Help my Buffer won’t bypass!!

[SirHugo]

Hello all,
I've recently built a GGG single buffer, and it's not working correctly
So far as I can tell it's wiried correctly (super low part count).
Here's what's happening, the LED lights but it's not allowing signal to bypass.
I've changed 2 components and I'm not sure it that would cause and issue or not;
1. I swapped the stereo input for a mono as I can't fit a battery in the enclosure,
2. I couldn't find TL071 so it has a TL072 instead.
Here are my Multi meter reads:
R1 4.00 - 8.86
R2 4.00 - 0.00
R3 1.86 - 0.00
R4 0.00 - 0.00

C1 4.00 - 0.00
C2 0.00 - 0.01

IC1 0.03 - 0.19
      0.18 - 8.88
      4.03 - 0.85
      0.00 - 0.92

Power  8.88 - 0.00


Thanks ahead of time for your help!
-JHK

[tonyharker]

TL072 will not work in this circuit.  The TL072 has 2 op amps in it, you want a chip with only one.  The TL071 has only one op amp in it.

[GibsonGM]

TL072 will not work in this circuit.  The TL072 has 2 op amps in it, you want a chip with only one.  The TL071 has only one op amp in it.

Just a point for clarity.....The reason this won't work is that the board was etched for a single opamp....if you were making this on a breadboard, or building on perfboard, etc,  you could use a '71 OR '72, as long as you accounted for the different pinout and terminated the unused opamp correctly.   Each one functions independently, just has separate inputs & outputs.   

Like Tony said, best to get yourself a single opamp with the pinout of a TL071...

[SirHugo]

Ah I see, that makes sense.
Is there any way either the opamp may be
Damaged from plugging it in the way it has been?
Thanks so much guys, this was a huge help!
-JHK

[antonis]

It depends on IC's right output (pin7) BJTs complementary pair ability to withstand the 8.8V V_BE reverse bias voltage..

In any case, you'll have, at least, one healthy op-amp.. 

[patrick398]

Just to point out, there are many single opamps you can use, you may have a suitable one laying around, doesn't have to be tl071. LM741, tl061, tl081, LF351, and loads more

[SirHugo]

Awesome!
Thanks you both so much.
I'll dig though and see what kinda spares I've got laying around.
-JHK