Some channels stop working

The flashing green light on your Behringer Pmp500 mixer desk indicates that it's receiving a signal, but it's unclear why the first 4 channels aren't working. Make sure that all cables and connections are properly secured and that the power supply is adequate for the mixer's needs. If the issue persists, you may need to consult a professional for further troubleshooting or repair.

Work ALL switches and controls, if a switch or control sits doing nothing for long periods of time they will become resistive if not open. Just work every one and see if that doesn't fix it.

Sherman, you are answering a question from 2014! Everything on Fixya is FREE.

https://www.google.com/search?q=Schematic+for+rms+pm8200r+8+channel+mixer

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the pa1 or the pa2 input jack on the front of the unit is dirty, or you have a cracked solder somewhere, as these units are gettting old.

Look for a 'monitor' switch, change it's position.

Where do you have the gain control set on the Mic channel ?
If you have no issues with either the speakers or the Mic, and the gain control for the channel you have the Mic plugged into is set at a somewhat "normal" position, you might have a problem with the mixer itself.

The PMP has an electronic overload protection. If you overload one or the other of the outputs, it trips the protector and you have to cycle the power off for a bit to reset it. You haven't mentioned what speakers you have. Be aware that the impedance can be no lower than 4 ohms on either channel. In addition, I have seen some particular speakers that have transformer attentuators in them that this amp is NOT happy driving. You could not attach more than two 8 ohm speakers to each of the outputs without tripping the protector.

You can do it one of two ways when coupled with the FCA202. First, You can just come out of the main outs on the 802 via 1/4 in to the 202s 1/L in and 2/R in. Second, you could do two separate channels (ie. Vocal channel and Guitar Channel) using the L/R out on the 802. Use the pan knob to send the instrument to the selected channel. So, If your Guitar is on channel 1 pan hard left and you will only get it out of the left channel sending to channel 1 of the 202, and your vocal is in channel 2 pan hard right and you will only get it out of the left channel sending to channel 2 on the 202. Good Luck, Cody J.

Try performing a full firmware re-install, or update if your not already on the current firmware. Click on the "Downloads" tab to access the latest firmware. http://www.peavey.com/products/browse.cfm/action/detail/item/116194/32FX™.cfm

Probably a blown opamp