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Robox mainboard IC identification help

New Member Customer

Not sure if any one will be able to help and not really expecting much but it's worth a shot.

Have an old robox RBX01 that not working -  for disclosure it came to me in a non working condition with no history or info.

On the main board there is a chip marked:

027 45UCG in position U5 on the board has anyone any idea what this is? there seems to be 4 in total all the same. U5, U8 ,U11 , U14

<img src=" removed link " />

Just trying to get a handle on the layout , components etc as there seems to be an issue with some signals at the head.

Namely the ic2 clock line does not seem to be working while it's signal is visible and recognisable on a cheap scope its peak to peak is only a couple of millivolts around 3.3v and so does not go low enough for the eeprom to recognise as being low. (The pin also seems to share continuity with the 3.3v power line which I am pretty sure is wrong)

The ic2 data line however does appears correctly on the scope

Not sure if there is a publicly available schematic or if someone knows what that chip is.

p.s sorry for edits image of chip keeps getting removed 


Topic starter Posted : 11th April 2021 2:18 pm
Former USA Robox Support Moderator

@tundras What you are describing seems to be the power MOSFET for the head. The head power cable has likely been installed backward and this MOSFET has been blown. It is not repairable in my experience because the reverse connection damages the traces on the mainboard. 

I suggest purchasing a new mainboard with the upgraded drivers as it will be more cost effective than attempting to repair this damaged mainboard.

Posted : 14th April 2021 3:22 am
New Member Customer


Hi pretty sure it is not a mosfet would not make sense with the pin arrangement that I have been able to deduce- (I know there is a power mosfet in the head itself which I guess would take the pwm signals for fan and hot end) I have not done much further investigation on that ic but I am presuming it is something to do with either filtering or protection. 


The issue however is not that IC? I did remove it and the clock line still shows continuity with 3.3v power rail - I the removed the main mcu "ATSAM3U2E"  and the continuity disappeared. So it seems likely the internal transistor that pulls down on the port in the mcu was fried(Hence I could see the correct signal on the scope but only with like 20mv peak to peak so when the mcu was attempting to pull it low it ended up floating high).

I may replace the MCU (just as a personal exercise) or perhaps get a new board or just strip the machine for spares I have not decided yet. 

Thanks for your reply but if anyone does know what that ic at u5 is doing I would be interested.


Topic starter Posted : 14th April 2021 8:37 am
Prominent Member

@tundras Marcin aka would almost certainly know, as he has swapped the MCU out on a few damaged logic boards in his time, although he has not been active for quite some time now.



Posted : 18th April 2021 11:41 pm

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