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QUOTE Has anyone got a picture of the light board showing the components and how they are connected?

Here you are Rich. This is/was the light board of my DBR9. Both lights failed after very little running, and then some very life-like smoke issued from the bonnet vents!!

cheers,

Rob

 

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No measurements for you Rich, but possibly interesting info. I've just been fiddling about with the DBR9, and applied 3v directly to the legs of the LEDs - both work! So the transistor has failed, disabling the lights, but the actual LEDs are undamaged.

One leg of one LED was loose, so that 'failure' was probably down to poor assembly rather than component failure. (Might be worth checking yours, Kev?)

So what do I need to make my lights work properly again?

cheers,

Rob

 

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Steve A, you can check the LEDs by putting a low voltage (3V) across the LED legs.

I'm not sure about repairing the board, it looks very tight and I'm not sure my soldering skills are up the job (my DBR9 blew its lights too). I've ordered an overdrive XDS kit instead, so hopefully I'll be able to get the lights working again, and they'll be permanent.

Another thought too, really as a preventative measure to try to stop this happening again in the future. Would it be possible/ make sense to put a resistor in before the board? If the lighting board is only getting 12v then hopefully the circuit will survive. Can someone advise on values?

cheers,

Rob

 

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So Rich, is there an easy fix that us mere mortals can use?

I put the meter across my scaley-powered track and got 16v, even 16.5v, at full throttle. Would a resistor placed before the light board work to protect it? Or does it need a more in-depth fix? I think fixing blown boards is probably beyond most of us, but if there's a relatively simple way of preventing it happening we'd appreciate it.

I just bought the SCX C6R, great car, really good fun to drive. But the lights lasted 4 laps and then went 'pop'!

cheers,

Rob

 

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Thanks Rich

I've now got three SCX cars with blown front light boards

so I've been playing around with some LEDs and resistors, trying to find a cheap fix.

I had no intention of trying to repair or modify the boards, so I just removed the intact LEDs and binned the rest. I left the rear boards alone.

The LEDs I bought are rated at 3.3v, 20-30mA. I'd previously recorded a peak of 16.5v at the track from Scaley wall warts, so I did some maths (well MS Excel did the maths!) and came up with 330 ohms for 30mA or 495 ohms for 20mA needed for two LEDs in series.

The LEDs came with 470 ohm resistors so they seemed like a good starting point. I soldered the resistor to the +ve leg of one LED, then soldered the +ve of the second LED to the -ve of the first. This 'circuit' was then attached to the existing copper tabs in the body. I did my Vette and F360 like this. I also found some 560 ohm resistors, so I fitted one of those to my DBR9.

The 560 ohm resistor was a mistake. Running the DBR with no load the lights work fine, but on the track they're hardly coming on at all even at full throttle.

I did about 70 laps tonight with the C6R and it's been great, and it still works! So my cheap 'n' cheerful effort has so far lasted nearly 20 times longer than the original SCX board!

The lights come on from about 1/3 throttle, gradually getting brighter with more power.

I did about 30 or 40 laps with the Ferrari and that too was fine. But, and here's the rub, it's very easy to damage the circuit. I put the Ferrari on the other lane, forgetting that I'd reversed the track power. About a second of going in reverse, and suddenly only one LED works. Oops!

So I've got some repairs to do, but I'm pleased with the results. I just need to remember to put the cars on the track the right way! The LEDs weren't expensive, £4.45 inc post for 10 LEDs and resistors from an ebay seller.

No pics yet, but I'll post some if you want 'em.

cheers,

Rob

 

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Ok, you asked...

Sorry Kev, I haven't got any LEDs left but here's the link to the seller

Rich, thanks for the diode advice

What sort of diode am I looking for? Just had a quick look on ebay and I am LOST!!

Wouldn't the diode cause a voltage drop and thus affect the resistor calcs though?

cheers,

Rob

 

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Thanks Kev, much appreciated

And thanks for the calcs Rich. The voltage drop would seem give the LEDs a bit of a safety margin too, which has to be better.

cheers,

Rob

 

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The latest stage of this little saga - on Rich's advice Zipp bought some diodes, and cos he's a nice guy he sent me some! Thanks again mate

So I had to try a couple out, didn't I? Here they are fitted to the Vette and 360. I put the arrows in cos the diodes are tiny

I haven't tried them on the track yet, but the lights work fine at 9-12v, and nothing went pop when I reversed the current so I think that's a successful test!

Total component cost is under £1 per car, so I think I'm going to be adding lights to a few more!
Rich, we need a capacitor next so we can have permanent lights

cheers,

Rob

 

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Here you go -

Replacement lights
3mm white LEDs
470 ohm resistors
1N4001, 1N914 or 1N4148 diodes

I bought my LEDs here, he supplies them with the correct resistors too.

Try here for the diodes

The 'preventative' resistors are 100ohm, the first seller lists them as well.

For permanent lights try the excellent Overdrive kits, from Pendle, MRE etc

cheers,

Rob

 

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All the relevant bits (I hope) are in the Resources section here

cheers,

Rob