Prop Pro Dev Board burnout - Capacitor C1 replacement

Paul_H

Hi All,

Want to know how do you check the voltage on a cheap power supply? Plug it onto you PPDB and look for smoke... Yeah that was me. I didn't test the P/S on my meter first so.... Pffffvvvtt. The good news is the board/prop/chips/etc are fine. The bad is I need to replace a capacitor. (Actually not all that bad!) This a cap C1, a 10uF on the PPDB schematics.

My question - What type of cap should I use to replace? Polarized? Ceramic? What tolerance, etc

I know I could slap any 10uF in place and be fine, but I am glad this particular one blew and warned me through smoke signals, so a similar/identical replacement is a good thing.

Thanks!
Paul

Mike Green

A 10uF 16V aluminum or tantalum electrolytic capacitor would be about right. The recommended input voltage for the Protoboard is 7-9V as I recall.

Dr_Acula

Just make the working voltage on the capacitor higher than the volts you will apply. The cap volts go up in discrete steps, eg 6.3V, 10V, 16V, 25V, 63V. So pick a voltage a bit higher than the power supply. An unregulated 9V supply might go to 11 or 12V, so this is why Mike has picked 16V as it gives a bit of a margin.

jazzed

Rule of thumb from years ago is 2x expected voltage except when your capacitor would be bigger than a bread basket.

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--Steve


Propalyzer: Propeller PC Logic Analyzer
http://forums.parallax.com/showthread.php?p=788230

Paul_H

Thanks guys!

kwinn

jazzed, we must have the same rule book. Mine has 2x in it quite a few times.

Toby Seckshund

There seem to be a few simular threads on "high volts from cheap PSUs. Here in the UK Props are NOT $8, so a few more checks are wise. Tant caps will burn a hole right through the PCB if the go!

Once, I did use the right volts , just a bit backwards though, Prop survived, bless

Toby Seckshund

Thinking about it If the volts are far that high the regulators could burn ...