Hi guys, can you please help me troubleshoot lm2576 power supply? I picked a Provo Craft Circuit Personal Electronic Cutter off a garage sale and it was non-functional. I traced the problem to lm2576-5.0 that takes 17V input and was outputting 0.7V. The voltage on pins 2 and 4 was identical - 0.7V. I replaced the ouput capacitor (it was 330uF originally) with a 1000uF capacitor. The output voltage went up to 1.92V.
Does this experiment mean the lm2576 is blown?
It doesn't seem to be thermal clamp as the IC is cold. Which also hints me it's not the output current clamp - if it were clamping on 3A it would get at least warm. So not sure what the issue is, please help.

 

Does this experiment mean the lm2576 is blown?

Probably not. The fact that a larger capacitor increased the output voltage likely indicates an overload condition.

I'd separate the output from the rest of the circuitry and see if it starts working. You need to maintain connectivity to the diode, inductor, cap, and feedback input when you do that.

It seems that you tried to organize your post into three paragraphs, but it looks like one rambling paragraph in my browser...

 

It's going to be hard - will have to cut some traces.
Before you posted your reply, I traced all electrolytic capacitors down the stream and desoldered them from the board with no change in behavior.

 

The fact that a larger capacitor increased the output voltage likely indicates an overload condition.

You were right. Cut the trace and there you go - 5.35V on the output... Will keep searching, thanks much for your help!