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Discussion Starter · #1 ·
I bought a MRSLOTCAR MR1045 (McLaren F1 GTR) and a Scalextric C7005 chip, which seems to be the only non-plug-connector chip available.

I wired it correctly, but something is wrong. In digital mode, the motor doesn't spin very fast at all and the chip goes dead after about 10 seconds of constant throttle. It will work again if pulled from the track and put back, so somehow the chip seems to be deciding to just shut down.

In analog mode, it doesn't shut down but it doesn't go any faster either.

It is wired correctly and the connections are good as far as I can tell. It pairs to a controller correctly, does lane changes correctly, but just will not go any significant speed. The motor, as per its casing label, is 21.5k rpm, 12 V, and 0.28 Amps. As I understand it, this is not a lot of current and I shouldn't have any problem using the C7005 with this motor.

Things I have tried:

  • I have two brand new C7005's, so I tried the other one, got the same result.
  • I tested the motor independently, desoldered from the circuit, by touching its leads to the track in analog mode and it works fine.
  • I tried the C7005 on the track directly with just the engine attached to remove any mechanical issues, same bad result.

My first question is should this combination even work? And if so, what could be wrong?
 

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Hi,

Do you have other cars chipped with the C7005 running fine? Does the car have a magnet?

Might be a faulty motor or a short somewhere in the track or motor. Try the car on the powerbase track piece detached from the track.

If you have a multimeter you could check the DC voltage across the motor terminals at full throttle - it should be around 13 volts.
 

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Do you have a Ferrite-Man fitted across the motor terminals? ........ these are of critical importance on a C7005 chip ... ;)
 

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Discussion Starter · #4 ·
Hi,
Do you have other cars chipped with the C7005 running fine? Does the car have a magnet?

Might be a faulty motor or a short somewhere in the track or motor. Try the car on the powerbase track piece detached from the track.

If you have a multimeter you could check the DC voltage across the motor terminals at full throttle - it should be around 13 volts.
As I said, the motor works fine by itself, connected to the track in analog mode. Other cars are fine. I ended up putting one of the two c7005's into a slot.it car instead and it works fine.
 

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Discussion Starter · #5 ·
Do you have a Ferrite-Man fitted across the motor terminals? ........ these are of critical importance on a C7005 chip ... ;)
Well as-delivered the ferrite-man was between the guide leads near the end so I did not move it.

I put one of the two chips I tested into a new slot.it car and it works fine there. I seem to have a new problem though now, I think I burned out the remaining chip, it suddenly started driving the motor full throttle which made me very happy until I realized it wouldn't slow down or stop! In either analog or digital mode it just goes full throttle constantly if connected. Other cars are fine, from what I've read this symptom means I caused something to be shorted. Is there a way to fix it?
 

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Is the MrSlotCar McLaren still running the original boxer motor? Are you running with traction magnets in the car?

The original boxer motor has a pretty big current draw, power is 21,500 rpm and 300 g/cm torque = 16.13 watts output. = 1.35 amps current draw at stall/start

That may be beyond the power handling capabilities of the 7005 chip, which was designed to fit into the F1 cars with a ff050 motor having about an 8 watt output.

The Slot.it chip for SSD came about partly because the Scalex chips weren't able to handle the power of their boxer motors which are similar power to the MR Slotcar boxer.
 

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Discussion Starter · #7 ·
Is the MrSlotCar McLaren still running the original boxer motor? Are you running with traction magnets in the car?

The original boxer motor has a pretty big current draw, power is 21,500 rpm and 300 g/cm torque = 16.13 watts output. = 1.35 amps current draw at stall/start

That may be beyond the power handling capabilities of the 7005 chip, which was designed to fit into the F1 cars with a ff050 motor having about an 8 watt output.

The Slot.it chip for SSD came about partly because the Scalex chips weren't able to handle the power of their boxer motors which are similar power to the MR Slotcar boxer.
Thank you, this is exactly the answer I was looking for to confirm what I suspected. Yes I'm using the original motor, and I forgot about the startup power spike on components like this.

I temporarily wired up one of my C8515's (while still inside another vehicle!) to the motor from the MrSlotCar McLaren and it appears to work perfectly. I also seem to have a Rev H C8515 which I have read can handle a 3 amp current draw, so this should work. I'm in the process of wiring the C8515 into the McLaren now. I don't have any micro jst 4 pin connectors handy so I'm doing a wire-wrap + solder onto the female port pins :) Sure it would be easier to just get a Slot.it SP15B but that wouldn't arrive until next week and I like a soldering challenge :)
 

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A little bit of Digital chip 101 .......

Pulling away from a standing start or trying to power a car up when the driving wheels can not revolve draws the most current. It is in these situations that you will be likely to blow your chip.

Green Circuit component Passive circuit component Hardware programmer Electronic component

The arrowed components are diodes. As standard, they are rated at 1A as shown. These components are used to ensure that the car can run in whichever direction the car is placed in. As an example, Carerra uses a manual switch to achieve the same function. Up-rating these, as in the C8515 Rev-H, with more efficient types can produce another ~10-15% more voltage to the motor which increases the performance of the car. These rarely are damaged but can drop off if they get hot and their solder melts.

Passive circuit component Circuit component Hardware programmer Electronic engineering Microcontroller

The arrowed components here controls the running and the braking function of the car. As fitted, they are sufficient to handle standard Scalextric motors and with a big dollop of luck they will work with hotter motors from other manufacturers. These components are the most frequently damaged when a chip a chip blows.

This link will show a lot more detail about repairing chips ....

This link will show you how to construct a Ferrite Man ....
 

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