01-23-2021, 07:54 PM
(01-23-2021, 06:10 PM)Aergan Wrote: Hi, I received my PINECIL (2nd run) recently and used it twice over a 24hr period. This evening I found it would not turn on at all and sure enough, same issue: RT7272B is shorted.
Removed the RT7272B, but no luck, it's not powering up nor detected as a device following the steps to enter DFU mode for firmware update. Looking at the layout, I would not think the RT7272B being absent would prevent it turning on if the rest of the device was in a healthy state, so I assume some significant damage has occurred elsewhere.
As far as I see, the input of RT7272B called VBUS_TYPEC which is also the same line which is available at DC input connector.
This RT7272B has an output of VCC_5V which is set to 4.2V as the comment says.
Then LP3986-33 has VCC_5V as input and VCC_3V3 is its output.
Furthermore, the microcontroller is powered from this VCC_3V3 line.
So, if the RT272B is not soldered, there should be no VCC_5V line, so there should be no VCC_3V3 line, so there should not be any action by the microcontroller as it is not powered.
To power it on, you should have some replacement power supply to power the 5V line so to have some chance to power it on at all.
However, I would check if there is no short-circuit on 5V line and 3.3V line prior powering on and also a current limited power supply would be good for troubleshooting.
It is also considerable to apply 4.2V instead of 5V because they may have reason of powering at 4.2V.
(One reason is the power loss at 3.3V LDO but other components may also have lower rating.)
