[XCSSA] Blowing Fuses and Unsure Why

[X-otic Computer Systems of San Antonio]

On Jan 8, 2009, at 6:34 AM, X-otic Computer Systems of San Antonio  
wrote:

>
>> The 9VDC half...well, seems to work for a few  seconds and then
>> blows a fuse. I'm not sure why. I've got LEDs (with  resistors)
>> hooked up to each output and, for some reason, the 9VDC
>> lights up for a few seconds and then my fuse blows. Everything looks
>> connected properly but there is no load on either side except for the
>> LEDs.
>
> LED's use only a few mA (depending on series resistor), take a look
> at your filter capacitor(s) on the 9Vdc section. Carefully lift the  
> ground
> lead(s) to isolate them, also check their voltage ratings.  Sounds  
> like one
> of them is breaking down.

That's not a bad idea. I'll try that and see what happens. Trouble is,  
I don't have that many fuses :) I suppose I can just lift them all and  
put them back in one-by-one or something like that. All of them should  
be sufficiently rated as they are between 25-63V, but I'll try  
isolating them. It's certainly possible that it could be my terrific  
prototyping board skills (which are anything but :) though I didn't  
run into any shorts.

>> I'm thinking it has something to do with grounding. I haven't    
>> connected
>> the grounds on either side and I'm guessing that might be my   
>> problem?
>> does it matter where I connect the grounds together?
>
>  No, providing you're using supplies isolated from the AC line..
>
> Hard to pin point without seeing your schematic.

No problem there :)

http://www.moocowproductions.org/temp/pwr-brd.sch.png

X1 is form the xformer. Specifically, X-1 is the center-tap. X2 hasn't  
been attached to the board yet. Want to get to making the LEDs light  
up first.

Thanks for all the help (as always)!

Tim