Microdot digits 1&2 usually dead

Hi,
I have several microdot hats. One, that I soldered up today from a kit, has digits #1 & 2 dead. Actually those digits come up for a second and then go off, and I start getting “IO Error” in my python terminal output. Other microdot hats work fine. I don’t think I fried the controller chip for those digits (I’ve been soldering since circa 1978 and have reasonably good ESD-safe technique).
Any thoughts?
I’m just getting into the libraries for the microdot hats, and haven’t done a full code review, so let me ask, are there any diagnostic commands to probe the controller chips?
Thanks,
John
SF, CA, USA

It’s using i2c so you could run sudo i2cdetect -y 1
You should get back 0x61, 0x62 and 0x63

  • 0x62: IS31FL3730
  • 0x63: IS31FL3730
  • 0x61: IS31FL3730
    It sounds like one of the 3 IS31FL3730 LED matrix driver chips is having an i2c issue. If I have it right each chip drives two digits / displays.