M312 light replacement issues!

[Zachary sterman]

I successfully replaced all the lights in my M312 with blue LED's because I'm a nerd! figured it would be easy, and it turned out to be a simple process with great help from the holy internet.

BUT when I switched on the power for that VOILA! moment, only every other light seems to be working; obviously they are brand new lights. I wonder if anyone has any clues as to where I should look, or if you have experienced this before. I bought the console with the lights not working, so not sure the history there. any tips??? would love to have these meters lighting up my mixes! (LOL)

 

[SkywaveTDR]

I would put the correct lamps in the mixer as LED make products look cheap and silly unless a great deal of trouble is gone to control the brightness and the color to be like lamps.
I can already tell that I would be annoyed by that meter color if I had to use it all day long. Most every deck I have seen with LED's in them looked far too bright and upsetting to the eye- they all have been done wrong.

 

[Zachary sterman]

You always hate on me SkywaveTDR. I’m just lookin for some help:/

 

[wkrbee]

Did you wire the LEDS correctly? They are polarized.

 

[Zachary sterman]

These are the specs for the LED

Wavelength: 470nm Max Reverse Voltage: 5V
Luminous Intensity: 9,300mcd typ. @ 20mA Power Dissipation: 120mW
Max Forward Current: 30mA Operating Temp: -30 to +85 C
Pulse Current: 100mA for <= 10ms, duty <= 1/10 Soldering Temp: 265 C for 10 secs
Forward Voltage: 3.2V typ. 3.5V max @ 20mA Max Reverse Current: 50uA @ 5V

I then attached a 220 ohm resistor on the positive side of each led and lightly soldered them where the previous lights were.

See any obvious issues? I’m stumped

 

[Zachary sterman]

Welp. I plugged it in and the whole board passes zero audio. No output gives me anything, master, D outs, nothing. The headphone jack gives me its usual noise. That’s it. I guess this is what happens when I want to try and fix my stuff. Thanks for the help anyways. I’ll have to look into buying a new one.

 

[SkywaveTDR]

I hate on no one. The comment is directed towards the use of the wrong product in trying to fix something- I am trying to help you by telling you NOT to use abstract parts.
I have had clients or people that I help use car lamps in the 34 tape deck meters- these draw 250mA instead of 55mA which is the lamp they are suppose to use. The problem is that too much current draw can collapse the meter lamp power supply. You might say what does that matter? Well in the tape deck case the meter lamp circuit also is the supply detection for the power mute circuit- use the wrong lamps and the supply never comes up enough to release the power mute circuit and then no audio. I have not looked at the mixer circuit but you may need to see if the power mute circuit is working or defective or if the LED's are drawing too much current.
I would rectify into DC the supply, Filter with a capacitor, then feed that into a proto board with a LM317 regulator on it with a Cermet trimmer on it. Then all LED's could be set from that supply with the pot for the right brightness and honestly Blue LED color is obnoxious. Get Amber or Yellow as is used on Panasonic Ramsa or even on Yamaha or Crest Boards. These companies have used LED's in their mixer meters effectively. And they could be used for a lot of hours without eye fatigue.