Lol ok
On the PCB,
-both channels don't seem to put out current, not high power consumption. the output is 0V. Basically does not respond to input on either channel, you get some feedthrough of the signal (same as powered off) on the output.
on wires with the SK diodes at supply.
-1 amp on both chips works. the other amp is at rail voltage, Does not respond at all to any activity on the non inverting pin. . they can smoke a resistor. if you connect a resistor to the railstuck output pin, it gets serious juice through it. The other side of the amp gives output proportional to input.
IDK if the supply is causing a channel to seize. The board has lots of decoupling (good capacitors) and diodes right near the chips.
But it seems if I do the same experiment where i short out the feedback path to make a inverting amp, its not putting out current.
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
so IDK if anything is even broken. Maybe?
when I try it from the PSU I have the 2 SK diodes on each channel and then a long tight twisted pair of 18 AWG wire connected to graBBERS. Maybe I need local decoupling or something. I think I need to buy another socket, and make a test PCB with some decoupling capacitors.
![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
christ, this is about as easy as starting a old chain saw
Maybe I get the old HP dual supply with the 'tracking' function out. Then raise the voltage slowly for the chip.
bcause the version of this circuit that worked was
1) older amp
2) protoboard
3) decoupled pretty good (tantalum and ceramic). The PCB version is ceramic and electrolytic polymer (did not want tantalum).
4) same power supply
Maybe it does not like ground planes or something but still wants decoupling?? or tantalum caps? maybe I made the rail decoupling ESR too low, I did go kinda crazy with it....