Yamaha EMX512sc main out LEDs not working

[BluesCam]

Hello everyone. I purchased a used Yamaha EMX512 and everything works fine, except the main LEDs do not light up at all. The monitor Leds work fine. There are LED drivers for Left and Right main outputs. Any ideas? Thanks!

[The Dude]

Schematic Link:

YAMAHA EMX512SC-EMX312SC Service Manual free download, schematics, eeprom, repair info for electronics

[BluesCam]

Schematic Link:

YAMAHA EMX512SC-EMX312SC Service Manual free download, schematics, eeprom, repair info for electronics

Thanks for the link!

[oc disorder]

Here's a simplified section of the schematic and the board.
I guess I'd start by checking for the supply there at pin 9 , 12 volts
and then check for some audio signal at pin 8 of the LED driver IC the LB1423N.
Careful of the switchmode supply it's live and dangerous ... you may have to connect the
front foil to the one in the case .. I recall some discussion about the supply.
It wouldn't start up unless the foils are connected.
You could also compare readings with the "good one" the monitor led VU. as that may give some clues.






Here's a link to the grounding info JP Bass made from a post by 1984ARC should you require it.
http://music-electronics-forum.com/a...o-emx512sc.pdf

[BluesCam]

Thank you very much! Very helpful!

Here's a simplified section of the schematic and the board.
I guess I'd start by checking for the supply there at pin 9 , 12 volts
and then check for some audio signal at pin 8 of the LED driver IC the LB1423N.
Careful of the switchmode supply it's live and dangerous ... you may have to connect the
front foil to the one in the case .. I recall some discussion about the supply.
It wouldn't start up unless the foils are connected.
You could also compare readings with the "good one" the monitor led VU. as that may give some clues.



[ATTACH=CONFIG]37172[/ATTACH][ATTACH=CONFIG]37173[/ATTACH]


Here's a link to the grounding info JP Bass made from a post by 1984ARC should you require it.
http://music-electronics-forum.com/a...o-emx512sc.pdf