Low sound an hum from turntable with cobra tone arm 1955 wurlitzer but when another source is plugged in to aux in works fine. What could be causing this? Changed all the caps in this unit.

If you are experiencing an issue where the QSC RMX 1450 amplifier is not giving any sound when connected to the main output of your Mackie 16 OK mixer, but works when connected to the aux send, here are some possible causes and solutions:

1. Check the main output level on the Mackie mixer. If the level is too low or muted, this can cause the amplifier to not produce any sound. Increase the main output level on the mixer and check if the amplifier produces sound.
2. Check the cables connecting the mixer to the amplifier. If the cables are damaged or not connected properly, this can cause the amplifier to not produce any sound. Ensure that the cables are connected securely and are not damaged or broken.
3. Check the amplifier settings. Ensure that the amplifier is set to the correct input source and that the input gain level is set correctly. You may also want to check if there are any protection modes or limiters enabled on the amplifier.
4. Check the speaker connections. If the speakers are not connected properly or are damaged, this can cause the amplifier to not produce any sound. Ensure that the speakers are connected correctly and are not damaged.
5. If none of the above steps work, there may be an issue with the mixer or the amplifier. You may need to contact a qualified technician to further diagnose and repair the problem.

Remember to always follow the manufacturer's instructions and safety guidelines when working with audio equipmen

It was made between 1955 and 1960.

https://www.total-piano-care.com/wurlitzer-pianos.html

http://besbrodepianos.co.uk/pianoserialnumber/wurlitzer.htm

You have a bad ground somewhere. Try different cables and check the effect channel port if it is tight and secured.

Check to see if tone arm is in the correct position and did not get jostled out of place during the move.

Be sure needle did not get damaged.

Check to see if cartridge wires came loose during move.

Did turntable slip out of position?

Any cables come unplugged?

Any amplifier fuses blown or mechanism power supply fuses blown?

Your gonna have to open it up, Tighten her up.

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.

spray some contact cleaner in the head phone jack and plug and unplug a headphone in a few times. It should clean it up to play.

gapoko

I suspect the power supply has an issue. Most likely bad filter capacitors. This could cause "motorboating" where power is drawn and supply voltage collapses and then recovers repeatedly.

Time for the repair shop. The parts cost should be nominal... labor... well...

The preamp section has a problem. It could be anything in the preamp but is OFTEN the input jack itself. They take a lot of abuse.

Also the insert jack contacts that forward the preamp to the power amp if no external FX are used can go bad.

Additional things are circuit board cracks caused by rough handling and also controls that have had the knobs mashed in which can destroy the potentiometers they are connected to.