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Adding high brightness LED's...problem!

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crunchy

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Hi Guys, newbie, but a tinkerer nonetheless..
Trying to add hi bright leds to my ART X-15 MIDI foot controller, and garbled signals/voltages everywhere...
here's the schematic link...

{https://www.electro-tech-online.com/custompdfs/2007/02/X-15_Schematic.pdf }

Sucessfully added them to my X-11 controller a while ago w/no probs...
This one seems to have a different LED array, and I know I probably need to swap out (or Parallel) resistors to get the right voltage to them...

However, the schem is confusing (to me anyway!) as far as the forward current goes...it looks to me as if the transistors supply the voltage directly to the leds... the resistor array near the top of the schem seem to come after the led..
I hate being a newbie, I've done so many hack mods, one day I'll actually learn what I'm doing...

Any quick expert help would be great, this is very very urgent!
Thx heaps guys..
 
Last edited:
crunchy said:
Hi Guys, newbie, but a tinkerer nonetheless..
Trying to add hi bright leds to my ART X-15 MIDI foot controller, and garbled signals/voltages everywhere...
here's the schematic link...

https://www.electro-tech-online.com/custompdfs/2007/02/X-15_Schematic-1.pdf

Sucessfully added them to my X-11 controller a while ago w/no probs...
This one seems to have a different LED array, and I know I probably need to swap out (or Parallel) resistors to get the right voltage to them...

However, the schem is confusing (to me anyway!) as far as the forward current goes...it looks to me as if the transistors supply the voltage directly to the leds... the resistor array near the top of the schem seem to come after the led..
I hate being a newbie, I've done so many hack mods, one day I'll actually learn what I'm doing...

Any quick expert help would be great, this is very very urgent!
Thx heaps guys..

The LEDs are sourced by the transistors through the resistors and sunk through U9. If you are changing to one of the new green or blue LEDs you will probably have a problem since they run at ~3.5V instead of ~2V.

D.
 
some more info from the site:

"This is the main PCB where the 74HC244 chips can be found and are labeled U6 & U9. U1 is a EPROM chip, U2 is a SOIC Octal "D Latch", U3 is an 8-bit microcontroller, U4 is a standard logic IC, U5 is a serial access EEPROM chip, U7 is a logic gate and U8 is an photocoupler."

any help? can I change U9 to something else to allow the right voltage through?

Am I stuffed, or is there a difficult solution, I'm willing to try it!

There is about $60 worth of leds that I'll have to destroy if replacing with normal leds... long story, but unavoidable really.
 
crunchy said:
some more info from the site:

"This is the main PCB where the 74HC244 chips can be found and are labeled U6 & U9. U1 is a EPROM chip, U2 is a SOIC Octal "D Latch", U3 is an 8-bit microcontroller, U4 is a standard logic IC, U5 is a serial access EEPROM chip, U7 is a logic gate and U8 is an photocoupler."

any help? can I change U9 to something else to allow the right voltage through?

Am I stuffed, or is there a difficult solution, I'm willing to try it!

There is about $60 worth of leds that I'll have to destroy if replacing with normal leds... long story, but unavoidable really.

break out the blues and whites and give them their own resistors back to U9 with say a 50:eek:hm: and see what the drop across the 50 is. If it is only 0.5V change it to 25:eek:hm:

D.
 
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