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Discussion Starter · #1 ·
Hi,

I recently bought a Scalextric Challenger from eBay (it was sold as faulty so no surprises).

Initially the car just sat there on the track with the lights flashing (first normally and then speeding up indicating a fault) - I'd checked all the suggestions I'd found on the internet by now.

I took the car apart and removed the main PCB from the Challenger unit:



I turned it over and discovered that one of the surface mount components was partially detached from the board (circled in red in the following image)



Silk screened 'T3' on the PCB and 'A4TAK' on the component (the 'T' has a line above it) I cannot find any info about it on the internet - I can only assume it's a transistor but, as to whether it's NPN, PNP or FET I've no idea.

I soldered the component back onto the PCB and reinstalled it in the car.

Now when the car is placed on the track it takes off at full tilt ignoring the magnet and doesn't slow at all.

My summation is that the transistor(?) is controlling the throttle level of the car and when it was disconnected from the PCB (maybe by going 'pop!') it was open circuit and thereby supplying no power to the motor. When it was reconnected, if it had failed and gone short circuit, it was supplying full power to the motor (hence shooting off at a rapid rate). I've checked the power circuit on the board and that it's supplying 5V from the voltage regulator. I've also checked the reed switch (small glass enclosed component at the top of the PCB in the 2nd image) - it closes when passing over the magnet under the track. I'm assuming that the microcontroller on the board is OK as it's controlling the lights and indicating the fault when open circuit.

Now, the question... Does anyone out there have any idea about this? Any clue as to what the component might be (PNP transistor/NPN transistor/FET). If I can find it i'll swap out for a replacement (or equivalent) and see if that solves the problem.

Failing that does anyone have a Challenger for sale (working set, or working car, or working main PCB)?

Hope that makes sense.

Thanks for reading
 

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Discussion Starter · #3 ·
Hi,

Thanks for that. I'll try PMing RichG and see if he has any idea as to equivalent component.

In the mean time I took the easy way out and bought a replacement Challenger PCB from SlotCity.co.uk - all working fine now!

I'll hang onto the old board and see if it can be repaired.
 

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Like Steve I could not find the device, SMT devices are notoriously difficult to identify. Anything with A4 in came up with a diode which is obviously not correct.

So I resorted to removing the device & checking it. It's an N-Channel Mosfet. Connections as follows.



I would sugest as a starting point using a PMV31XN which is what we came up with as a replecement for the N02 motor driver in the Digital in-car chip. However if that's not available then use that chips spec as a guide and see what else is out there?

The other thing you could do is PM Greg, gmyers2442, and find out what he is using as the N02 replacement these days? He would probably be happy to supply one.

Rich
 
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Steve ...... PM me your address and I'll post a couple of PMV31XN to you.

All the best - Greg
(not to be confused with Greg Myers (gymers))
 

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Discussion Starter · #6 ·
Hi,

Rich - You're a star!

Greg - You're a star too! PM on the way.

Thanks guys for your help, it's greatly appreciated. I'll let you know how it goes.

Beers all round!!

Steve
 

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Steve .... they have been sent by 1st Class post, hope they work.

Thanks for the virtual beer, I virtually enjoyed it
 

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Discussion Starter · #8 ·
You guys are absolute bl*%$y geniuses! It works perfectly!! :)

I just unsoldered the old FET and soldered in one of the replacements that Greg sent me, connected it all back up and away we went - slowly drew up to the magnet, pressed learn and off it went... perfect.

Really grateful guys - much appreciated :)

Steve

P.S. and there wasn't even any swearing soldering the SMD in place! ;-)
 
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