DIYstompboxes.com

Projects => IC-based Overdrive => Topic started by: Guitarist335 on August 18, 2020, 05:28:48 PM

Title: How can this be?
Post by: Guitarist335 on August 18, 2020, 05:28:48 PM
I have built this circuit a few times, and successfully.

This time around however, i decided to change the op amp and use the 4558D op amp.

While I was building it, I was paranoid about building the voltage divider part of the circuit, and so i tested it with a meter along the way. It was sending the correct voltage.

I built the entire circuit and the meter measurements from the negative terminal of my 9 volt battery, and the various pins, seemed to be okay. (I shorted pin 6 and 7) to disable the second part of the op amp.

But all of a sudden, without my changing anything, all of my measurements from all the pins on the op amp, shot up to over 8 volts. Even Pin 4 , which is suppossed to be ground, is over 8 volts. 

How can this be? Even the point of the volktage divider where it should read half the voltage, is over 8 volts. See attached pics (my build, front and back and the schematic i am building from)

P.S. Here is the datasheet for the op amp.  https://components101.com/ics/lm4558-dual-op-amp-pinout-datasheet


I did not know what to do with Pin 5. Was I supposed to send that to ground- is that what could have caused this?

Thanks for your time.


(https://i.postimg.cc/Ln9bCxCh/IMG-4455.jpg) (https://postimg.cc/Ln9bCxCh)

(https://i.postimg.cc/RWqb9NzB/IMG-4456.jpg) (https://postimg.cc/RWqb9NzB)

(https://i.postimg.cc/KR0sdtwf/Screen-Shot-2020-06-22-at-10-21-12-PM-3.png) (https://postimg.cc/KR0sdtwf)
Title: Re: How can this be?
Post by: 11-90-an on August 18, 2020, 09:43:53 PM
How’s your battery?

I think you may have some shorts in your board... try reflowing
Title: Re: How can this be?
Post by: bluebunny on August 19, 2020, 06:32:53 AM
Sounds like you may have lost your ground connection.
Title: Re: How can this be?
Post by: Guitarist335 on August 19, 2020, 06:44:51 PM
Thanks guys.  Will check it out