Abrams Tamiya DMD - burned engine power path

[abramsky]

Hello
Today I received a package from my friend with damaged electronics from Tamyia Abrams tank. I opened it and found a burned path in the power cirquit going directly to the MOSFET of the drives. There is a burned path there, but I don't know if there was anything else soldered to it. Something fried there ... but I don't know what. Probably a diode ( reverse supply protection ) or an SMD fuse, or just this path was designed to withstand a certain amount of Amperage calculated by the constructor... but without comparing it with a functional PCB, It's only my guessing.

As I plan to fix this item, I therefore have a huge request to Abrams Tamyia users. Would someone in you be so kind and open your Abramsa to take a photo of this PCB responsible for the drive of motors and LEDs mounted in the loudspeaker?
I mean the other side of it (you only need to unscrew 2 tiny screws in the housing).

I will be very grateful for any help (detailed photos are welcome ).

[abramsky]

Here's a photo of the patient:

[abramsky]

Another part of the investigation. I received information from my friend that the MFU in the tank's turret was also damaged. Inspection also revealed significant havoc in the power path. At least one of the components on the board has fried (I marked the area in red). Probably it was a reverse polarity protection diode ... The temperature was so high that the tin in the vicinity melted ...
I renew my request. If any of you have Abrams Tamyi with original electronics - please provide an exact photo of this area.

[Jarlath]

Overloaded the power circuit? I do note that the power connection is cut off, which normally has the standard Tamiya connector (15A or so rating).
Was it something you did? If not, I wonder if it was subjected to a 3S lipo...

[abramsky]

Thanks Jarlath
I received this electronics from my friend in this condition. The Tamyia connector is of such poor quality that I always remove it immediately after buying new electronics (it was already cut here - my friend already did it) ...
He damaged the electronics because he connected the 2s battery backwards (reverse polarity). The power supply was correct. The place and extent of the damage indicates that the power line had something of a kind of protection against such a situation and exactly those elements that should act as protection in this situation (the weakest links) were damaged. Unfortunately, not having anything to compare with, I can only guess that it could have been a diode (which was supposed to act as a blocking device in the event of connecting the reverse polarity) or a kind of fuse. No photos / schematic - not 100% sure.

[Jofaur86]

Hello

Personally, I would be surprised that Tamiya is planned, a security (fuse or diode) on its electronics? moreover in view of the photos, nothing proves that what is fried, corresponds to any protection? Reverse polarity? generally being what causes the maximum damage, if that part got fried, what should not be better? I do not want to discourage? but, apart from replacing the same electronics or other brand, would certainly be simpler and less expensive (personal opinion and hire than me)

[abramsky]

Hello

Personally, I would be surprised that Tamiya is planned, a security (fuse or diode)

Why not? Is this the standard reverse polarity protection on many power circuits I have come across? Simple and cheap

...on its electronics? moreover in view of the photos, nothing proves that what is fried, corresponds to any protection?

Yep - nothing proves - as i wrote before - only my guessing...

I do not want to discourage? but, apart from replacing the same electronics or other brand, would certainly be simpler and less expensive (personal opinion and hire than me)

I will write this at the beginning of my post to keep it completely clear.
I got this electronics from a friend FOR FREE... I have an electronic education ( almost 30 year ago ) but I have never worked in the electronic professionnaly. But I have been dealing with electronics as a hobby for many years and usual I manage to fix everything I have on my desk. I also build guitar effects for my own use. I do all of this just for fun and to solve problems that most people find overwhelming. It's the same with Tamyia electronics now. It's just another challenge. I do not look at what will be cheaper, because repairing this MFU is only my time and probably a few euro cents for a parts that I will almost certainly find in China (I'm pretty sure that China produces right now everything, even those things that inventors are just starting to dream about them) ...

Anyway, thank you for taking an interest in my case.
Please note this burned path:

This is the positive power line (it goes directly to the MOSFET of the motors). It looks like this path has burned through, but seems that nothing was soldered to it. After opening the (sealed) housing, nothing fell out (if there was any element there would be something left behind). So I think this burned path was so wide and tinned for a one reason. I suspect that it was supposed to withstand as much current as the entire ESC current consumption was calculated - such a simple - disposable fuse. I''m right? I don't know until I find photos of a non damaged module ...

As for the DMD from the tank turret, the fried element might as well just be a high-power resistor. This may be indicated by the size of the element. Unfortunately, without a layout / scheme or a photo of a functional module, it will be more difficult, but because this element is also in the power path - I will just try to draw it and this way I may find a solution;)

Anyway thanks and best regards

[tomhugill]

I have what you need

[abramsky]

After extensive investigation around the DMD MFU (module in the tower) and cleaning the area of the burned element with a tin bubble on the surface, I discovered (using a 12x workshop magnifier) that it was probably a twin MOSFET to the one underneath it, marked 638 ZH (according to the data sheet it should withstand up to 20V 4.5A - but on one condition - that it will not receive reverse polarity ). The layout of the path below it is unclear for now, but after desoldering everything should become clearer. Probably both were soldered in parallel.
Probably most of you do not know what I am talking about, but I know that several people on this forum have electronic education - it will be clear to them

[abramsky]

I have what you need

Great. Do you have the option of taking close-up photos (macro) so that I can read the markings of damaged components? Thank you in advance for your help