conversations on the forum, especially this
it was obvious that some of us were having problems with
the lights on a couple of recent SCX cars - the Corvette
C6R, Ferrari 360 and Aston Martin DBR9.
bunch of us put our heads together to try to figure out
problem seems to be that the light circuit in the SCX
cars can't handle the higher voltage put out by some
track systems, especially Scalextric. Components fail
and the lights stop working. Only the front lights seem
to be affected.
Note: Not all SCX cars use the same lighting board,
so this fix may not work (or be necessary) for all cars.
needed two solutions - a way of repairing cars with
damaged lights, and a way of preventing the lights being
damaged on future purchases.
photo below shows the 'preventative' measure. This only
works for cars with undamaged lights. The positive feed
to the light board has been cut and a 100 ohm resistor
fitted instead. This limits the voltage and should be
enough to protect the circuit board from damage. I say
'should' because although this has been tested and
proven to work, we don't know how well it stands up as a
long term fix.
to Zipp for the pic.)
second job was to try to fix the cars with damaged
lights. The SCX board is very small and delicate, and
replacing components on it is way beyond my level of
some advice (and maths!) regarding resistor values from
RichG I did some experimenting.
some cheap LEDs from an eBay seller. They came with 470
ohm resistors. The calculated value was 495 ohms, so 470
was close enough.
two photos show the simple light circuit fitted to the
Vette and Aston. The resistor is fitted between the
positive feed and the positive side of the first LED.
The negative leg of the first LED is soldered to the
positive of the second LED. The negative from the second
LED is soldered to the negative feed.
works! The lights come on from about 1/3 throttle and
get progressively brighter.
I found out with one of my cars, if you put the car on
the track the wrong way, the lights go pop! So a bit
more work was needed.
advice from Rich lead to the installation of diodes to
protect the circuits. The diode blocks the current if
the car is put on the track the wrong way (you just have
to make sure you install the diode the right way
round!). The diodes also drop the voltage slightly,
which should give the LEDs more of a safety margin.
Despite the voltage drop the 470 ohm resistor is still
the nearest suitable value.
fitted the diodes to all three of my cars, and between
them they have covered somewhere in the region of 1,000
laps to date. The lights on all three still work
diode is arrowed in the pic below)
soldering such small components is quite fiddly, it's
really only a few minutes' work.
total cost of the components mentioned (LEDs, resistor
and diode) works out at less than £1 per car, so it's a
cheap fix as well as a simple one.
also the potential for lighting other makes of cars
again to Rich and Kev, without your help I'd never have
got these cars sorted.
fun, and mind your fingers!
looking forward to more articles
in our SLAP My SlotCar Series.