My Beagleboard is kaput

After a year of faultless use I seem to have killed my BB -xM while disconnecting the power supply. Now when I connect, the red over-voltage LED lights and that’s it.

I tried powering through the OTG. That gave me both red & green power LEDs & the board booted as far as the RISC OS prompt complaining that there was no keyboard & that it was waiting for the boot drive. I presume the USB ports aren’t functional powered this way – the USB power LED flickers.

I’ve tried another power supply with the same red LED only as result. Both supplies meter at 5.3v.

I’m guessing (I’m not otherwise qualified!) that the power management’s been fried.

Is my supposition likely to be correct? If I’m forced to buy another BB -xM is there a power supply available that’s less likely to cause damage than the Maplin L11BQ I’ve been using?

Is it a regulated 5V supply? 5.3V seems a bit high…

Is it a regulated 5V supply? 5.3V seems a bit high…

I thought it was regulated but now can’t find any mention. It’s a switched mode model, switchable voltage at 4A.

I see in the BB -xM manual that the specified max is 5.2V. Perhaps I’ve been running a year on luck. Over voltage protection?? In normal usage the red LED didn’t light.

When loaded the voltage will likely be around 5V but on switch on and switch off an unregulated power supply will be higher….

I measured the voltage when disconnected.

I guess it’s buy a new BB time?

From what I can remember, the USB OTG port doesn’t supply enough power for the USB ports, hence no boot drive or keyboard/mouse. I have had the red overvoltage LED lit with the power plug only partially in the socket (leakage?). Maybe one of the power port connections on the board were dry joints and unplugging the plug finally ‘broke’ the joint. If you’re not confident to do so, get someone to go over the soldered connections with a soldering iron (on the power port socket).

Maybe one of the power port connections on the board were dry joints and unplugging the plug finally ‘broke’ the joint. If you’re not confident to do so, get someone to go over the soldered connections with a soldering iron (on the power port socket).

They look good to the eye but that’s worth a try. I can manage an iron ok, though my experience is with strip board so might not be confident with anything too fine. Should I earth anything apart from me?

If the soldering iron is a mains one (not electronically controllable, low voltage) you should be ok. Low voltage ones (controllable etc.) usually have an earthing point that you ‘touch’ the tip to. Another thing to try before the soldering iron (the power plug joints are quite large) is to see if you’re getting 5V on the socket as it could also be broken internally.

Thanks for that. I’ll give it a try tomorrow (don’t think I’ll have a steady hand today – house buying stress).

Should I earth anything apart from me?

Actually the main thing is not whether you, the iron or the work object are earthed, but that you, the iron and the work object are ALL at the same potential.
A connection the links the irons “earth” to you AND to the board will eliminate the difference voltage.

NB. with all those linked you could “float” the whole setup by not connecting the linked set to a normal earth.
This kind of thing has been done with isolated front ends for medical kit for decades where there is NO earth route from the patient contact front end and the powered circuits in the main body of the kit. The mini-isolation devices (transformers) have isolation in the kV level.

I’ll, ahem, take your word for that! I was just noting the warnings of the BB’s sensitivity. It was easier in the 1970s when I dabbled with kinetics.

I hope I understand right and I hope I find the right words without misunderstandings.
The BB isn’t sensitiv. As I work in 2010 on the ARMini prototype I take the 12V Powersupply in the xM and the red over-voltage LED lights. The ARMini Powersupply has the same plug (5,5/2,1). Disconnect and take 5V … no Problems. If you read the Reference
Manual you find “max. Power without damage is 12V”. The Over Voltage LED, D13, turns on whenever the DC voltage exceeds 5.3V. The ARMini internal power is 5,3V without connecting the hardware. With connecting there is 5,2-5,1V.
May be the Ampere peak is problematic when you hot-remove the plug.
You can use the “Board Verification Test Points” to control the voltage. If you have, take a USBtoPower-Adaptercable (Any external Devices use this) and take the power from a HUB or Laptop-USB. This voltage should be within specification.

The BB isn’t sensitiv.

I meant sensitive to static whilst I’m handling it to solder.

You can use the “Board Verification Test Points” to control the voltage. If you have, take a USBtoPower-Adaptercable (Any external Devices use this) and take the power from a HUB or Laptop-USB. This voltage should be within specification.

Some more for me to try, thanks.

For future reference, is this the sort of thing I should look at;

Regulated power supply?

I have soldering any things (e.g. resistor out, rtc-battery in on the xM, LCD port in on the normal BB). No problems. I use a basic soldering station.
This regulated power supply I have. It works ok.

The BB is out of its case & I’ve done some initial checks. The 5V socket shows continuity & doesn’t short. Rather than attack immediately with the soldering iron I took a reading between the +ve pin at the back of the socket & the ground pin by the camera connector, P10. It was 5.3V. A continuity check between the 5V socket +ve centre pin and the +ve pin at U32 was good as was a check between socket -ve and OTG -ve. Am I correct in assuming a good connection twixt socket & board and negates the need to solder?

I took a reading off J2. It’s at 0. I’m assuming there’s life elsewhere given that RISC OS tried to boot (snail’s pace) when powered from the OTG.

Red LED D13 is bright rather than dim as it is when the board loses power or the plug partially inserted. USB LED D14 is lit & steady. None of the others light.

I haven’t had the opportunity to try Raik’s last idea, not having a suitable cable.

Have you tried a serial connection to a PC to see if it is getting as far as starting the bootloader?
I don’t remember if it is a straight of crossover lead, but since we only want to look for info, two pieces of wire would suffice (GND to GND, then either TX or RX into PC’s RX). 115000, 8N1.

Have you tried a serial connection to a PC to see if it is getting as far as starting the bootloader?

Unfortunately that’s another piece of equipment I don’t have (PC), only a Mac. Only thing I have here with a serial port is a RPC. The power LED doesn’t light when powered from the 5V socket – would anything else start?

I wouldn’t know what to do anyway. To give context, my discipline is fine arts (ducks). I used to use electronics a little way back when for art projects but always had to have someone else do the circuit designs & testing. I did the soldering/construction. So don’t expect expertise :-<

If I right understand, the Board boot RISC OS when it is powered by the OTG and not when it is powered by the 5V socked. Have you take a look in the schematics? If I have a little time I will do this in the evening. Tests on my board I can do monday morning :-(

If I right understand, the Board boot RISC OS when it is powered by the OTG and not when it is powered by the 5V socked.

That’s correct. It boots with the OTG but more slowly than usual. Also both LEDs 12 & 13 are lit & the USB LED 14 brightens & dims alternating (there’s a word for that but not during a senior moment). I think the linux card that came with the BB boots that way too but the screen mode it starts in isn’t compatible with the monitor I have so I’m just going by the LED flickers.

If I have a little time I will do this in the evening. Tests on my board I can do monday morning :-(

That’s kind of you. I’m hoping to exchange deposits on a new house in the next couple of days so might not be too engaged with the BB.

Could get a USB to serial adapter for the Mac. Or, the test that Rick wants you to do could be done on a RiscPC, too – really, anything with a serial port.

Rummaging through my bits & bobs I’ve come across a 25/9 pin modem lead, a 25 pin gender changer, a 25/9 pin D plug adapter and a 25/9 pin null modem I made in another life. Perhaps I could do something with those? But what?

Sorry, I think I’m being clueless.

Right… Looking a bit deeper, it seems as if this may be an ‘issue’ with “U19”. This is just above the OTG port to the right, if you hold the board with the OTG pointing down. Somebody else’s image here: http://i.imgur.com/g8ZUN.jpg Check the soldering on/around this chip.

If that doesn’t work, get in touch with the Beagle site to request an RMA. If you are not getting as far as the board even attempting to power up, then something is wrong…

Mmm… <thinks> if there’s an overvoltage protection circuit, surely the USB should not be powering up (as indicated by the USB LED)? If the overvoltage LED is on, this should imply the protection circuit is active, which by definition ought to imply that there should be no power on the 5V and 3V3 rails?

Your 12V supply, it wasn’t a centre-negative supply, was it? The Beagle needs centre +ve (or “center hot” in American parlance).

Also… You wanna be real careful what you use as a power supply.

http://hackaday.com/2012/01/06/running-the-numbers-on-a-cheap-psu/

http://www.youtube.com/watch?v=DZDh8z9UDTo

http://www.blue-room.org.uk/index.php?showtopic=49672

https://picasaweb.google.com/115846007645315423701/FAULTYPSU?authuser=0&feat=directlink

Right… Looking a bit deeper, it seems as if this may be an ‘issue’ with “U19”. This is just above the OTG port to the right, if you hold the board with the OTG pointing down.

Not on a rev C board. Not there anyway. Just an empty space.

If that doesn’t work, get in touch with the Beagle site to request an RMA.

A possibility once I know where my abode is.

Your 12V supply, it wasn’t a centre-negative supply, was it?

It’s reversible and set to centre hot and has been for the last year. It’s switched as a 5V supply.

Also… You wanna be real careful what you use as a power supply.

That’ll be my first port of call once I’m settled. Seems finding a trustworthy supply is more of a challenge than it should be.

Thanks.

Seems finding a trustworthy supply is more of a challenge than it should be.

;-) I think the basic premise is “if it costs less than a pint, run like hell in the other direction”.

Now I don’t drink so I don’t know the price of a pint, but I figure something that will be posted from Hong Kong and cost a fiver all in is not something I want connected to a device that I value.

There is, perhaps, a place for boot sales and power supplies from ‘80s/’90s equipment. As I mentioned a while back, my Beagle is running off an iomega Zip power brick. I know it is very stable as some experiments elsewhere showed me that the rotational speed of a zip drive (100mb one) seems to vary depending on voltage (which is horrific – there’s no vreg? it isn’t a sync’d stepper?) so I at least know that when the supply says 5V, it’ll be dead on 5V.
Likewise, an ’80s computer supply that is a 5V brick should do the trick. If not, it might be possible to replace the voltage regulator to make it 5V. This would probably be okay in a 6V brick, maybe less so in a 12V one.

At any rate, yes, beware cheap power supplies.