspensionfork is very hard on the filament
will shorten bulblife.
Irregular & spotted beam
This is usually caused by faults of the filament. With old bulbs the
winding could have shortcircuited, causing irregular lighting. With
cheap bulbs the filamentposition could be out of specification, moving
the light source out of focus
The properly defined filament is on the left, the 'cheap' bulb is on
the right. Note the much more widely spaced filament windings
Rear light bulb failure
This is usually caused by
the high voltage caused by a failed frontlight together with a
Z-diode. Check the headlight if this happens.
Rear light goes on late
or not at all
A frontbulb with shortened
windings has a lower resistance, causing the voltage to drop (the
is a currentsource) If the voltage is too low LED lights with
will not function well. Replace the front bulb to restore light at both
Newly installed bearings
have zero play. With use the axial and radial play could increase to
This will result in approx. 0.2 mm sideplay at the rimface. This cannot
be adjusted out and is normal for this kind of bearing. If you find a
more play the bearings are probably damaged and you should return the
for service. Never try to adjust the bearings, you'll only succeed
in severing the electrical connections and voiding the guarantee!
These are usually caused
by an unsufficiently tightened skewer. Check that the OLD of the fork
100 mm (XS excepted), and that the dropouts are parallel and that the
skewer is really tight
Irregular grinding noises
This could be caused by
sand in the labirinth seal, or a fragment of the very brittle magnets
around in the hub. This isn't critical and should disappear with
Regular grinding noises,
difficult turning or locked axle.
This could be caused by
a locked dynamo, not by bearing failure. The interior is well sealed.
-salt-water manages to find it's way inside, it won't come out easily.
Thus the hub could freeze solid, or rust particles could get jammed in
the narrow crevice between stator and rotor. Do not keep riding this
but send it in for service.
SON's old type (with black centersection
prior to '99)
We have never imported this
type which needs to be unspoked from the wheel before it can be
Son guaranteed the hub for three years after purchase, but it can be
in just like the others for service.
This also applies to the
hubgenerators Wing 1,2 en 3 by Union and Marwi: these are based on a
design by and can also be