Capacitor pop - why?

Well, Scott Lee got back to me with the following info:

"ps I think the supplies we have been sending are 200mA InterAct brand
and the wire with the markings on it is the plus."

So... that means the white striped wire is +

My multimeter hasn't come yet, but I'm impatient so I flip-flopped the wiring (switched + and - wirings) and replaced the capacitor and it STILL doesn't work. Unless there is something wrong with my LED. It doesn't light up at all. EITHER wiring causes no LED light. This time I didn't wait long enough to see if something would explode.

I'm getting pretty baffled (and a bit frustrated... at this point, I've put a lot of work into the project)

Guess I'll have to wait and test everything out once my multimeter arrives.

Never mind! Got it fixed... not sure what was wrong, but it seems like the central switch wire (to ground) was loose in the lug (the 3-wire ground lug; the solder wasn't solid for the switch-wire)

Once I made sure it was all snugly on there (with a big ugly solder blob), I switched it on again and the LED lights up! Very exciting stuff (hey, after countless hours and several hurdles to jump, getting an LED to light is amazing news!)

Not gonna get my hopes up too much, but at least it looks like the board is getting power and the capacitors aren't exploding, so I'm off to try to calibrate/tune it and see if I can get some sound out of it...

I wasn't so lucky. While reconnecting the wires from the power supply, I managed to overheat the switch, and it needs to be replaced. Turns out the LED I used (a nice green one from an old PC) was old enough to use a different standard for polarization. It was in wrong by modern standards. When it failed to light, I suspected the power supply, and reversed it's polarity. That's when things went south on this one. And it's what went wrong according to Scott.

Soooo, out comes the board, the capacitor, and switch. Now, I just have to reset the power supply to what was originally correct, insert the LED the right way round, and replace the C1 capacitor. And pray.

That'll teach me to use non-standard parts. lol.

Yeah, that stinks...

BTW, I too swapped in a green LED instead of the red one, but it was a fresh one I just bought so I guess it was up to spec.

(I built this all into an Atari 2600 case, and the LED is actually inside the case, viewed through a clear lexan panel, so I felt like the green glow looked better than the red one)

Now I'm having troubles with the tuning and calibration, but that's for another post...

I can't wait to see a theremax in an atari 2600. I've seen one in a nintendo before on youtube. Pretty cool.

Regarding your tuning problem, did you put a sheet of metal under the circuit board?

Scott at PAIA is sending me a replacement capacitor, along with a switch assembly. In the process of desoldering, and resoldering the power connections to the switch, I managed to overheat the switch as well. It's literally fried mainly because I tend to stay on a part too long while soldering due to my low vision. It's hard for me to know when the solder is flowing right.

However, in return for me doing a theremax demo on youtube for PAIA, Scott went ahead, and prewired the switch with extension pigtails, a new resistor, and LED so I don't have to worry about overheating the switch in the future. Hopefully, I'll have first sound by the end of the week, or so. ;)

Yeah, I have a sheet of metal (well, aluminum foil, so it's a little ghetto, but it is there, hot-glued to the bottom of the case and connected through the board risers and ground lug.)

Ok, rulling that out, and knowing how small the Atari 2600 case is, I'm wondering if the size of the atari 2600 case is some how bringing either the antennas, or the antenna leads too close to the circuit board, or something.

Still wondering why you want to use an Atari 2600 case. It's not the most attractive thing I have ever seen.

Was it just something you had lying around to put your theremin in?

Lucite (i.e. plexiglas) is fun stuff to work with and you could make a really nice case for it out of lucite. You could even use the clear stuff to show off your handwork inside. Just a thought ...

Don

Personally, I am leaning towards something out of wood that looks remotely like a RCA.

Lowes has some very nice looking screw-in wood legs to make the thing more transportable.

I could even make a compartment to stow the antennas in for transporting it.

Getting way ahead of myself, though. Got make a working theremin first.

Don