# Re-engineering Alltrax



## Tesseract (Sep 27, 2008)

noubal said:


> Any easy method to remove the epoxy in Alltrax AXE4855 ?...


If the conformal coating really is _epoxy_ then there is no way to remove it without destroying the board and components. Same if it is silicone (rubbery, usually white or red). If it is acrylic (usually clear) then practically any solvent - including acetone - will easily strip it. Acrylic is strictly for protecting against high humidity, and some argue it's not even good for that. Polyurethane (usually dark but still translucent) is the most common conformal coating, arguably the most versatile, and the EASIEST way to remove it is with a solvent mixture made especially for that task such as MG Chemicals 8310-100ml ($10US).

In general, one does not boil PC boards in water... if you do so, you will then need to bake at 80-90C (just shy of boiling) for several hours.




noubal said:


> Thinking of re-engineering AXE4855 to AXE144V500A.


Oh boy... not another one... So... what's _your_ plan? 

One thing you should realize is that these low voltage golf cart controllers usually derive their internal power from the traction battery pack. In other words, the throttle pedal, and all other inputs, are not isolated. No big deal when the pack is 36, 48 or even 72V (though that's pushing it in my book) but it's definitely a problem at 144V.

Another thing is that the switches and diodes with a higher voltage rating will necessarily have a lower current rating, and there are only so many holes in the PC board to mount them, so your overall power rating might not change all that much.

But don't let me spoil _all_ of the fun...


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## noubal (Aug 25, 2009)

Thanks for the advice. 
Hopefuly I can find MG Chemicals 8310 here in Malaysia.


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## Jeff (Sep 25, 2008)

noubal said:


> Any easy method to remove the epoxy in Alltrax AXE4855 ?
> Tried with heat gun and scalpel, soak in boiling water and spraying paint/epoxy remover. All seems not working. Next to try is Acetone as recommended in another forum.
> Thinking of re-engineering AXE4855 to AXE144V500A.


Equal parts of Methylene Chloride and Formic acid, applied with a brush will dissolve epoxy. Most commonly used to open semiconductor packages for inspection. It will remove lettering from packages, and attack copper with long term exposure, so handling care and masking must be taken.
We have used this in extreme situations to flip a security bit for device reads.

Often, epoxy potting removal for reverse engineering can be safely accomplished with a hot air stylus (small directed heat source) and orange sticks (wooden picks) as the epoxy softens when heated. It takes skill and patience. This method often yields a working part that can be analyzed.

Jeff


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## noubal (Aug 25, 2009)

Thanks Jeff, your photo is really cool.

How do you reverse the security bit with epoxy remover ?


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## noubal (Aug 25, 2009)

Thanks Jeff.
I had damaged the boards with various chemicals , probably I have to redo the PCB.

BTW: How do you reverse the security bot with epoxy remover ?


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## Tesseract (Sep 27, 2008)

noubal said:


> ...
> How do you reverse the security bit with epoxy remover ?


He's talking about physically removing the epoxy that encapsulates the chip and then zapping the fuse bits to disable them so that he can then read the code that was (formerly) locked inside. In other words, to steal the code.

There are many reasons someone would do this, but I can't think of a single _ethical_ one...


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## noubal (Aug 25, 2009)

Thanks Tesseract,
Bombastic sentence makes me loose sence of understanding.
I have to do the same in my Alltrax project since I had damaged the control board.


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## Jeff (Sep 25, 2008)

Tesseract said:


> He's talking about physically removing the epoxy that encapsulates the chip and then zapping the fuse bits to disable them so that he can then read the code that was (formerly) locked inside. In other words, to steal the code.
> 
> There are many reasons someone would do this, but I can't think of a single _ethical_ one...


(Score: -2, two dimensional thinking)

A fortune 100 company has a technology division with a successful product containing an embedded software program as a key element to it's success.

An ex-employee of this company surfaces strategically with a competing product.

OEM contracts an outside firm to purchase the competing product and subsequently extract software from the product for evaluation. The OEM suspects either source code theft, or program was composed using "unclean hands".
Object code was extracted from the MCU using the materials I described above. I'm not allowed to elaborate further.

Back to EV stuff. Jeff


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