Test Jig for the HV Rescue Shield

HV Rescue Shield Test Jig

This weekend I threw together a simple test jig for the HV Rescue Shield.

The completed jig is shown above.  There are four header pins, one at each corner, that are used to align the  BUT, or board under test.  The Kapton tape insulates the two bottom standoffs from shorting against the bottom of the BUT.

Pogo pins are used to make electrical connection to the BUT.  I connect to +5V, ground, 12V_EN, and 12V_SW (the +12V output).

These pogo pins are similar to the ones Ladyada uses in her test jig tutorial.  You can get these in a wide variety of styles on eBay. I think the ones I used are P75-K “chisel” type tips.  They just happen to fit into the existing holes in the PCB with no modification.

The height can be adjusted by melting the solder around the pogo pin and pushing it up and down.  I lost a couple pins when I pushed them down too far and let solder get into the spring mechanism.  Oops.

HV Rescue Shield Test Jig

The standoffs are made of reclaimed screws that I had lying around.  Right now I am connecting to the pogo pins with clip leads, but I might make a more permanent test setup someday.

HV Rescue Shield Test Jig

To test a board, I align it with the header pins and push down.  Easy.

Previously I was using something similar, but without alignment pins or standoffs, so it was challenging to align and push down the board-under-test with the pogo pins without the whole setup sliding around the bench.  The new jig works well and makes testing a large batch of boards a breeze.


Here’s my current testing setup.

Testing the HV Rescue Shield

The output of the 5 to 12V DC-DC converter is shown on the top display (that’s my beloved Fluke 45 bench meter) while the power supply current is shown on the bottom.  The toggle switch on the bench just to the right of the jig is so I can toggle the 12V_EN line and make sure the DC-DC converter turns off too.

This board looks good, and so did 29 of his friends.  0% failure rate on this build!  I seem to have my process pretty much figured out now.

Tested boards

2 thoughts on “Test Jig for the HV Rescue Shield”

  1. $20 for a board to rescue a chip thats worth considerably less than that? Looks like youd be better off just breadboarding this. Why would you want to go thru the pain of ething a pcb for this? Surely you should spend that effort not programming it wrong in the first place. Or have i missed something?

    1. Zopiclone –

      Good questions. There are a few reasons why I think the rescue shield is useful:

      1. If you’ve bricked just one chip, it probably makes sense to throw it away and buy another. But if you’ve bricked a handful then the kit pays for itself pretty quickly.

      2. A breadboarded version of this circuit works great once, but will probably be torn apart by the time you need to save the next part. The kit can be safely put away and will keep all its parts intact, waiting for the next time you need to unbrick an AVR.

      3. With a rescue shield kit in your toolbox, you’ll find that sometimes it’s more convenient to be able to fix the part you have on hand vs. buying another – especially late at night with a deadline looming.

      4. The kit is totally open source, so it’s a great opportunity to learn about the little-known HVPP/HVSP mode built into most AVR microcontrollers.

      More info here: http://mightyohm.com/hvrescue21

      PS. The link in your profile is pretty spammy, so I removed it.


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