# Help - Avid Smart VFD 4H spindle not running! **URL:** \ **Category:** General Chat\ **Created:** [July 4, 2026, 10:46pm UTC](https://forum.avidcnc.com/t/help-avid-smart-vfd-4h-spindle-not-running/6327 "2026-07-04T22:46:07Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Adam](https://avatars.discourse-cdn.com/v4/letter/a/4af34b/32.png) [@Adam](https://forum.avidcnc.com/u/Adam)\ **Post date:** [July 4, 2026, 10:46pm UTC](https://forum.avidcnc.com/t/help-avid-smart-vfd-4h-spindle-not-running/6327/1 "2026-07-04T22:46:07Z")
Family/ Avid Team, I need an urgent help diagnosing and resolving a current issue with my CNC , it’s been 2 days now and I paused all my work and projects ,please let me know if someone can help walking me through resolving this issue or any suggested work around… i have a CNC pro 6x10’ servo with ex controller and smart VFD 4H My Avid CNC (running CNC12) stopped the spindle **in the middle of a job** while the machine continued jogging normally. Since then, the spindle will not start from CNC12. Here’s what I’ve verified: - I can hear a click coming from the Ex controller box after sending the command to run the spindle but the spindle doesn’t run. - The spindle runs normally when started directly from the Mitsubishi FR-D720 VFD in **PU mode**. - The VFD has no fault codes and works correctly. - The VFD is in **EXT mode** during CNC operation. - M3 S18000 in MDI does not start the spindle. - The VFD receives approximately **5 V** on terminals **2 and 5** (analog speed signal). - The VFD **RUN LED never turns on** I checked the wires and I didn’t see lose wires anywhere… could this be a relay ??? Can someone help please? Thanks, Adam ---
**Author:** ![PaulC](https://avatars.discourse-cdn.com/v4/letter/p/e9a140/32.png) [@PaulC](https://forum.avidcnc.com/u/PaulC)\ **Post date:** [July 5, 2026, 12:48am UTC](https://forum.avidcnc.com/t/help-avid-smart-vfd-4h-spindle-not-running/6327/2 "2026-07-05T00:48:55Z")
I don’t have that VFD but there is likely a way to configure the VFD so that it starts the spindle without any connection to the AVID control box. I would start with that to shrink the problem space. If you can start it manually you have a crude solution that will let you get some work done. If you are seeing 5v at the VFD it is likely the VFD though there is a direction signal in there as well. I would have thought 18000 rpm would be higher than 5V. If the VFD can control the spindle “manually” the I would reseat the spindle wires. Then I would just wiggle them around to see if anything changes. Good luck. ---
**Author:** ![jjneeb](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/jjneeb/32/244_2.png) [@jjneeb](https://forum.avidcnc.com/u/jjneeb)\ **Post date:** [July 5, 2026, 9:05pm UTC](https://forum.avidcnc.com/t/help-avid-smart-vfd-4h-spindle-not-running/6327/3 "2026-07-05T21:05:41Z")
I had a similar problem a couple weeks ago on mine. Turned out to be a bad contactor for the spindle enable. Since i don’t have plasma, i could just move it over to the plasma head enable channel on the contactor. ---
**Author:** ![Eric](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/eric/32/3220_2.png) [@Eric](https://forum.avidcnc.com/u/Eric)\ **Post date:** [July 6, 2026, 2:27pm UTC](https://forum.avidcnc.com/t/help-avid-smart-vfd-4h-spindle-not-running/6327/4 "2026-07-06T14:27:59Z")
Hey @Adam I’m wondering if your contactor might have died. Thankfully you may be able to fix it with some small flathead screwdriver: > **[New video · Monday, Jul 6 🎬](https://photos.google.com/share/AF1QipNpe0vpQrbCnVUMjtcXe72tiv7dTYlI9lCbtT0fTC3XctpEI46-T5I8BjkNjPXIGQ?key=Rl9wZFp2cUVPNUhYYVB6a1J3LXgtVG10a3lnRlNB)** Give this a shot and see if it works for you. Check for loose screws first. If that doesn’t work do the wire switching that I show there. If THAT doesn’t work make a support ticket using the link up top and they’ll get you squared away.