My BBB with a F8-B cape will not start on power up

[Sawdust]

My BBB with a F8-B cape will not start on power up, well with a 300W 5V Power Supply.  Seems to do fine on 100W, 80W and 10W PS, but not the 300W.

Any suggestions?

I use Wifi on/off timmers to  power down all my PS when not in use.  This is working for all other BBB, PB, and Pi's, except the BBB with the 300W unit.  (I've tried other BBB's and Capes-no change)  This board is the one inaccessible, so pushing any button just won't fit the plan.  It will power on if I power off and back on...some tings two or three times to get it started.
My only thought now is to add an small 5V PS just to power the BBB....Space is an issue, but with a big enough hammer, I can make it fit.

[dkulp]

The beagles have a fairly specific timing requirement on power on.   If the power supply cannot jump from 0V to 5V within the time limit it needs, it won't power on.   It sounds like the power supply you are using is too slow.    This is only a real problem with the 5V power supplies.  Those of us that use 12V would be impacted less as the power supply would just need to get to about 7.5V before the buck can start providing the power that is needed.    

I would try a different power supply if you can.   Ironically, in general, the "cheaper" supplies are better.   One of the expensive MeanWell's are known to take WAY too long to get to 5V.  Cannot remember which model.

[Sawdust]

Thanks Dan, that seems to be the problem.

Hmmm...PS appear to be pretty zippy O to 5V. Tried the spare but same intermittent starting. Pulled the cape jumper and added a dedicated 5v5A PS just for the BBB.  Getting 100% start.

I have ordered a 5V "time delay on" relay to replace the second PS.  TDOE seems to be the best solution.

[nmiller0113]

Thanks Dan, that seems to be the problem.

Hmmm...PS appear to be pretty zippy O to 5V. Tried the spare but same intermittent starting. Pulled the cape jumper and added a dedicated 5v5A PS just for the BBB.  Getting 100% start.

I have ordered a 5V "time delay on" relay to replace the second PS.  TDOE seems to be the best solution.

I'm experiencing the same issue.  I've been using a 5V PS connected to the Barrel Connector on the Beaglebone though, with the cape jumper pulled.  If I add the cape jumper back and am using my 12v PS to power the board and cape it works every time I've tried.  You seem to have switched to doing it the way I am with a dedicated PS and are getting 100% start.  May I ask which power supply you are using...also...I'm not sure what you're referring to in the time delay and why that helps.  Thanks!

[AAH]

I had the BBB starting issue years ago. I fixed mine at the time by installing a switch inline with the power supply to the BBB. I'd power the power supply up and then flick the switch on.
If you were looking at a less hands on option then connecting a 5V relay inline with the power would give you an instant 0V to 5V transition. The 5V from the power supply would go direct to the coil with the 5V also going to the common of the relay. the NO contact would feed the 5V to the BBB.

[Sawdust]

My 5V5A PS was just a China white box unit I used on the workbench. Not a wall wart.

Time delay "ON" relay: Dan feels the intermittent starting of BBB is due to voltage not ramping up fast enough to trigger the BBB to start. Well, if I place a TDOE relay in line with barrel connection and the jumper bulled, I can keep the BBB from seeing the power until it is at full voltage, then the relay clicks in.  0-5V is instant.  I'll likely set it for 5 seconds delay.

https://www.aliexpress.com/item/32866909967.html?spm=a2g0s.9042311.0.0.d97f4c4dH1btJJ
You cannot view this attachment.

AAH: The switch is good, but I'm 15 feet in the air and wanting automatic operation. TDOE Relay seems to be the best solution.

[nmiller0113]

That makes perfect sense.  Thanks for sharing and to both of your for your input!

[Sawdust]

Received the 5V TDOE Relay today - installed and tested.  About 1 sec delay and the BBB starts every time.  This little relay is much better that a second BBB only PS.

This is the relay I bought . . I had these in 12V and they work great.  Not many operations, but 2 or 3 years in service. With the experience with these in 12V, I did them for this 5V application.
https://www.aliexpress.com/item/32801536315.html?spm=a2g0s.9042311.0.0.37094c4d07Xl82