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Scalextric Digital Chip Repairs


shadow_rusty

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Just ordered myself a mosfet to repair my dead chip... (Stupidity induced failure... lol)

 

As I couldn't find a ZXMC3A16D on ebay, I ended up ordering a AF4502C as it had slightly better specs than any others I could find that were suitable...

Mosfet%20Comparison.JPG

http://www.users.on.net/~shadow.rusty/Slot%20Cars/Mosfet%20Comparison.xls

 

At this stage, I'm not going to replace the diodes with shotky's, as that gives the chip an unfair advantage... (0.6v extra to the motor)

I will only consider it if I was to upgrade all of my chips, and all of my brothers chips at once as we often race together...

 

A big thanks ti RichG for his outstanding work in providing analysis of these chips...

http://www.slotforum.com/forums/index.php?showtopic=17259&st=0&p=184648&&do=findComment&comment=184648

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Should work Ok, but only trial will show...

 

Bigger drivers do imply an increase in capacitance of the mosfet and so can be a bit slower/laggier to respond - especially when switching from full power to braking, and back. If the two drivers take longer to respond, then you can end up with a dead short across the power rails. That can then cause an overload through them and they can blow. I know that from testing the InCar stuff, where I wasn't delaying enough for the mosfets to decay one driver before turning on the other.

 

Ian

Linux: A '90s reincarnation of a '80s Operating System based on a '70s design philosophy

Website: www.electricimages.co.nz

InCar-PRO: Chip Main Page

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Here's hoping I guess...

At $3 for 2, and the chips already dead, I don't have a lot to lose...

 

Thanks heaps for your input Ian...

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No worries Phil... THanks heaps for the offer... I'll definately keep that in mind...

My biggest issue is going to be removing the old transistors...

Edited by shadow_rusty
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  • 3 months later...

Well, I've fitted it, and so far, so good...

Mind you, I've only run it for 30secs or so, just enough to know it works...

 

The Revision 'G' version chip I have is slightly different arrangement of components to the chips in Rich's link above, but they are the same components.

Also, being a DPR chip, it was VERY hard to fit it in such a way as to still allow it to work as a DPR module...

But it is done, and hopefully I never have to do another one... lol.

 

I will have to build a track on the weekend for some more serious testing...

That's going to be weird... I haven't run digital for ages...

Edited by shadow_rusty
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  • 8 years later...

Bud the last post was 8 years ago.

On chips, we have simply too many to create a video-log. As mentioned earlier in this thread, some were dead-on-arrival, some had no brakes, some had a range with the of about 30cm, some when hooked up to a light kit had only rear lights but not front lights (light kit and LEDs worked perfectly when tested with another chip) and so much more. 
 

 

 

 

www.scorpiuswireless.com

 

 

 

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