I am attempting to convert a project over to using a Teensy.  I uploaded

I am attempting to convert a project over to using a Teensy. I uploaded and changed the program to run appropriately with the faster clock. The teensy works fine when load a sketch with the USB plugged in but if I unplug the USB and power everything down and then back up. I get nothing from the Teensy. Hard to debug what might be going on since I see nothing and it always works with the USB plugged in. Any ideas? Anyone else seen this?

What happens if you power the teensy via usb (but not necessarily have it plugged into a computer, e.g. a usb phone charger)

Same thing. Nothing. I did cut through the USB/VIN padds because I provide external power.

Ah - what does your setup function look like? (I generally strongly advise against calling show in setup because i’ve seen it mess with the comeup of the arduino library. Also, for laughs, try tossing a small delay in your setup function)

The GND on Teensy only connect with USB GND and not connect to power supply and LEDs GND???

I found a delay(2000); in the start of the setup does wonders for some reason.

I put a 2 second delay at the beginning of the setup and 2 second at the end. Seems to do the trick. Not too worried about 4 seconds in the scheme of it all… Hmmm.

Thank you for all your help!

Same here. I now put a 1.5 sec. delay first thing in setup() for Teensy. My sketches would hang even if connected to USB unless I opened the serial monitor. Had me stumped for a while…