Modding Ok me PWM controller dont work :/

Made a 3 channel PWM fanbus - and it dont work

1 of the channels did work for about 10 seconds before I heard a pop, and no more channel. Now it just gives a constant 12V output.

This is the same for 2 of the ICs, the 3rd just gives nothing out. I try swapping the ICs about the different channels, and the problem follows the IC.

Any suggestions? Also should the IC's be getting hot? (60+C)

Ian

 

would it help if I were to post pics?

 

The ICs should not get hot. It sounds like you may have mis-connected something. Post some close ups so I can see what you have done.

 

I put all 3 channel's circuits onto one board so didnt use your exact layout... but when it all didnt work I destroyed strips so that only 1 of the channels (as photographed) was connected - so dont worry about anything off the side of the photos. Uploading pics, they'll be here in a minute

 

Apologies for size (150kb each) and repetition of photos, just uploaded all of em as I'm in a rush

 

BTW I cut the diode out to see if it made any difference - none thats why the diode leg is broken

I'll be on ICQ this evening if you got the time for a quick chat mate!

Cheers
Ian

 

Crikey!! You are brave putting 3 circuits onto a single strip of board..

Its hard to tell what the problem is just by looking at them...I have built 4 of them, I have had a couple of problems with 2 of them....

First problem being my soldering and the solder arching to the another copper strip...also, 1 of my chips burnt out as i had put it into the socket the wrong way round...doh.....

I think the best cause of action is to cut the boards into seperate pieces and test individually.

ice.

 

I have a whole new set of components on their way - I dont trust my components, have a feeling I may have blown one or two, and even with hours of testing I may never find my problem, so this time I'll do them exactly as per macroman's article

 

right - in an attempt to clear up the picture in the article, I created the following image - please tell me if I got it correct:



I think R3 is incorrect in my drawing, although thats what it looked like to me on the article (very hard to see!) I suspect the resistor is supposed to go to the base of the transistor, not the collector

Edit: Now it should be correct with R3 going to the base

Ian

 

Image for comparison BTW is this:

 

The resistor, (R3 in you picture) goes to the base not the collector. It's actually labelled R4 in my circuit!!! (don't ask!).

The labels on my pic are not very clear, (they were until I compressed the image). I will try and make them clearer when I get a chance.

Remember what I said about the pencil!!