Hello,

I have a Skytec PA-201 powered sound system for guitar and microphone. It has developed a problem that I need help with please. When I switch the PA on with mains connected, and turn up the main volume, there is a loud cyclical, pulsing audio noise at about 100 beats per minute. The battery status LEDs (3 green and 1 red) are all lit...but are pulsing at the same rate as the audio noise.The noise level increases as I turn up the main volume. If I then try to play a guitar through the PA, I hear pulsing echo sounds of the notes played.
I have left the PA connected to mains for 2-3 hours but, when I try use it using the internal battery, the LEDs are at about half the illumination level, there is no pulsing and I cannot play anything though the PA.

Any help will be apprecited.

I didn't find the right solution from the Internet.

References:
https://bit.ly/2mNBjc7
IT asset management service video

Thank you.