MPC2000xl, noise in recording mode, input channel broken?

my brother bought a mpc2000xl, no 8out, no fxboard

...

in sample mode while recording i have a noise,
sounds like random short hissing sounds its quite loud.
it only appears when a input signal is turned on.
e.g. i put the need on a vinyl or start other sources.

tested with diffrent inputs, the rec and master output level doesent have any impact on the noise level.
i guess its not a ground loop problem, sounds diffrent.
removed the 16mb ram and tested with 2mb intern, same problem.

any ideas what to do next?

seems to me like the input channel has some analog problem ...

thx

greets gregsn

I know this may have been checked already, but have you tried different input cables? This is often over looked.

nope tested with diffrent cables

Do you have the record input connected with an amplifier output? If so try to plug the turntable output directly in to the record input. Worked for me!

are you even using a turntable preamp? usually you don't want the turntable directly into the mpc unless you are certain it outputs line level. a preamp converts a turntable to line level.
try a different source other than a turntable and see how it sounds. then you can rule out the input or the cables as being the problem.