# ESC rail power issue

Source: https://forum.modalai.com/topic/797/esc-rail-power-issue
Category: ESCs, Sensors and Accessories (https://forum.modalai.com/category/15/escs-sensors-and-accessories)
Tags: esc
Posted: 2022-03-10 23:52:19 UTC by Jimk_Aero
Replies: 1 · Views: 999

## Jimk_Aero · 2022-03-10 23:52:19 UTC

Hello again.  In my previous post I spoke about not being able to calibrate ESC's in order to run all 4 motors on my quad.  At that time, 3 motors ran and 1 motor did not.  I finally concluded that I had either a motor or ESC problem, so ended up getting 4 new motors and 4 Castle ESC's.  Now only 1 motor will run.  That one motor has an ESC with a BEC to power the PWM rail as is the norm in most quad builds.  Am I correct in assuming that the PWM +'s and grounds are all connected together so that one BEC should power all the ESC's?  With that one ESC hooked up I do not see power on the other pins, which is confusing.  Can you help?

## Reply by Jeremy Schmidt (ModalAI staff) · 2022-03-11 00:55:23 UTC

Our PWM breakout board does not have the positive rail connected.