Search results

Thanks for the reassurance and all the help @Chas Grant

Hard to see in the photo, but the black wire coming off the sleeve lug of the output jack is my enclosure ground. It gets sandwiched between the back cover and the screw when I close the enclosure up. Any thoughts on the op-amp? Could it be as simple as wear end tear on the pins going in and out...

I reflowed and added solder to R101, R102, any other resistor providing bias voltage and any other joint that looked suspect. This got me proper VDC on the op-amp and sound when the effect was activated, but it was quiet and sounded shitty. Switched out the op-amps and it sounds perfect. Before...

Here ya go

The tone pot blocks a lot of the joints on the back of the board. Should I remove it for the pictures/troubleshooting?

No DC from tip to sleeve on the input jack, and unfortunately the aforementioned cheap DMM only reads resistance up to 2K and doesn’t really give a reading on any of the resistors I tried

I checked the voltages. Viewing from the silkscreened side, the left pin of R101 reads 8V and the right reads 3V. Sorry if the numbers are imprecise, I’ve got a cheap DMM that only reads whole numbers for VDC.

I’m having some issues with a Mach 1 I built for a buddy of mine awhile back. This is the same pedal that had the screwy gain pot. I replaced the pot, tested the pedal, retested it, then tested it a couple more times for good measure, and everything worked fine. Take it to my friend, we play it...

I finally got it solved. I had strong suspicions about the gain pot so I elected to work on that first. Pulled it out, scrubbed the pads with IPA, popped a new 500K in, fired it up and it worked like a charm. Sustain for days and no fartiness or gating even with the drive pegged. Thanks @Mcknib...

Yeah I’ve tried switching the TL072s out (don’t have any other dual opamps on hand unfortunately). I even tried the TL072 from the functioning pedal in the non-functioning one just to rule out a bad device. Could a melted gain pot cause this issue I’ve been having?

Ok so the meter I got only gives VDC read outs in whole numbers but here they are (all pots on the pedal maxed): 1. 5 2. 4 3. 2 4. 0 5. 5 6. 5 7. 5 8. 8 While I was at it I took the voltages from the pedal that is working right for reference: 1. 4 2. 4 3. It was switching between 1 and 2 (so...

Here are the photos. The pedal passes sound in bypass and the LED works fine. Not sure how to measure the IC voltages though (total noob here)

Hi all, I've been working on a pair of Mach 1's and have an issue with one of them that I'm having a hard time diagnosing. The pedal works normally throughout the full sweep of the volume and tone pots, but with the gain pot the sound starts to gate and fart out as soon as you go past noon-ish...