On the bench this morning... fixing it or completely fuxxoring it.Last night, while working much more tired than than I should have allowed myself, I tried to set up a bookshelf which I'd just cut cable management grommets into. Everything went fabulously; nice and tidy and neat... until I plugged my large digital picture frame in.
KAAA-ZZZAAAAP! POP! SMOKITY-SMOKE!Turned out I'd grabbed the charger for my eBike out of the wrong drawer and dinn't even look at it twice; it's a CV/CC power pack that puts out up to 29.4V/2A.
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=898096;image)
So, after exhausting the usual culprits (turns out the smoke was a 470uF/16V electro that didn't like 2x rated voltage) that could easily be tested with just a meter, I decided it was time to track down the shorted
whatever that remained the low-tech way: apply a current-limited power source set for the lowest voltage device on the board and see either A) what still gets warm or 2) if that doesn't reveal the diseased part, start looking for the device with the lowest measurable voltage dropped across its power pins. This is generally much quicker and able to resolve much better than trying to measure resistance. A quick look at datasheets indicates everything is 3.3V or higher... so set my power supply at 3.3V/400ma.
Right now it appears U10/THC63LVDM83R (a clone of TI DS90C383BMTX TTL/LVDS converter) is our main victim; with the low-noise LDO feeding it getting a little warm but barely. Next will be to desolder it with my cheap Chinese hot air gun, and if this removes the short, see what happens when I replace that
bd139-ified cap and 3.3V regulator to the uPC.
![Wink ;)](https://www.eevblog.com/forum/Smileys/default/xwink.gif.pagespeed.ic.cldandycH0.png)
Boy, I'd love a sanely priced IR camera for this kind of work...
![Shocked :o](https://www.eevblog.com/forum/Smileys/default/xshocked.gif.pagespeed.ic.CrwtrNUjLO.png)
mnem
tzzzzzzzzzt!!!