PWM - Nothing Changes! - Help!

Hello,

I maked the circuit at Article 28 (http://www.eleinmec.com/article.asp?28) on a PCB board.

Checked all connections and components.

When I turn ON the circuit with 12V the CPU Fan don´t change its speed.

I checked the voltage at motor with the potentiometer adjusted to MIN. and was 10.32V, and I adjusted the potentiometer to MAX. and the voltage changed to 10.42V

I don´t Know what is the problem!

I strongly need a HELP to make the circuit work OK.

Thank You Very Much!!!

Julio Becker (From Brazil)

Posted by Julio Becker (julio@cncmania.com.br) on 07/01/2009, at 21:55 GMT

PWM nothing changes.

I would carefully check the track side of the veroboard for incomplete track breaks and solder bridges.Use a magnifier glass with good lighting and possibly run a stanley knife blade between each track to clean away small end of pin sized solder splashes.

Posted by Robert Neill (varient412@yahoo.co.uk) on 25/01/2010, at 10:14 GMT