I have gps 900 peavey the problem is motorboating sounds,can you help me please

You can get the best answer from Peavey directly. here's their link-
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If you decide to send itto them for service, here's that info-
Peavey com

Hi

It sounds like your circuit board may have a bad solder joint. Sometimes during manufacture of the ciruit board, the joint could not be perfectly made. This will limit conduction and create heat which will worsen the effect over time. If you are familiar with opening and working with electronics then I suggest you remove the circuit board and inspect it for cold solder joints. When you find one, you can use a Cigar Torch type lighter to help reflow the solder easily. Out side of that, you mayu want to send it to a Electronics repair shop to do this for you. Let me know more and I will help. Good luck

'Motorboating' is an oscillation caused by positive feedback - usually due to poor decoupling around the amplifier stages. This can be caused by dried out electrolytic capacitors, so check for 'domed' tops on these. Turn Master Gain controls to zero - if the motorboating persists,then the problem is in the output stages - this is an important test to do.
You need to give more information eg
i) does this fault occur at all volume levels?
ii) is it on all channels?
iii) does it happen immediately at switchon?

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

The amp is doing what is called "motorboating". This is usually caused when the voltages to sensitive preamp stages are inadequately filtered or regulated and the sudden load of the output stages cause a dip in the voltages sent to the preamps which in turn vary the input to the output stages starting the cycle over. This will require electronic troubleshooting and if your not skilled in that, then it is NOT a DIY fix. What you are seeing is NOT normal, there is a defect.

You will need to remove either the top or bottom panel to get at the jacks. There is probably a bad solder joint that needs to be repaired. You might try tightening the screws on the XLR jacks that fasten them to the back panel first and the nuts that fasten the 1/4"jacks also. I really do not recommend you do this yourself ( accessing the interior) unless you have electronic servicing experience as the filter capacitors in the power supply store a dangerous charge and are soldered to the circuit board in fairly close vicinity to the output stage.

You CANNOT link the outputs of the amps. They need to drive seperate speakers.

You can tie the inputs together so they will send the same sound to their seperate speakers.

Max power for the Peavey 900 is 900 Watts RMS into a 4 ohm speaker in Bridge mode... That is enough to blow many speakers.

Sanyo tech service helped.

The problem you have mentioned is a common one with old sets, but it also occurs in new ones also, though not frequent. You can fix this just by changing the electrolytic filter capacitors in the power supply and sub filters on the amp PCB. The new capacitors should be of the same or higher voltage rating and same capacity rating as of the existing ones. And as it is such an old one, it is better to change all the electrolytic capacitors to avoid any further problems.