Mixers/Consoles Channel Loses Signal on Mackie Sound Board

[jlepp06]

So, here's my thing... and I'm bringing it here as I couldn't find much on google.

I have a sound board that randomly will lose signal in a couple channels.
I don't remember the exact model, but I know it's a larger Mackie board.
The channels do not all go out at once, but I know it's a few of the same channels that do it.
Everything will be working fine, then you will lose signal completely until you unplug then plug back in the XLR cable into the back of the board, then voila!, it works again.
It doesn't matter if it is phantom powered equipment or not.

Again, it's only that specific channel that will lose signal, not the whole board, other channels continue to operate correctly.

 

[chausman]

Sounds like a loose ribbon cable or the like.

 

[FMEng]

It could be a dirty XLR connector. More likely, it is a dirty insert jack. Spray the jacks with Caig DeoxIT D5, then immediately exercise them by plugging/unplugging into them many times. Finish by applying Caig DeoxIT Gold G5. The D5 is a cleaner, the G5 is a preservative.

The insert jack has contacts have to complete the audio circuit from the preamp to the next stage, when nothing is plugged in. Oxidation forms on those contacts causes them to become intermittent. This is a common problem for almost any console with inserts, especially as they get older.

If it proves not to be the XLR or insert, there are numerous small ribbon cables inside the console, but those are less likely to be the culprit. Always try the easiest, most likely stuff first.

Radio Shack sells a package with both sprays for $20, Cat #64-4338. Spendy for a small quantity, but more convenient than mail ordering. Those two products should be in the tool box of anyone who deals with electronics. By far, the most common problem I encounter is dirty contacts on switches and connectors.

 

[jlepp06]

Thanks for the responses.
I'll take a look and see what I can find out.
It would be nice if it were something simple like dirty contacts.

 

[philwantspro6]

Great thought on insert jacks. I would say before spending money, just exercise the plugs by going down the line and plugging quarter inch into the jacks a few times on the channels that have open insert jacks.