Hissing noise problem with 2000 classic

So i recently bought an mpc 2000 classic. I have been having fun with it but there is one problem. Whenever i turn on the mpc it makes a continuous hissing noise. The noise becomes louder if i turn up the volume knob. I tried different speakers and headphones but that didnt work so i think the problem is in the mpc. The noise is coming from the left speaker, with headphone jack and also with speakers. I tried getting better cables, also didnt work. I am a total noob myself so i hope someone that has had experience with this problem can help, it would be apreciated Theres nothing wrong with the audio being recorded, the only problem is the hissing noise in the background. Sorry for bad english