DIY Pedal Attempt

[whitebison66]

Yes, the polarity was the culprit.

It may also have been the resistor, which I changed, so now I have LED.

Naturally, my first instinct is to go after the AC and see if I can get it working (especially since I'm not sure the 9v will fit in the enclosure, as I didn't plan for it when I laid out and drilled the control holes.

 

[Cagey]

Probably wasn't the resistor, but maybe so.

I remember about 100 years ago I worked for an industrial electronic controls company and we came out with a new product that was revolutionary in the industry. Unfortunately, it had a LOT of problems, not the least of which was an I/O board that regularly burned up in a matter of days. Unbelievable. The techs caught it first, seeing it happen over the short time it took, and it turned out that somehow the Bill of Materials called out 33 ohm current-limiting resistors for some LED indicators when they should have been 33K (or 330K, I don't remember). They didn't exactly burst into flame, but it didn't take long before they got so damn hot they burned up the PC board beyond repair. I don't know how they ever got past the test department. Damn things must've been as bright as the sun, and this was long before LEDs were considered illumination.

It's the little things...

 

[whitebison66]

Okay, we have success... of a sort.

I abandoned the idea of a separate adjustment pot and used the stock one, decided to go with 9v battery power since that worked and the adapter didn't, and I think I'll just use the pedal as-is without paint. Maybe a simple black decal; working on that as we speak.

The LED was working, though you could turn it on without a cord in the jack. Went back to check and its not working. Noticed it would flicker back when it was lit, so maybe it's a resistor issue?

Bottom line is that it works, which is still a quantum leap forward from this morning.

You can see the clearance issue with the knob, but that's a minor problem.

The interior was a bit more cramped than originally intended because of the battery, but I got it to work. Not the best wiring job in the world, but it's better than it would have been last year, so I'm improving.

 

[NQbass7]

Flickering is pretty much 100% guaranteed to be a bad connection or a loose wire bumping against a bare connection or wire. Make sure you don't have any cold joints (kind of hard to tell from the pic), and make sure the LED wires can't bump each other (I often use heatshrink tubing to protect bare LED leads).

 

[Cagey]

Something I was surprised to learn not too long ago is that most DC adaptors for pedals have what I would consider a backwards connection at the connector. They make the barrel positive and the pin negative. Since the barrel is heavily exposed, you would expect that to be the ground/common connection, with the positive connection protected from casual contact inside the plug or at the tip. So, you may want to check your polarity there.

I agree with NQBass about the flickering LED. Too little current flow because of an improper resistor would just make it dim, not flickery. You've more likely got a loose connection due to a cold solder joint, or it's on the hairy edge of shorting out to something. For as tight as things appear to be in there, the short theory gains weight.

 

[whitebison66]

Latest update: Fixed the LED issue with lots of heat-shrink and careful soldering. I noticed that I had two styles of LED, and that the ones with  shorter legs worked and the longer didn't. I didn't end up with the LED color I hoped for, but that's really not a big deal.

I'd need to run one of the battery wires to (through?) the input stereo jack (I assume) to stop the LED from turning on without a cable in the input jack, but I think I'm going to still try and get the AC input jack to work.

As Cagey noted, FX pedals have 'reversed' jacks. Luckily for me, I can order some from eBay that are located about 5 miles away and have free shipping.

In the meantime, the pedal works, so at least I'm able to amuse myself.

 

[Cagey]

You shouldn't have to change the jack, just how it's wired. Make the barrel connection positive and the pin connection negative. Or, change the polarity of the plug on your power supply. Either way will get you there. The main consideration is that all your effects are the same, so if the one you're dealing with is the oddball, make it conform with the group.