China tach doesnt work

67Dart273 said
Might be this

https://datasheetspdf.com/pdf-file/594110/MCC/2SC1623-L6/1
That center terminal is the collector

Info on the larger chip, HT1621B

https://datasheet.lcsc.com/lcsc/2108251130_HTCSEMI-HT1621BRQZ_C2886391.pdf
I am unable to read the smaller chip

yes the big chip is only the LCD driver. That little L6 is a 400-600 gain NPN. I can inject a square wave into the Base and pick up a reading.