LED change in BOSS

[Bernardduur]

OK; here's the thing:

I changed the LED in my Boss GE-7B into a blue LED (3mm blue LED, not clear) and I had the problem that the blue LED woulnd not light up. I changed the ACA mod and now the red LED comes on perfectly and works.

Now the issue: when I use a blue LED I can't get it to light at a normal level, only very dim. I tried changing the LED's resistor to 1k, this made the dim light a bit (a tiny bit) more bright, but still to dim. I also tried lower values, still no real lighted LED.

So I tried to get out the zener diode next to the LED resistor. Now the LED works great and is very bright, but now the switching does not work (the pedal is always in the "on" position).

So:
- The blue LED differs from the red LED (stock)
- I need the zener for the switching

What kind of zener should I get as a replacement for the taken away one?

[343 Salty Beans]

You did try using a few blue LEDs rather than just one, right? It could just be that single component.

[Bernardduur]

Yes, I tried.....

But now something different; the LED comes on and goes out, but I guess my DC jack is causing the problems. Without any strain on the DC jack I get a normal on / off ; when I put strain on the DC jack (as by tighting down the backplate with the plastic cover) it won't switch on / off but just stays on.

I can also trigger it by pressing on the DC jack

Edit: problem was semi solved by removing the foam under the DC jack; now it comes on every now and then and does not go out.

[George Giblet]

The blue leds have a higher voltage drop.  That voltage drop plus the battery low zener voltage is now too high.

What you have to do is reduce the zener voltage so that

blue led voltage + new zener voltage  = old led voltage + old zener voltage

If the blue led is about 3.5V and the red was 1.7 you will need to decrease the zener voltage by 3.5-1.7 = 1.8V.   Use measured values for a better estimate and measure your zener voltage to make sure it's as expected (it could measure a little lower than what is on the label).