# Parentheses OP07CP signal loss



## tmfoh (Nov 28, 2019)

So I'm having a nightmare with my parentheses build. I think this must be the 3rd big problem I've had. Anyway, the problem is I'm getting an intermittent signal out of the OP07. Sometimes I'll turn the pedal on and it'll work then after a power cycle it won't. It jumps back into life if I short the output pin with VCC which isn't great but it does the trick.

IC voltages
Not working                     
1 - 8.62                                
2 - 1.30                               
3 - 0.50                               
4 - 0                                  
5 - 0                                      
6 - 1.33                               
7 - 8.69                                
8 -  8.55                                

Working
1 - 8.61
2 - 2.28
3 - 0.50
4 - 0
5 - 0
6 - 7.02
7 - 8.71
8 - 8.61

Any ideas as to what I could try? My only other thought was to try the OP07 CPZ


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## zgrav (Nov 28, 2019)

could be a cold solder connection.  might or might not be right at the OPO7.  shorting the output pin at VCC may be enough to force the connection to start somewhere else in the circuit.  take a close look at your board and reflow any connections that look dull or questionable.


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## falzhobel (Nov 28, 2019)

I only had trouble with this built. Mine was cold solder into the gain stage... Also, the Octave is not working very great, even after matching the GE diode.


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## tmfoh (Nov 28, 2019)

I've reflowed once already but I'll go over it all again. Does it make a difference that i still get the same level of input to the OP07 no matter fi it's working or not?


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## Chuck D. Bones (Nov 29, 2019)

Those OP07 voltages are wrong, working or not working.  Pins 2, 3 & 6 should be close to +4.5V.  Make sure all of your resistor values are correct.  Check the voltage at the bottom end of R8.  When using the OP07 as a sub for LM308, you should omit C12.  Show us some pictures.  Do a close-up visual inspection.  Blindly reflowing solder joints is hard on the board and components.


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## Nostradoomus (Nov 30, 2019)

Yeah the op07 is internally compensated, but it really doesn’t sound any different if you leave the cap there.


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## Chuck D. Bones (Nov 30, 2019)

Maybe so, but I don't like putting parts where they don't belong and the datasheet says nothing about what happens when a cap is put between the balance pins.


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## Nostradoomus (Nov 30, 2019)

Fair enough! It seems like nothing happens haha. I’ve made a few rats and realized I have no more 308s so subbed the OP07...nothing odd so far haha


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