Mach 1 (Greer Lightspeed) - No Signal when Stomped On

Hi,

I finished up a Mach 1 PCB tonight and am having some troubleshooting issues. When powered, the LED does come on. True bypass does pass through the cables and to my amp. However when stomped on, all sound cuts. I have checked for any grounding out and have tried it both outside and inside an enclosure. I tried swapping the OPA2134 IC with a TL072, but had the same issue.

Below are several photos of my (sloppy) build. Forgive the very shoddy job - I'm still learning the art of this ha.

I took several photos so I linked them to an album here, instead of having 14 photos spam several screen scrolls.

Edit: here are additional photos of it outside of the case after trying a new switch and without a breakout board; disregard the power jack not being soldered in these photos; it's only because I had just taken it out of the case.

Any help would be great.

Thanks!
 
Last edited:
Hi,

I finished up a Mach 1 PCB tonight and am having some troubleshooting issues. When powered, the LED does come on. True bypass does pass through the cables and to my amp. However when stomped on, all sound cuts. I have checked for any grounding out and have tried it both outside and inside an enclosure. I tried swapping the OPA2134 IC with a TL072, but had the same issue.

Below are several photos of my (sloppy) build. Forgive the very shoddy job - I'm still learning the art of this ha.

I took several photos so I linked them to an album here, instead of having 14 photos spam several screen scrolls.

Any help would be great.

Thanks!
I think you may have Solder bridging under the Footswitch Breakout Board!?
Can you test your Footswitch for Continuity
When ON, Only the top pads & middle pads in Black should have Continuity
When BYPASS, Only bottom pads & middle pads should have Continuity
You should have no Continuity between side pads & middle pads in any position straight across!
Footswitch.jpg
 
I think you may have Solder bridging under the Footswitch Breakout Board!?
Can you test your Footswitch for Continuity
When ON, Only the top pads & middle pads in Black should have Continuity
When BYPASS, Only bottom pads & middle pads should have Continuity
You should have no Continuity between side pads & middle pads in any position straight across!
View attachment 30714
Thanks for the reply!

Just ran a meter across what you said and that’s gotta be it. When ON, I’m getting continuity between the middle and middle-bottom pads.

Gonna take this breakout board off and try another or without it at all. This is my first time using a breakout board so I’m not surprised I made an error with it.

I’ll follow up with results. Thanks again.
 
Just gave a new switch a shot and still no luck. I wired it up manually and without the breakout board. When cranking the volume knob I can hear a slight increase in general amp noise, but still no signal at all. And as I said, the signal passes fine when the switch is not engaged.

Could the two 22uF electrolytic caps be bad and causing this?

Thanks again.
 
I took some additional photos of it out of the enclosure to show both sides:


Please disregard the power jack not being soldered in these photos; it's only because I had just taken it out of the case.
I would try & Clean the back of the PCB, lots of Flux & Debris needs to be removed & under the Tone pot
I'm not going to Lie, you seem to have too much Heat in your solder in general.
What Voltage are you getting on your OpAmp pins?
1..........8
2..........7
3..........6
4..........5
 
I would try & Clean the back of the PCB, lots of Flux & Debris needs to be removed & under the Tone pot
I'm not going to Lie, you seem to have too much Heat in your solder in general.
What Voltage are you getting on your OpAmp pins?
1..........8
2..........7
3..........6
4..........5

Thanks for the reply. Tomorrow i’ll work on getting the surfaces cleaned up. And don’t hold back on any criticisms, I still have a whole lot to learn. I did these at 785F, what’s a good target temperature I should use?

Measured the pin voltages:

1-8: 4.14V
2-7: 0.04V
3-6: 0.0V
4-5: 5.05V

Thanks again!
 
For the opamp pin readings, take your black probe to ground (alligator clips work best here but not 100% necessary) and touch the red probe to each of those pins on the other amp. @music6000 was showing you how the pins of the opamp are numbered.

You’ve only provided half the pins.
 
Plug your amp into the output jack. It should already be grounded via the pcb. Clip one end of the alligator clip to the Jack's tip. The other end of the clip goes to one of the leads of the capacitor. The remaining lead is your probe. The capacitor filters out any DC signal.

Trace the circuit until you find your dead spot. You'll need to be able to read a schematic. The dead spot is your problem area unless that part is grounded.
 
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