[sdiy] korg poly6 leds

[Tom Wiltshire]

Hi Nate,

On 17 Mar 2009, at 21:05, Nate Reeves wrote:

> seeing the poly 6 on ebay with new bright leds got me inspired to  
> do the same with my unit...
>
> what should i look for when stuffing the replacements?

You'll need to watch out for the current rating, so you don't put in  
new LEDs that use more juice than the old ones and fry something.
There are a few others, but most of the LEDs are on the KLM371 panel  
board, and are driven by  SN74LS75 four bit latches. The LEDs are  
hanging off the +5V rail with a 470R resistor, so the chip is sinking  
current rather than sourcing it. You can look up in the datasheet how  
much the outputs on this chip can take. If you're adding new  
superbright LEDs, you may well need to replace the resistors too to  
limit the current to a safe level.
Even with increased resistance, I'd still expect them to be much  
brighter. LED efficiency has improved a lot since the polysix was built.

> i got some Superbright LEDS but one leg is longer than the other....
>
> does it matter which way i drop in the new led?

Yes. LEDs are like all diodes and need to be the right way around.  
Test one of your LEDs first to find out which round it should be and  
how much current it draws with a 470R resistor.

> doesnt seem like the list is running as of late....

No, it definitely disappeared for a bit there.

T.