Master fader output dead soundcraft sig12mtk

[DrewV]

Hi All. So, I noticed that the single master fader was outputting a little less on the left channel. Applying slight finger pressure (towards the left) on the fader seemed to temporarily correct it. I tried some heavier pressure and it started cutting out up and down the fader. Finally it made a brief grounding out type noise and died completely. I replaced the mfader but no signal is passing to the MF output jacks, Sub groups 1 & 2 work as does everything else on the board. The board is a Signature 12 MTK, 3 years old. Any ideas or suggestions greatly appreciated. Thanks

[The Dude]

Do you have a scope? If so, see if signal is getting in and/or out of the fader.
I haven't been inside one of these. Is it a double sided board with fader mounted on the board? If so and since the board kind of worked before repairs started, I'd suspect you may have broken a feed through when the fader was replaced. and signal isn't getting from one side of the board to the other.
Do you have a schematic? If so, please post it.

[DrewV]

Dude- alas, I have no scope. it is a double sided board with fader mounted on the board. 2 smaller boards are mounted directly above the output section - ribbon cabled. ( reset all) I can assign outputs of groups 1& 2 to the mf, still no mf output.. I would say the signal is getting to the output section as subgroups 1&2 , as well as aux outs all function. I re soldered all M fader conn to board... they look solid (maybe not?!) with the mf making a burst of noise , then going dead, is it possible I shorted something out? a resistor protecting an op amp? Working on getting a schem, soundcraft website is not responding well..ha

[The Dude]

Scope would be best, but if you don't have one, Use a DMM set to AC volts. Run a test tone into the unit and send to mains. Fader will likely be 1 outside pin ground, one outside pin signal input, wiper signal out. See if signal is getting to the fader. See if signal is coming out of the wiper pin. That should tell you if the problem is before or after fader. You might then have to follow traces to see where it goes from there if you can't get a schematic. Also check traces/pads where the fader solders in. If you broke a feedthrough, the bottom may look soldered, but traces on the topside may not be connected. You may have to also solder the topside pins if you can get to them.

[DrewV]

Alright, I'll take a closer look at the soldier points and traces, both sides of the board and then send a signal thru and see if I can determine where it's getting hung. will post follow up thanks

[DrewV]

Sorry for the delayed response...Too deep for me...had to give it up...Thanks for all the help.