SSlmixed.com Forum

Tech discussion => 4K,6K,8K Series => Topic started by: tlmaen on January 23, 2025, 08:52:11 AM

Title: Original Channel LED specs
Post by: tlmaen on January 23, 2025, 08:52:11 AM

Hi,
what are the original LED specs in the Channels (green, red, yellow)?

Thanks,
Tilmann

Title: Re: Original Channel LED specs
Post by: amillar on January 23, 2025, 07:04:58 PM

Nothing special, just standard 3mm LEDs. We changed manufacturers several times as far as I remember.

The LEDs for the routing switches were hand selected for colour matching, but you would need to be very keen to do that!

Do you have any particular concerns about the specification?

Thanks,

Andy

Title: Re: Original Channel LED specs
Post by: tlmaen on January 24, 2025, 02:54:32 PM

Thanks Andy, I was more interested in the Voltage and Ampere rating...
So its standard 3v 20ma?

Thanks,
Tilmann

Title: Re: Original Channel LED specs
Post by: amillar on January 24, 2025, 07:37:44 PM

For current, yes standard LEDs that are labelled something like 20mA are what you want. What you don't want are LEDs that are labelled "low current" or "ultra brightness".

LEDs don't have a voltage rating, all red LEDs drop about 1.8V, all green and yellow / amber LEDs drop about 2V, it's set by physics. (In fact the 6000 desk there's a circuit in the 688 (the mix amp I think?) that uses this constant voltage property of LEDs.)  You can get "LED lamps" that are rated at, for example, 12V, but these are just assemblies of an LED and a resistor.

Here's an example of an LED that would work as a red LED, but there's loads of similar:
https://uk.farnell.com/multicomp-pro/mp006834/led-ultra-red-180mcd-637nm-t-1/dp/3648334

Hope that helps,

Andy


P.S. Here's a story about LED types. There was one special desk we made for a broadcaster where they wanted to use the routing matrix to create "mix minus" feeds - so they could have 31 of the 32 LEDs on at once. This would have overloaded the power supply and probably blown the 611 fuses, so I specified low current LEDs for this desk. Unfortunately I somehow forgot to change the resistor value on the production parts list - until one of the Sarahs in assembly came to me and said, totally seriously, "we like these high brightness LEDs"! I probably went as red as the LEDs...thank goodness Sarah happened to mention it, I don't think those LEDs (or the fuses) would have lasted long...