Yamaha MG24/14FX Faulty On Switches

[Don Allen]

I am looking at a Yamaha MG24/14FX mixer that has a fault with the channel ON switches. When you push the latching switches in, the channels come on as indicated by the amber light and audio present. When you deselect the latching button, there is a lag before the amber light goes out and audio cuts out. There are different delayed cutoff times for different channels. It appears to be a mechanical problem with the latching switches.

 

Has anyone come across this fault before ?

[sandall]

Has someone spilt their drink over the mixer, or tried to "clean" the switches with something unsuitable? If the latter a spray of IPA may do the trick; If the former it might be worth giving the PCB a wash with clean water.

[Hilary Watts]

I had a similar problem with a Samson mixer. I thought it was something to do with the latching mechanism or springs on the switches but it turned out to be simply friction between the push-on plastic 'knobs' on the switches and the cut outs in the metal chassis. The knobs didn't appear to be dirty or sticky but I removed them and cleaned them with IPA and it solved the problem. I didn't need to do anything to the latching mechanism or the switches themselves.

[Don Allen]

Thanks for the suggestion. Have had problems with lighting desk flash buttons sticking in the past, but not in this case.

 

These switch caps are free to move and captive with a lip under the metalwork. I have done more testing, the audio cuts out when the ON switch is deselected, even if the lamp stays on for a while. Other unused channel on switches lamp may flicker on when the switch cap is wiggled, not selected and no audio goes through into the busses. Will look into LED driver.