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Discussion Starter · #1 ·
Hi I recently fitted 2 C8515 chips to a pair of Mclaren MP4's the Jenson and Lewis versions. Both ran fine for a while, but now the both have failed with blown chips.
I am using the SCALEXTRIC Digital Bundle SL6 Pitlane 2021 - 4 Cars ARC PRO JadlamRacing Layout, and the C8515 also from Jadlam, not sure if they are G or H rev, they are definitely not F rev.

one car runs continually and Q2 is blown, the other does not run and Q1 is blown, does any one have a schematic drawing showing the part types fitted so i can repair it.
Q1 is marked R1, this may be a PNP transistor, and Q2 is marked 34N this may be a DMN3404L n-channel FET.

Both CARS have 2 of the Ferrite Men fitted, (one on motor and one on pickup),and have lights wired across the motor. So any ideas what caused the failures, should I move the lights to the 4 empty connector pins, to reduce the load on motor drive components.
Circuit component Passive circuit component Hardware programmer Electronic engineering Electronic component
Passive circuit component Circuit component Hardware programmer Computer hardware Electronic engineering
Circuit component Passive circuit component Hardware programmer Electronic engineering Electronic component

Passive circuit component Circuit component Hardware programmer Computer hardware Electronic engineering
 

Digital Guru
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Rikorocket on this forum may be able to supply part numbers for you 馃憤馃徏.

But I would seriously look into what is causing the chips to blow, yes they can be repaired but usually each subsequent repair leaves less copper track to bed onto which then renders the chip scrap 馃槓
 

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These were my suggestions to Scalextric that they used to make the Slot.it compatible Rev H chip:

The changes to make a high power capable (still works with standard cars) DPR chip are:

D1 to D4 use B340LA-13-F, Schottky Diode, 3A max, 40V, 2-Pin, SMA RS part number 738-4780

TR1 use PMV31XN,215, N-channel MOSFET Transistor 5.9 A 20 V, 3-Pin TO-236AB RS part number 725-8335 [this should be Q1]

TR2 use IRLML6402TRPBF, P-channel MOSFET Transistor 3.7 A 20 V, 3-Pin SOT-2 RS part number 301-322 [this should be Q2]
 

Rich Dumas
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The chips are burning out because the cars are pulling too many amps. If you had a power supply with an amp meter built in you could confirm that by connecting directly to the motor of each car. At 12 volts a Scalextric 18K motor will pull about 0.2 amps. A common problem with many of the motors used in 1/32nd cars is that as they are breaking in dust from the brushes gets caught in the commutator slots and causes a short ciricuit, which will greatly increase the current draw.
 

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The chips you have blown are capable of taking nigh on the whole of a powerbase current on their own. So as RichD says I would suspect there is a fault, maybe a shorting in those particular cars. That could be internal motor or the wiring on top of the motor...
 

Premium Member
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Rikorocket on this forum may be able to supply part numbers for you 馃憤馃徏.

But I would seriously look into what is causing the chips to blow, yes they can be repaired but usually each subsequent repair leaves less copper track to bed onto which then renders the chip scrap 馃槓
Unfortunately, the only person I know of who could have repaired chips is Greg K and since Covid, has sadly been absent from this Forum.
 

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Discussion Starter · #7 ·
The chips are burning out because the cars are pulling too many amps. If you had a power supply with an amp meter built in you could confirm that by connecting directly to the motor of each car. At 12 volts a Scalextric 18K motor will pull about 0.2 amps. A common problem with many of the motors used in 1/32nd cars is that as they are breaking in dust from the brushes gets caught in the commutator slots and causes a short ciricuit, which will greatly increase the current draw.
You are quire correct the motors draw far too much current, one measures 3ohm and the other 4.4ohm, i have attached a picture of the motor, where is the best place to source these, they seam to be glued in, is this original, or have they been replaced once before, i bought these as used once on ebay, as analog, i added the chips.
Gas Automotive tire Electrical wiring Machine Auto part

These were my suggestions to Scalextric that they used to make the Slot.it compatible Rev H chip:

The changes to make a high power capable (still works with standard cars) DPR chip are:

D1 to D4 use B340LA-13-F, Schottky Diode, 3A max, 40V, 2-Pin, SMA RS part number 738-4780

TR1 use PMV31XN,215, N-channel MOSFET Transistor 5.9 A 20 V, 3-Pin TO-236AB RS part number 725-8335 [this should be Q1]

TR2 use IRLML6402TRPBF, P-channel MOSFET Transistor 3.7 A 20 V, 3-Pin SOT-2 RS part number 301-322 [this should be Q2]
Thanks for this info, i found the TR1 & TR2 types mentioned now obsolete, so have ordered IRLM0030TRPBF & AO3401 devices instead from China as i could not find UK stock, i will let you know how they go when i have replaced them and the motors which are the cause of the issue.
 

Rich Dumas
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4,139 Posts
A regular "18K" Scalextric motor should read 5.1 ohms across all three poles. You have to take the motor apart to do the readings, readings taken across the motor leads are not likely to make sense. The markings on the motor that you have indicate that is a generic motor, those are often sold on ebay, stock Scalextric motors never have printed markings, but they usually have a black stripe across the top of the endbell. The first thing to try is to spray some electrical contact cleaner on to the commutator while the motor is running at ~6 volts, with a little luck that will remove any dust that is stuck in the commutator slots. If that fails you could take the motor apart and scrape out the slots with some thin, stiff plastic.
It would probably be less trouble to buy stock replacement motors.
 

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Discussion Starter · #9 ·
A regular "18K" Scalextric motor should read 5.1 ohms across all three poles. You have to take the motor apart to do the readings, readings taken across the motor leads are not likely to make sense. The markings on the motor that you have indicate that is a generic motor, those are often sold on ebay, stock Scalextric motors never have printed markings, but they usually have a black stripe across the top of the endbell. The first thing to try is to spray some electrical contact cleaner on to the commutator while the motor is running at ~6 volts, with a little luck that will remove any dust that is stuck in the commutator slots. If that fails you could take the motor apart and scrape out the slots with some thin, stiff plastic.
It would probably be less trouble to buy stock replacement motors.
Thanks, I had to strip motor down and clean out the slots in commutator, and now it runs at 12v and draws 150mA, instead of several Amps. I will get a stock of spare motors, for a quicker repair, as these look to be trouble in the long run, are these Scalextric brand new 22000 RPM sidewinder short shaft car motor SUPERB spares | eBay any good? or is it best to get them somewhere else.
 
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