Intermittant LR output problems Main outputs (XLR

These links may be of interest. https://www.soundonsound.com/forum/viewtopic.php?f=24&t=38329

http://forum.cakewalk.com/Help-ZED-R16-PLAYS-BACK-SOUND-ONLY-WITH-AFLPFL-PRESSED-m2342880.aspx

Several possible causes requiring further diagnostics.

Check the insert sockets.

Open it up. Look for blown or bulging capacitors.

Or

Take to Peavey Service

https://www.google.com/search?q=peavey+cs4000+service

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yes practically you can use, only make sure you balance the total output frequency

Make sure you are using BALANCED cables from this... eithe XLR or TRS cables. Using TS unbalnced cables MAY ground out the signal which is sent as balanced. Here is a schematic for the 24 channel unit... yours just has eight more channels. http://elektrotanya.com/behringer_ub2442fx-pro_sm.pdf/download.html
Scroll down to "get manual" and click to download. Ignore other download links.
By looking at the signal paths, you can OFTEN do a lot of testing from the available jacks. If the contacts on the right main INSERT jack go bad, that would cause your problem,,, NEVER use other than an insert cable in these jacks.

You need to connect the speakers using an XLR cable into the Main output jack on the back of the mixer. If they are powered speakers you will need to connect them into a power source and turn them on AFTER connecting them. Once powered on you can control the signal going to the mixer with the Main Mix fader.

1. Turn mixer on
2. Ensure Main Mix level is at zero
   
3. Connect from Main Output to Monitors
4. Turn Monitors on
5. Turn up Main mix to desired level
   

Personally I would run the RCA outputs to the RCA in on the APS.
If you insist on using XLR from the APS to the board (like through a snake etc) I would higly recommend using XLR to 1/4" adapters. These things have wonderful little transformers in them (yes, wire wound transformers) that do the 1/4" to XLR conversion really nicely so that you can run your signal through the snake or just so that you don't get the hum and distortion that can be associated with unbalanced signal transfer.
You want a HI-Z unbalanced to LO-Z balanced adapter.
Not always easy to find, but if you absolutely cannot locate any, I have a couple in stock.
I suggest you look around though, because mine aren't cheap!

There are a number of configurations for a mixer like the 1832, the most common are PA system and Recording system. There are Main output jacks which carry the mix as summed in the main faders. These in a PA system would feed the pa amplifiers which drive the house speaker system for the audience. These connectors are XLR 3 pin type on the rear, intended for professional pa amplifiers which use balanced +4dbv line input level. Amplifier which have 3 pin XLR connectors for input signals can accept that high level signal. For home style HiFi amplifiers, the signal level is nominally -10DBv and balanced or unbalanced signal lines with 1/4in diameter phone plugs which are connected to the mixer by way of a second set of Main output connectors which are 1/4in phone jacks. Use whichever amplifier input level your amp has.
If you are not using it as a main PA house mixer, but using it for recording, the main output connectors go to a 2 channel recorder or computer sound card recorder. The power amp and your monitor speakers are connected to the connectors labeled "Control Room" (CTRL Rm). These output are useful for recording because the signal through the mixer can be monitored from several buses, Solo, main mix, selected by buttons provided. The buttons only affect the signal heard through the control room monitors, and not the main output which only sees the main mix so selecting "solo" does not interrupt the signal going to the recorder while the engineer in the control can be checking other signal paths through the board.

Yes, there are chips in the unit and any COMPETENT tech should be able to repair.

Since both the XLR and the jack are bad, this implies something more.

USUALLY Mackie drives the XLR and the unbalanced jack seperately so the problem would be what drives the unbalanced jack.

CHECK if you have output at the UTILITY left output jack. If you do, the driver chip for the left output main is the problem.

If you don't, the problem may back up farther into the EQ.

A LOT of troubleshooting can be done on these by using the block diagram in your manual showing signal paths.

Ensoniq zr-76 no output signal on the main and aux, but i have output on headphone jack?