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Have been meaning to try this for a while. However first a word of warning. Have only modded one of these, seems to work, but there could be problems yet to find. This is not an easy mod to do physically.

This mod can be viewed either as a way of repairing a failed Saloon board or as an upgrade to the output stage. I suspect most failed boards have one or both of the output mosfets failed.

The device I have chosen to fit as a replacement is the one used by Scalextric in the early Powerbase's, the ZXMC3A16D. If two of them were nearly good enough to power 6 cars, one should be well over the top for one.


The output mosfets are the small black devices marked N02 & P03. First these need to be removed. Apply a soldering iron to the two connections on one side & when the solder melts flip up the device with a screwdriver, now desolder the final connection and remove the device.

To fit the device you need to slightly splay pins 1 to 4 in an outward direction to make them fit the four pads marked in red in a row on the picture. Be very careful not to bend the leads too close to the body of the IC and only tweak them just enough to reach the edges of the pads. The 4 Drain connections, pins 5 to 8 are then connected to a piece of tinned copper wire and the ends bent and soldered to the two remaining connections.



So thats it.


Have never been able to find a spec for the P03 & N02 devices. I assume they are mosfets, but have seen Beppe post that they are transistors?

However here is a comparison between this mosfet and the DF2C03 used by Slot.it in their new decoder.



As you can see it compares favourably in all respects.


The disappointing part is that in testing, I modified a Takara module for ease of swapping, the performance seems identical to the original. This is confirmed by on track performance and by measuring the voltage at the motor.

I therefore expect the gain to be with beefier motors and hopefully that it will not expire.

Ideally need a few people to try this and report back. Very little to loose if you have some failed Saloon boards. This will of course also work with the F1 board.

Farnell part nos for the ZXMC3A16D is 756-4953

Rich
 

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Hi Bryan

Thanks for the info on P03 / PDTA114ET

Have had a look at the data sheet and am sceptical as to weather it is the correct device.

P03 is used to short the motor for Braking and N02 to feed the PWM signal to the motor.

I am concerned about the rating which is only 100mA & 150mW.
Also seems strange that the N02 transistor is not listed as they are likely to be a complimentary pair of either transistors or mosfets.

I think I found this data or similar a year ago when trying to track down P03 & N02 however my memory is failing me. Looking at my scribbles on the sheet that I roughed out the circuit diagram I think I came to the conclusion that the X reference was wrong and that the transistor is an A03. However as I say it is scribble.


Also seems odd to me that they would not use a mosfet in this application. Equally odd that I am getting identical performance after grafting in a mosfet.

Beppe if you are there, where did you get the info that these are transistors?

D. Not sure if this is what you mean but here are the Scalextric instructions for fitting a saloon ship to a dummy Takara module. As you have seen I have not followed it for the LED but have done that the same way as the ready made digital modules to put the LED further foreword.
 

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Although I do not know a thing about electronics,I have found the NASCARs to run well on the 30,000 rpm light blue scalextric motors...........except when using the braking buttons.The lap times increase with the dynamic brake,but the chip will fry very fast.I was going to mail you some chips once before Rich,never did.If you let me know where to mail them,I will send you a dozen or so.I am on vacation this week,so I will be sure to get them to the post office this time. Sounds like your on to a high performance upgrade!

Greg
 

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I fry a SSD chip (25k motor) after a 30 minute session, its ok till you stop, as soon as you stop you have no air flow (cooling), then the mosfet buggers up, the next time you use it , it is on full throttle by itself. Taking off the shell to expose the board, I seen the mosfet glow red and fry after trying again on track (experiment). This upgrade might be the go, I just bought a magnifying glass, mini soldering iron, and a light too, so good timing.
 

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Discussion Starter · #10 ·
OK I stand corrected twas Mauro.


QUOTE (Xlot @ 9 May 2006, 13:38) <{POST_SNAPBACK}>If I understood Mauro correctly (something not to be taken for granted
), the performance of the Slot.it decoder should be - surprise, surprise - noticeably superior to that of the SSD original

This because the output stage uses low resistance MOSFETs instead of transistors, effectively eliminating the good 2 Ohm choke now present

Rich
 

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Hey Rich,
I too am suspisous about the datasheet I found because these devices can only stand a few hundred mils, Not the 2 - 2.5A range you would suspect. I assume that you have mapped out where the pcb traces are going. I was thinking that they really only need a half bridge arrangement to provide forward drive and braking. Do we know what the other components labeled a8e are? Do you know if we are working with a full bridge or just a half bridge? The p03 and n02 components could just be used to provide supply level voltage to the other components (a8e, maybe fet?) gate? If you already mapped the circuit, let me know, otherwise I will give it a closer look.
best regards,
BT
 

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Discussion Starter · #14 ·
Hi BT

I have scribbled out the circuit.

A8E are the driver transistors, one for each mosfet. I am going to assume they are mosfets until proved otherwise because I do not think it would make sense to use anything else.

The N02 device is in series with the motor & driven via an A8E driver with the PWM signal from the processor. The P03 device is across the motor & is driven again via an A8E driver with the brake signal.

All pretty simple, was just curious as to the spec of the original devices, but not important.

Rich
 

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QUOTE (NASCARUSA @ 21 Jul 2006, 10:55) <{POST_SNAPBACK}>Although I do not know a thing about electronics,I have found the NASCARs to run well on the 30,000 rpm light blue scalextric motors...........except when using the braking buttons.The lap times increase with the dynamic brake,but the chip will fry very fast.I was going to mail you some chips once before Rich,never did.If you let me know where to mail them,I will send you a dozen or so.I am on vacation this week,so I will be sure to get them to the post office this time. Sounds like your on to a high performance upgrade!

Greg

Well the chips arrived from Greg this morning. If you think you have problems with fried chips, look at this.




So I thought I would share my findings as I go along.

Have only visually examined the chips at the moment, there are 3 obvious problems.

1) Fried mosfet. Always seems to be the N02 device, not suprising as this is the one that drives the motor. The P03 device is only used for braking.



This is usually visible as a bump on the surface of the chip, although some are more dramatic.

2) Failed Diode. These are the four larger block devices marked FS1A



Here you see a quite dramatic failure.

3) Desoldered Diode. This one was a surprise to me. What has happened here is that the Diode has become sufficiently hot that it has desoldered itself from the board.



This also seems to be the most common failure. Question for Greg, in the pack there were a lot of loose diodes, just want to check that these desoldered themselves, as opposed to you removed them?

So here is the final tally of the 32 failed boards.



Of course this is only a visual inspection, some boards may have multiple faults, it is also likely that a failing mosfet could cause the Diodes to overheat and desolder. Also the the boards without a visible failure will have something wrong with them.

However one thing is obvious. If we are going to get a beefier board, as well as the upgraded mosfet we are going to need uprated diodes and or a higher melting point solder to keep them in place.

Final note on the diodes. They are an FS1A rated at 1 Amp continuous and 30 Amps peak forward surge.
This should be ok for most cars. Greg do you know how many amps your motors take?

I note that the Slot.it board uses a device marked RA 63A but can find no data on this. Can anyone else help?

To be continued....

Rich
 

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Man thats a super-sized bag of chips!

Interestingly I have suffered one instance of all 4 diodes being heated sufficiently to fall off the board. This was in a SCX Maranello, the chip sat just above the conductor rails attached to the chassis floor.

Hell of a job trying to get them back into position, dont have the tools OR the eyesight!
 

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@ drummer ,
oddly enough out of the 100 (I really need to stop counting them ) or so chipped cars I have, the only 2 chip failures were with an SCX marenello ! , third chip has been succesful , no changes made to the installation method either ??
sax
I just mentally added up the cost of all those fried chips............ouch !!!!
 

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QUOTE I just mentally added up the cost of all those fried chips............ouch !!!!

So did I
Ketchup anyone?

That pile is probably worth more than my whole track! Well if they had been working of course!

Rich you have to do something for this man he needs help! Bad!

Or put that box in the "Tate Gallery" and it will probably win an award!

Ian
 

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hmm... and i thought the one in my e-type was bad. i dont suppose its worse if the car just doesn't move? as thats the case. maybe ill send it to you richG if thats okay with a few pennies, so you can fix it?
 

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Hello Fellas,I have been out of town.Those chips are from a year and a half of racing.Most of them were destroyed with the 35,000 rpm,red can motor.When they blew,we just laugh and say Thats racin!Most of the loose chips were the result of crashing when the cars were hot.Most were blown in excess of 15 volts.We now use the 29,000 or 30,000 scalextric light blue motors,at 14 volts,and have little problem,we may still run at 16 volts for a 50 lapper.I have 5 NASCARS with the standard motors,and when run at 14 volts,it all works fine.We have 4 NASCARS with the 29,000 light blue scalextric motors.Two sets of cars for two differant skilled drivers.We are powered with the 10 amp 5 to 20 volt power source.I know those chips lookfunny,but I can say we had a blast finding the limit of the system.We still have a #3 Dale Earnhardt with the 35,000 rpm,always seems good for one race.There are 3 of us that race a couple times a week,2 to 3 hours at a time,usually after work.This is great stress release,and has been well worth the expense.When racing NASCASRS,speed is the ultimate goal.Hope Rich can find us some more speed,cause we have surly found the factory limit.

Greg
 
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