TL072, Is it backwards ??

[crunchman]

Trying to hash out an fx loop issue, voltage in/out are per specs.I'm wondering if the ic chip is not inverted, but wouldn't that skew the in/out voltage readings??

Can't imagine what else is wrong, pretty simple board here.The guitar signal travels through the board based on the bypass switch working, but does not reach the send/return jacks.

[loudthud]

TL072 uses the standard dual opamp pin out. Output are 1 and 7, inverting inputs are 2 and 6 and non-inverting inputs are 3 and 5. Positive supply is 8, negative supply is 4.

[Jazz P Bass]

The little notch on the ic is considered the top. ( sometimes a round depression at pin 1)
Pin 1 is on the top left. Down through 2, 3 & 4.
Pin 8 is on the top right. Down through 7, 6 & 5.

[crunchman]

Thanks for the input guys. There is a circle that is molded into the top of the case, if that represents the top I have on the lower right, it sits between

what would be pin1 and 2.

[tubeswell]

There is a circle that is molded into the top of the case, if that represents the top...

which it does

[crunchman]

well, the pcb has the components in outline form, the ic spot has a notch on the bottom and thats where I put the circle.So I have to assume its correct.Again, all the voltages in/out are ok.I tried to track the guitar signal with me M.M. as I have done this before but had no sucess, won't read anything set on 200-AC ??

Back to the drawing board, I really need to learn how to "effectively" read a schematic...........Thanks again.

[Steve Conner]

If it was in backwards, it would get hot and blow up.

I think you have the pins confused, if you place the chip so the notch is at the top then pin 1 is to the left and pin 8 is to the right. The pin numbers start in the top left corner and count up anticlockwise.

Edit: some chips have a little dot next to pin 1, and I can see how that might look like it was between pins 1 and 2.

The 200 volt range on a multimeter is a bit
too high to read signals out of an op-amp. Try 20 or 2.