EB006 v9 possible short circuit

[WvdBerg]

Hi,

Seems like i have a short on my EB006 v9.
Normal operating current for the board, seems to be round +/- 100mA with no external loads connected.

All off a sudden its running in excess of 1A indicating a short circuit somewhere. First though it might be the U5 ( L7805 ) reg acting up but isolated the regulator by powering from USB but no change, 3.3V rail also collapses.
So something else then the on-board power supply is pulling the board down.

U2 (PIC24EP512) heats up instantly so makes me want to start there first. Which already poses a problem.
Can upload thermal images if that will help the faultfinding process or do i have to send the board back to get sorted out ?

The strange bit is i can't figure out what happened?? All was working as normal, got the compiler message attached and went into a short straight after that.
Using a bench switch mode PSU set at 15.5Vdc, it hasn't given me any indication that in the last 5years that I've been using it, that it might be problematic so i don't believe the problem originated from there.

Before i take a harder look at the short, though I'd first hear what the matrix hardware guys can tell me.

As you can see code protect was disabled so i don't know where the warning comes from?

[medelec35]

Hi WvdBerg,

Using a bench switch mode PSU set at 15.5Vdc

EB006 V9 Datasheet on pages 5 & 6 states that 7V to 9V external power supply should be used.
from EB006 V8 the circuitry has changed so chips cam be programmed by using power from just USB if required.
So a charge pump circuit was added to raise VPP to required voltage.
Since all the extra added features, more power is being drawn from 5 volt regulator when plugged in to an external supply, the 5V regulator will probabbly get too hot with 15.5V and become damaged?

As for the programming side, Have you tried programming via 2second mLoader ?
If not, you can download it, extract to a new file, then set up compile options to use the new version.

If that does not work, then I have got a 16F1937 on my programmer.
If you would like to post the file that gives the warning, then I can see if I get the same results.

Martin

[WvdBerg]

Hi medelec,

Thanks for the response

Looking at the circuit diagram of the EB006 i don't see how running at a higher DC(in) would negatively effect the operation of the board. Yes you will have higher loses over the device but under normal conditions you should never exceed 1W of power dissipation which the L7805 D2Pak can handle comfortably ( and this obviously only applies to the specific parameters I'm running on at the moment ) . And like i mentioned earlier the normal operating current that i observed was round 100mA, if the output current of the reg would increase so would the supply current, being linear and all...

Lets say the regulator was being pushed into the red you will notice discoloration on the device long before it fails. And that would also be a long term effect not instant.

In this instance that ain't the case, as i monitor supply current out of habit and noticed after programming the chip that the supply current increased dramatically. Naturally had a look at the on board PSU first. Both the 5V rail and 3.3V rail was being pulled down so that tells me that is not a PSU problem but something else. That in conjugation with the bootloader PIC heating up almost instantly i can only be lead to believe that something went wrong during the programming cycle and pushed the bootloader into an over limit condition and shorted it out somehow. No way apart from replacing the bootloader and recoding the 16F processor would i be able to proof otherwise and try to figure out what went wrong.

I imagine i can buy the bootloader pre-loaded and just reseat it on my side?

On the programming side, won't be able to test the 2second mLoader untill i have a fully functioning programmer again, ones that's back up and running i'll look into that.

Can PM you my flowcode if you want to have a look but i don't see how that would help. As it compiled without any problem multiple times before.

[Benj]

Hello,

I will PM you a returns form so you can return the board for a replacement as it sounds like the board has been damaged by something. Do you have any additional circuitry connected to the board which might be trying to consume so much current or may explain what cause the board to become damaged.

[WvdBerg]

Hi,

No been using the standard E-Blocks with the programmer, can in the meantime confirm that the bootloader was the source of the short.
Got one of my guys at the office to remove the bootloader and the board is back to normal operating current. Couple of barrier diodes faulty but they are easily replaceable.
Now i don't know how this effects warranty on the board. Will discuss in PM.

Also lost the LCD e-block in the motion, out of experience you only lose an LCD if you exceed its VCC-VSS threshold with is normally 5.5V with respect to VSS, not sure about the model on the LCD e-block though.