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New and a little confused

4382 Views 34 Replies 10 Participants Last post by  GregK
Hi all Im about to purchase a Scalextric set but dont know which one Digital or ARC. Almost does the additional track you can purchase 1:32 work on either. Does anyone have some suggestions where to purchase as a bundle in Australia or anywhere that will will ship as a reasonable price.

Thanks all in advance
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Its very likely the smoke you saw was the moment that the drive circuit failed which powers the motor. Normally they fail as open circuit so then the motor doesnt function at all. Sometimes they fail as a short circuit in which case the motor is from then onwards powered regardless of throttle position... one particular device is usually at fault (N02), but if the brake circuit is activated when this fail mode is presentthen P03 will be damaged too.

GregK is expert at carrying out these repairs...

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Why did it fail? good question...
1/ with the body off any chance something shorted out as it deslotted?
2/ could the capacitor on the motor have temporarily shorted out?
3/ is there any chance the motor has a shorted winding? does it run at full power with the standard DPR analog blanking plate/socket?
4/ any chance the motor was overloaded during your trials? e.g. wheels locked at full power?

All just thoughts...

Sorry to hear your update... hope all goes well and with all good wishes from me...

Meanwhile sounds like the simple answer is simply to replace the decoder... however, if you want to explore the failed chip in more detail... which I personally enjoy doing... happy to offer further ideas and input... and sorry to ask... but could you remind me please... do you have a digital multimeter which can be used to measure resistance?

Take care,

Could we double check please... when you ran the car manually through the lane changer... was track power turned on and the car held parallel with the track so the IR LED lines up with the LC sensor? also, wondering if you had disconnected the motor to avoid wheels spinning while you did this test. I am a bit surprised that the chip is not driving the IR LED correctly.

The multimeter will be useful for next steps... and the photo will really help too...

@John, while deciding which way to go... between diagnose, post or bin...

Are you familiar with using the test meter as a simple continuity tester...


1/ make sure probes are connected black to COMM terminal and red to the terminal with ohm symbol (on the right)

2/ rotate dial one click counter-clockwise from photo setting.... to get to the combined diode and beeper symbol.

3/ touch probes together and the beeper should be triggered... does this happen?

Sorry if this is too obvious... but is it working as a continuity tester?

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ok... so the IR LED is running which means the microcontroller is running too. This takes us back to normal failure territory... suspects are the n-channel motor drive MOSFET and the p-channel brake drive MOSFET. Replacing these requires careful manipulation of very small surface mount devices...

When the motor drive MOSFET fails short circuit it will cause damage to the brake drive MOSFET as they should never both be turned on at the same time. Should be any easy fix for GregK... if postage makes sense...

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