Allen and Heath PA 28 is making pulsating sound, lights blink for left and right channels and the sound can be heard throught speakers. It won't go away and it is impossible to use the mixing board. What is causing this problem and how do I fix it?

Check the insert sockets.

If one of the channels on your Allen & Heath XONE:42 mixer is not functioning properly, it is likely due to a problem with the channel's internal components or electronics. To repair a blown left channel, you will need to disassemble the mixer and locate the source of the problem.

Here are the general steps you can follow to troubleshoot and repair a blown channel on your Allen & Heath XONE:42 mixer:

Disconnect the mixer from any power sources and remove any cables or accessories that are connected to it.

Carefully disassemble the mixer, following the instructions in the user manual or a service manual if available.

Once you have access to the internal components of the mixer, carefully inspect the left channel for any visible damage or problems.

If you find any damaged or faulty components, you will need to replace them. You may be able to find replacement parts online or through a specialist DJ equipment retailer.

If you are not comfortable with disassembling and repairing the mixer yourself, you may want to consider taking it to a professional repair service. A technician will be able to diagnose the problem and repair the mixer for you.

Keep in mind that repairing electronic equipment can be complex and requires specialized knowledge and tools. If you are not familiar with electronics repair, it is recommended to seek the assistance of a professional.

Hello,

Carbon track on fader 1 is open because of wear or just broken, if you are getting sound then the ground carbon track is out but certainly the problem lies in the pot.

Auxiliary output sockets (AUX 1-6) would usually be used for connecting to an FX unit input, with the signal levels sent to the FX unit governed by the AUX SEND pots from each input channel, setting the AUX MASTER at a level that will prevent peak signals from the various channels (sent to the FX unit) from clipping the AUX bus rails.
The output of your FX unit can be then be returned to stereo line input sockets (ST1-4).
For details see the GL2400 User Guide:
AUX OUT 1-6 (p.15),
AUX SENDS (p.17/18),
AUX MASTERS (p.19),
STEREO CHANNEL LINE IN (p.14).
If you require more precise EQ parameter control of FX return signals - and you have sufficient spare channels on the desk, connect to 2 x mono channel inputs:
one from left FX return, one from right FX return, with each of the console's input channels panned hard-left/hard-right (this assumes the FX unit has a stereo return).

If you are experiencing a mid-range humming from your monitors when using your Allen & Heath PA12-CP mixer, there may be a problem with the signal level or the cables.
Here are a few steps you can try to troubleshoot and resolve this issue:

1. Check the signal level of the sources that are being sent to the monitors (e.g. kick drum, snare, etc.). Make sure they are not too loud or too quiet, as this can cause the limiter to engage and create a humming sound.
2. Check the cables that are connected to the monitors. Make sure they are not damaged or loose, and that they are properly connected to the mixer and the monitors.
3. Try using a different set of monitors to see if the problem persists. If the humming is still present, the problem may be with the mixer itself.
4. If you are still experiencing a humming sound, you may need to contact Allen & Heath customer support for assistance. They will be able to provide you with more detailed troubleshooting steps and help you resolve the issue.

Overall, if you are experiencing a humming sound from your monitors when using your Allen & Heath PA12-CP mixer, the problem may be with the signal level, the cables, or the mixer itself. Follow the steps above to troubleshoot and resolve the issue.

Does the left meter do the same thing? If the meter matches the right one, I would suspect the volume potentiometer on the powered speaker. Try exercising the volume knob. There might be some oxidizing on the potentiometer.

Cases are being sold on Ebay, new, from several sources, and if you can't find one specifically listed for your unit, contact the sellers as they custom build them. That is a big unit... expect to pay around $150 to $200 for an ATA type case for it.

Here is an example for a Heath/Allen 420. http://cgi.ebay.com/ATA-CASE-ALLEN-HEATH-ZED-420-ZED-420-ZED420-MIXER-/400127078772?pt=LH_DefaultDomain_0&hash=item5d296eb174

I have bought from them before myself and there are others on Ebay so shop around... You can contact the companies and ask for a specific one and DO compare the size to your unit that they specify as all the companies do not accept returns...

Run the RCA cables into TWO channels of the mixer. PAN those two in opposite directions to create stereo signals inti and out of the mixer.

Is this for live sound? You can use your aux outputs as sends if you're not using them for monitors and return to spare channels. If any units are being used for only one channel, either run them in-line (use the effect unit's wet/dry settings) or use the channel's direct out and return to a spare channel.

If one effect is applied to several channels you could put those into a sub group, take that sub output to the unit and return the 100% wet mix to a spare channel.

Be careful not to send the return channels back to any auxiliaries you're using for effects.

There can be any number of reasons for this problem - solve it diagnostically by starting with something that you know is working and work through systematically to the other end.

1. Test a microphone on a separate amp to make sure it works okay. Check amp and speakers working. Check that all output cables from mixer to amp are working by testing separately.
2. Plug microphone into a channel on mixer. Also plug in headphones and turn headphone volume control up.
3. Make sure input sensitivity knob is turned up a bit (say half way) and main output faders (yellow) are up.
4. Check that channel is turned on (little button just above the channel fader- needs to be pressed down)
5. press pfl (pre-fade listen) button (next to button to switch channel on)- do you get any sound on main output or headphones or any indicator lights on mixer to show signal is getting that far (eitehr the individual channel metering lights or the main ones in the central section)?
6. turn off pfl - make sure channel fader (slider) is up - normal position is ) - about 3/4 of way up. Check lights again on individual channel and main output section - any signs?
7. Is the sub mix button for the channel pressed down - in which case you will need to bring sub mix (red) output faders up as well as main faders.
8. If you have got signs of signal on the individual channel but not main see if the channel has been routed somewhere odd (like a subgroup of channels).
9. Plug a working amp and speakers into one of the auxiliary outputs and use the relevant auxiliary send knob (on each channel just above the faders and pfl switches) to pan some signal to that auxiliary out - do you get anything? There is also a headphone socket for listening to the auxiliary channels (with a selector switch /knob to determine which one - make sure it is in the right position) try listening to the auxiliary output with headphones - anything? If yes the problem lies in the main output section.
10. Check that there is not a jack plug in the insert socket (to route signal through an external effects unit) without a matching return jack being plugged in - if appropriate is relevant effects unit switched on and correctly set up - if unsure remove the insert plug to take it out of the system.
11. Make sure any mute buttons are not switched in on main outputs.

You can download a full user manual here http://www.allen-heath.com/gl/gl2400