Hello from Italy (please pardon my poor english)
I’m the “technician” of an amateur rock band, and I’ve made a mistake during a live event, plugging the Yamaha MODX Left/mono output in the MIC input of the mixer, and then engaging the +48V Phantom power (which goes on all the channels).
The immediate result was an audible, periodic click (one every 2 seconds, more or less) from the MODX, and it took me about 10 minutes to realize the mistake.
Now, the problem is that the output seems … wrong. Some effects (like rotary, or some reverb) sounds weird, or with a different speed (the rotary going faster than before), while on the headphones everything sounds normal (i’m trusting the keyboard player, here, as i’m not familiar with the presets like he is). It all seems weird to me, but maybe the two channel are cross-talking now, or … i don’t really know.
We have other 3 events between the end of may and the first half of june, so bringing the synth to a Yamaha assistance is not an option until the last event.
BUT
i work in an electronic laboratory, and i wonder if it could be possible to get what’s wrong and maybe repair it, if the problem is in some component like condensers or … non-special parts.
So here i am, asking for any tip, suggestion, past experience, schematics or repair help: should i take a look inside the Synth? if yes, what should i look for? i have scopemeters (oscilloscopes? what’s the right name?) and good professional tools ar work, if needed.
Thanks
That is why you never plug live stuff into a desk without a DI in between (I use passive DI’s for keyboards, laptops, players etc etc) because you never know. (had a guy plug a laptop into a brand new A&H GL2400 - took the entire BUS out).
Anyway - does the headphone out sound strange as well (with nothing plugged into the line outs)?
Might not have done too much damage … worst case a couple of OPamps (BUT is all SMD)
Thank you!
Nope, the headphone out is perfect. Which makes sense …
… and which is why i wrote here, in hope of something like this.
But what seems really weird, to me, is -as example- a rotary effect going very fast (i mean: the preset shouldn’t have been intentionally programmed that way). As if some damage has done to the “logic” circuit … at my office i’ve seen any kind of weird effects when you loose one bit in a data bus, or some part of a RAM becomes unreadable, or unwriteable… and i really don’t know what are the chances of a damage like.
Yeah, i see. But we all are real amateurs: the instruments are personals, but the mixers, the loudspeakers, the monitors, the snake etc are bought by “the band”; them are six, each requiring gears, so the (tiny) amount of money they get from events still goes in “primary” things.
And plugging the keyboards in the Line inputs should be granted 
So - if headphones are fine then there’s is little left to look at (see below)
The FI301 and FI302 are noise suppressors … if suspect faulty could be bypassed with a bridge.
I would advise you to invest in a couple of passive DI’s to connect powered devices to the console (ie laptops and keyboards … etc) just to be on the save side.
They are not expensive and potentially save you a lot of money.
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Thank you so much, for both the repairing tips and the DI suggestion.
