OpAmp suddenly quiet

[rozencratz]

I built the Mach 1 and tested it before putting it the enclosure and it sounded good. After putting it in, something happened and now the signal coming out of Pin2 on the Opamp is very quiet. I get the full volume at pin 3 so it's getting to the opamp ok but then the output of 2 is like 1/10th the volume. It also seems like maybe the A500K Drive pot isn't responding? I hear the signal appear to try and pull more gain but the tone doesn't change at all, if that makes any sense. I'm still very new to this so any guidance would be appreciated.

All voltage readings at the pins seem to be right, with 1,2,5,6 and 7 reading 4.8V and 3 reading 4.5V.

I've traced the signal through the rest of the board and everything else appears to be working properly. I replaced the opamp just in case and there was no change.

 

[swelchy]

it's very likely you have a short.. random strand of wire touching something or a small solder bridge... your soldering really needs some work.. which is ok.. we all gotta start somewhere... But you do need to focus on better soldering and how your wiring is done... You'll get there... My suggestion is redo all your wiring by unsoldering.. clean it all back up with solder pump and braid.. clean , clean, clean with 99% iso and go back at it again neatly.

 

[Passinwind]

Pin 2 is an input, not an output. What are you seeing on pin 1?

 

[rozencratz]

Pin 2 is an input, not an output. What are you seeing on pin 1?

Identical quiet signal

 

[falco_femoralis]

Intermittent issues are usually physical - one wire was in the right place and then was bumped out of place. Listen to Swelchy above - clean soldering equals reliability. Spend some time watching youtube about how to solder to boards etc and see if you can pick up some tips, then take another go at your board.

Use Superwick 426 desoldering braid to take it back apart. Remember, go slow and don't force it

 

[HamishR]

I suspect that your iron isn't quite hot enough. You should only need a second at most to make your solder connections, then they don't look so lumpy. Also the solder spreads better. You can see how the 3K3 resistor above the IC doesn't have the hole filled with solder. It should if your iron is hot enough.

Is there a cover on the pot under the board? If not that could be where your shorting out is happening.