Prop Professional Dev Board -- What is this Capacitor?

Sal Ammoniac

I did something really dumb. I went rooting through my junk box looking for a wall wart to power my Propeller Professional Development Board and found a 12v unit with the proper size plug. Unfortunately, I didn't check the polarity of the plug (it was center negative) and when I plugged it into the board and flipped the power switch, one of the caps on the board let out the magic smoke.

I found another wall wart with the proper plug and the board works fine, so I guess I didn't cook anything important. The cap itself is fried to the point that I can't read the lettering on it to determine what to replace it with.

Would someone who has a PPDB look at the cap circled in red on the attached diagram and let me know the value, voltage rating, and type of this cap?

Thanks.

Mike Green

There are only two capacitor values around the voltage regulators. Look at the schematic for the PPDB. There's a 10uF input capacitor for the 5V regulator, probably rated at 16V or 25V. That's the one that probably smoked out. The regulators probably protected the other two. There's another 10uF capacitor, probably rated at 6V or 10V and a 47uF capacitor, probably rated at 6V.

Roy Eltham

Here's a close up picture of my ppdb in that area.


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Phil Pilgrim (PhiPi)

You may also have to replace the 5V regulator. LM1086s don't have reverse battery protection. Hopefully, it didn't propagate beyond that point.

-Phil

TimH

Sal

Did the same thing myself a while ago except I used an AC wall wart instead of DC. I just replaced that cap and all has been OK since. Not sure if reverse polarity would cause the same problem.

Tim