Simple question I hope

[The Dude]

The LED here is just a power indicator and the series dropping resistor is plenty big. No circuit is dependent on it's voltage drop. As long as you can see it light up, color and voltage drop don't really matter (within reason). Also, if you have it disassembled and don't want to measure voltage on the pads, the schematic shows that anode goes to ground, so just use your meter to see which pad is ground and solder anode to that pad. Sure you can depend on long lead anode and circuit board markings, but you can also verify everything with a DVM so that you don't end up taking it apart again. That's sort of what meters are for.

[Helmholtz]

Thanks. Looks like a white LED.

In-circuit current is about 30mA and LED should be rated for more than 100mW.

[g1]

The original LED was clear.
The new LED is white and it seems the voltage drop is higher on solid white.

As far as the color names go, it refers to the powered up color. A clear one that lights up white is called white. A clear one that lights up red would be called red. And a LED that looks white unpowered is likely called frosted white.

[Oldmactech]

D1 on the schematic shows the off center line on the PCB, the line indicates the cathode side?

[nosaj]

As far as the color names go, it refers to the powered up color. A clear one that lights up white is called white. A clear one that lights up red would be called red. And a LED that looks white unpowered is likely called frosted white.

Ever had an infrared one mixed in? I like the UV ones the best
nosaj

[g1]

D1 on the schematic shows the off center line on the PCB, the line indicates the cathode side?

Yes. In this case, the LED is running off negative supply (-36V) so anode is grounded, cathode goes to R51.

[Pixel]

Thanks. Looks like a white LED.

In-circuit current is about 30mA and LED should be rated for more than 100mW.

Excellent point. Most LEDs are going to max out at 20mA and won't live very long running at 30mA. You could put two 20mA LEDs in parallel if you can't get the right part. It would be a shame to do all this work and have the LED burn out again.

[Pixel]

Hate to be a newbie but would be interested in the science behind this LED.

White LEDS actually emit blue light and the blue light excites phosphors that emit the missing colors to make the light appear white. If you look at a white led you can see the yellow phosphors inside.

[Helmholtz]

White LEDS actually emit blue light and the blue light excites phosphors that emit the missing colors to make the light appear white. If you look at a white led you can see the yellow phosphors inside.

That's why blue and white LEDs have the same higher forward voltage of roughly 3V (depending on current).

Forward voltage matters regarding LED power consideration.

[Oldmactech]

These are the culprits. The clear one (white I guess it must be) and the white one. Clear is the original. Along with the description packaging of the one

I certainly appreciate the LED education I’m getting and as soon as I get over the Covid I came down with I’ll get back to it.

[Helmholtz]

Looked up a few Edgelec (a Chinese brand) LED data. Seems the white ones typically have a current limit of 20mA and a power limit of 60mW.
Means not suitable here.

You might try to increase the value of R51 to 2.2k to accommodate your LED but brightness will be lower.

Better get an LED from a reputable brand like GE, Cree, Nichia, Philips, Osram etc. having a suitable specification (including some safety margin).
I wouldn't buy from a source that doesn't provide a complete specification.

[Oldmactech]

Ordered these from Mouser. The Mouser rep wasn’t able to assure me it was correct for my application.

C512A-WNN-CZ0B0152
Cree LED Standard LEDs - Through Hole

[Helmholtz]

Here's the datasheet from the Mouser site:
https://www.mouser.de/datasheet/2/72...NN-3011984.pdf

Current limit (25mA) is too low. You need to increase R51 to 1.8k or even 2.2k.
Increasing R51 lowers brightness but increases reliabiliy.

[Pixel]

Ordered these from Mouser. The Mouser rep wasn’t able to assure me it was correct for my application.

C512A-WNN-CZ0B0152
Cree LED Standard LEDs - Through Hole

Increase R51 as Helmholtz indicated and you should be happy with this LED. Be sure to mount it at the same height as the original because the jewel may be dependent on the position of the emitter for focusing.

[Pixel]

You won't notice a difference in brightness between the 1.8k and 2.2k resistor so go with the 2.2k for longer life. It is puzzling why Peavey didn't go with a 20mA part. Verify that R51 is really 1.2K as the schematic indicates. Maybe it is a typo or they changed the value in production.