Ps drive wave

[mnhiphop101]

What would cause the output from a tl494 to look like this? I've tried two different chips and gotten the same waveform on both.

 

[Perry Babin]

No FETs in the amp?

Is the display inverted on the scope?

Long shots...

Pin 13 not at 5v?
Either pin 3 or 4 below ground?

 

[mnhiphop101]

Correct, no fets in amp. Is that normal? I've never seen that before

 

[Perry Babin]

If what you're seeing on the scope is accurate, it's not normal. If it had FETs in the supply, I'd expect excessive current draw.

Did you check the things I listed?

 

[mnhiphop101]

That is correct. Fets in draws current

 

[Perry Babin]

Pin 13 not at 5v?
Either pin 3 or 4 below ground?

 

[mnhiphop101]

The display is not inverted.

Pin 13 is at 5v

Pins 3 and 4 are 200mv above ground

 

[Perry Babin]

Are pins 9 and 10 identical and in phase (will have to use two scope channels to know phase)?