The display generates high-voltage to function. Initially a 20V transistor was chosen according to measurement that had been done previously, but assembly of more units showed several reliability problems that were fixed by switching to a 25V transistor.
More investigation/probing should be done to ensure that the transistor rating is respected at all times. The e-ink display datasheet does not clearly mention how high the voltage can be. A new transistor should be specified in the BOM.
The display generates high-voltage to function. Initially a 20V transistor was chosen according to measurement that had been done previously, but assembly of more units showed several reliability problems that were fixed by switching to a 25V transistor.
More investigation/probing should be done to ensure that the transistor rating is respected at all times. The e-ink display datasheet does not clearly mention how high the voltage can be. A new transistor should be specified in the BOM.