Author Topic: ATXRaspi R2.6 shuts off during or after booting [solved: bad stepDown regulator]  (Read 457 times)

stevePi

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My ATXRasPi has just started doing the same thing. I built an AllStar node a month or so ago (Pi 3B, UHF radio, and ATXRasPi) and it's been working fine until recently. Powering on/off exactly as expected.

Now it behaves as described above - it powers on for a few seconds, starts to boot the Pi, then it shuts off the power. It does, very occasionally, complete a boot successfully.

I've tried the pull-up / pull-down resistors as suggested above, but in my case that didn't seem to help (assuming I interpreted the instructions correctly).

I don't think it's a lack of power, as the input is 40A 13.8V --> 5.25V 3A DC-DC buck --> ATXRasPi (measured as 5.26V input, and 5.22V output to the Pi). Voltage stays around 5V during the (very brief) boot sequence. I've used good quality wire for the DC connections too.

Any suggestions?
« Last Edit: August 05, 2021, 10:26:33 AM by Felix »

Felix

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #1 on: July 31, 2021, 09:45:04 PM »
stevePi, I see you have an older version, which one exactly is that?

stevePi

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #2 on: August 02, 2021, 10:57:22 AM »
Hi Felix,

It's a version 2.6 board. Been sitting on the shelf a while :)

I've tried disconnecting the USB audio fob and Oled screen from the Pi3, so the only connections are to the ATXRasPi, but the problem remains. I've even tried a different Pi3 and it's the same - starts the boot for few seconds then it shuts off the power. I thought it might be dodgy power connections, so I've soldered the 5V and Gnd to the ATXRasPi instead of using Dupont connectors, and still the same problem.

I've added the pull up/down resistors (see photo) but that's made no difference either. Wondering if I've done that correctly?

It's frustrating as it had been working fine, but now only boots successfully very occasionally, and sometimes still cuts the power randomly even then.

I'm starting to think I've somehow damaged the ATXRasPi? Any other suggestions?

Felix

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #3 on: August 02, 2021, 11:04:01 AM »
The pulldown should be on the SHUTDOWN signal.
I cannot speak to the state of your board without inspecting it.
Have you upgraded that Pi lately? Can it be possible the Pi asserts the GPIO randomly during boot?
To really know what's happening you'd need to use a DMM or scope to look at the signals, clectronics is no guess work like software.

stevePi

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #4 on: August 02, 2021, 11:32:05 AM »
OK, now I'm a bit confused. Earlier you advised smoove that:

"Can you pull-DOWN the left most pin "SoftBTN" (which you have untouched)?
Can you pull-UP (to 5V input) the second pin which is next to it (this is one of the "POWER BTN" pins that is not grounded)."

Which is (I think) what I've done? Gnd via 1.2k resistor to the SoftBTN, and +5v via 1.2k resistor to the power button pin beside it.

I don't think anything's changed on the Pi recently, and I've tried two Pis just in case.

Felix

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #5 on: August 02, 2021, 02:04:50 PM »
No, because you have an OLD 2.6 which does not have any of the jumper options of the R3.
Something else is going on with your board.
At the very most you should keep the SoftBTN pulldown and maybe add one to the SHUTDOWN like I mentioned. I split this into another thread. (Please note the "R3" in the title and body of the other thread).
« Last Edit: August 02, 2021, 02:06:24 PM by Felix »

stevePi

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #6 on: August 04, 2021, 07:28:19 PM »
Hi Felix,

I changed the pull-down as described but no change. It's frustrating that it does sometimes boot successfully, but with no apparent change that I can detect.

I'd like to buy 2-3 more of the v3 boards (assuming mine is damaged), but the postage to Australia is pretty serious. Are there any other options that DHL Express? That's almost US$50 just for postage!

Thanks,
Steven P.

stevePi

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #7 on: August 04, 2021, 11:11:01 PM »
Ah, I may have found the problem!

I noticed another discussion about problems with a cheap switching power supply. So I connected a *different* cheap PS, and it booted fine.

I'll get a scope onto it later, but what do you think? Maybe too much DC ripple on the first cheap DC supply?

I had been using the ubiquitous D-Sun mini 3A DC step down power supply. See photo.

Regards,
Steven P.

stevePi

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #8 on: August 05, 2021, 07:44:30 AM »
Sure enough, that was it.

I put a "big" capacitor across the output of the DC supply and it's now working perfectly.

Still doesn't explain why it worked for a month before deciding to be cranky about the power supply, but it's fixed now anyway.

Thanks again,
Steven P.

Felix

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Re: ATXRaspi R2.6 shuts off during or after booting
« Reply #9 on: August 05, 2021, 10:25:18 AM »
Good to hear, thanks for the follow up. Marked as [solved]