Mega STe LED colours

[Pacman]

Are there any Mega STe owners out there who can tell me the colour of the original factory installed LEDs?
Mine has a 5mm red power LED while the service manual indicates a green one (and it looks like the metal mount is made for a 3mm LED.
The internal hard drive appears to have a 3mm yellow LED, which is what mine had as well (need to change the 3mm PVC grommets though as discussed in another thread).

Screen Shot 2021-04-29 at 13.36.06.png

[Darklord]

I can't answer that but there's a lot of good stuff concerning the Mega STe's LED's
going on here (sorry if you've already seen this):

https://atariage.com/forums/topic/30093 ... nt-4437693

HTHs.

[Pacman]

Cool! New 3D-printed LED mounts for the Mega STe and TT!
Fortunately mine aren't that bad (yet), but good to know they're available.

I don't think anyone said it right out in the thread, but based on several photos and comments it appears that the repair manual parts listing is correct:
Yellow for the internal hard drive and green for power. The red 5mm power LED must have been put in by the previous owner.

[pixelpusher]

Cool! New 3D-printed LED mounts for the Mega STe and TT!
Fortunately mine aren't that bad (yet), but good to know they're available.

I don't think anyone said it right out in the thread, but based on several photos and comments it appears that the repair manual parts listing is correct:
Yellow for the internal hard drive and green for power. The red 5mm power LED must have been put in by the previous owner.

Yes the HD should have a yellow light - and all of them are 3 mm LED.

[Pacman]

Thanks for confirming :D

[Pacman]

About LED intensity.... if I want a "normal" old fashioned type intensity (like back in the 80s, originally used in the ST), how many mcd should I look for in the datasheet?
I'm not trying to turn the ST into a lamp of some sort (which is easy to do these days with the "high intensity" variants) :lol:

[exxos]

Probably like 2mcd :lol:
Easy to add a resistor in series with it if needed anyway..

[Pacman]

Haha! Yes, you're right about the possibility of adding resistors in series if the intensity is too much.

I've just ordered some new LEDs and out of curiosity (and wanting to calculate the resistor value needed) decided to check the voltage of the J290 connector (top right in schematic below) as different LEDs demand slightly different voltages.
I was expecting something like 2V but measured 5V across those pins, and that's both before and after the 120 Ohm resistor (R290).
I then reattached the LED with its connector and mesured around 1.6V across the LED pins which sounds more right.

MSTE_power_LED.png

I assume the load of the LED itself lowers the voltage, but how is one to check for a suitable voltage before the LED is attached? And without the LED attached, why do I measure approx the same voltage before and after R290 (5.033V vs. 5.032V)?

[exxos]

LED will clamp the voltage to whatever its voltage drop is.. generally around 2V.. You can be lazy with this stuff.. If the LED is to bright, just try like 500R in series and just experiment to what looks correct.

[Pacman]

Sounds good! :dualthumbup: