Yamaha MG16/6FX Mixer - intermittent channels - service manual?

[waspclothes]

Has anyone worked on this mixer (or similar) that has had a few intermittent channels? I'm hoping for a service manual or schematic.

When I say intermittent, I mean that occasionally they work and sometimes they don't... it seems like 3 channels are like this.

[The Dude]

https://elektrotanya.com/yamaha_mg16.../download.html

Usually dirty switches. Give the switches on the offending channels a good clean.

[g1]

Also, if it has insert jacks for the individual channels, clean them too.

[nickb]

https://elektrotanya.com/yamaha_mg16.../download.html

Usually dirty switches. Give the switches on the offending channels a good clean.

^^^^ This ^^^

Check the mute switches. Pop the button off and get some contact cleaner in there by putting the spray nozzle to the gap between the actuator and body. Then operate ten times or so.

[nevetslab]

Switch Cleaning

^^^^ This ^^^

Check the mute switches. Pop the button off and get some contact cleaner in there by putting the spray nozzle to the gap between the actuator and body. Then operate ten times or so.

You may find the mechanics of the switch, once the button is removed, will NOT allow contact cleaner to be injected into the body of the switch. Such is the case on this DPDT pushbutton switch I just removed from an old Harrison Console routing module. Complete with years of accumulation of dust and oxidation, to show what you're up against. In this particular instance, the back end of the switch happens to be open, instead of being completely sealed, which I'd bet is the case in your Yamaha mixer. And, as it's not discrete modules, allowing removal from the top, you'd have to open it up from the bottom and peer inside, to see if the switches ARE closed-back.



If indeed closed-back, and no spray-access from the front, you're left with what we all resort to.....feed LF tone into the affected channel, then either with your finger-tip, or an eraser end of a pencil, sit and exercise the switch until you hear the grunge go way and finally hear clean clear tone thru the channel again. Repeat this exercise with every switch that behaves that way. Old-switch-itis. Oxidation never sleeps. If you don't have LF tone available, pass music signal thru it.....just so you can hear if you're making progress or not. LF tone just happens to reveal the wide-band nastiness best. A studio maintenance technique. Over time, replacement of the switch becomes the solution, though shouldn't need that this soon.

[nickb]

You may find the mechanics of the switch, once the button is removed, will NOT allow contact cleaner to be injected into the body

You can do it with these if you do as I suggested, although t's not ideal. That said they sometimes are too far gone. Yamaha still have them as of a couple of months back.

[The Dude]

FWIW: I've had decent luck simply removing the switch cap and working the cleaner into the switch right at the actuator. Squirt as you move the switch in and out. No disassembly required. Use gravity and patience.

[waspclothes]

Thanks for all the suggestions everyone..

I did some tests showing that the problem was around the faders themselves. On a bad channel, I would get an output on an AUX if it was PRE-Fader, but no output if it was POST-Fader.

So I desoldered the fader, disassembled and cleaned. The wiper of the fader was completely covered in crapola, and once reassembled everything worked! So I soldered off every slider and gave it the same treatment and now the mixer is working great again.