P2ES Rev B red LED & Could not find a P2 on port /dev/cu.usbserial-...

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  • evanhevanh Posts: 8,998
    edited 2020-02-16 - 05:31:46
    Well, I managed to plug my glob-top revB Eval Board into the bench-top supply in reverse with current limit of 3 Amps. It smoked a little. :( Subsequently draws over 500 mA at 5 Volts when idle.

    After some testing I decided it was only the AUX USB power switch (U603) had failed. Next step was working out how to remove the IC with that thermal pad on the bottom. Peter had said he placed these type in an oven to soften things up so I figured I may as well start experimenting now ... using the kitchen cooking oven, set to 200 ish degC ... but of course it went much higher when I wasn't looking!

    The thermocouple desoldered from the rear of the Eval Board and was reading 234 when I next looked. Eek! I quickly whipped it out and used the at ready soldering iron to remove U603. It didn't need any extra heat though! I left the Eval Board to cool at this point ... the board was smoking a little and the dip switches have gone quite brown. :(

    Later inspection revealed the solder at the ground pegs had also liquefied. The towel I placed the Eval Board on now has a scorched square shape in it.

    But testing reveals all is good again. Well, as good as not having AUX-USB available for high power testing at least. :)
  • Evan,
    Peter uses a toaster oven with great success. Perhaps they have better temp control because the internal space is quite small, and you’re not getting solder and flux fumes in your cooking oven either.
    I have a commercial IR oven which of course has proper temp control with the appropriate temp ramps and time. The only part that isn’t nicely controlled is the cooling ramp as the fans don’t bring it down quite as fast as the preferred IC graphs show. It’s all automated which is nice.
    But it’s not the best way to desolder tho.
  • Yeah, I should get something more suitable.

  • If you have the bucks... http://www.zeph.com/

    Dont let the sticker-shock of their full-monty bundles scare you. Just their airbath under the board, combined with a small, cheap Amazon heat gun on top, works wonders. I havent found any real need (yet) for anything else.
  • Those are open air operating right? So, then one can work on the board while it's bathing? That would take much of the time pressure away.

  • @evanh Yes. They just blow hot air upwards. They are a glorified heat gun with tight control on the exit temperature and on the ramp rate. Yes, you can work on the board as it is heating. The board holder is pretty solid. It does a good job positioning the board over the heat zone and it will take some mild crashing and banging without complaint.

    The Zeph is the easiest reflow system I have used. You can set the base for 30 degrees F less than the eutectic point, and the flux activates. Then when you add-in some heat from above, the paste flows. If reworking, use Chip Quik and the components come off pretty cleanly. Only a minimum clean-up of the pads is needed. With minimum practice and a pencil-type hot-air reflow setup on top (I use an X-Tronic 9050-Pro and love it), you can pick off a single 0603 SMD without disturbing (or reflowing) any of its neighbors.
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