Noise & High pitched sound when sampling

When i go into sample mode, the mpc 3000 starts making noise and even adds it on my samples, if i set the record level a bit lower, the noise is still there but a bit lower. its comming from stereo out and mono outputs and wont dissapear. anyone know whats the problem? i uploaded a sample of this annoying thing here:

http://www2.zippyshare.com/v/5167379/file.html

any suggestions?

Yes its a simple fix.

Its either the power supply or the inverter.

The power source is easy to spot, the inverter is a smaller piece on the right side with two small wires hooked to it. One is from the power supply the other one goes to the screen area.

Much likely that the boise is from the inverter. You can test it. Unplug the mpc, remove the power lead make sure you are not charged with any kind of electricity, open it and unplug the two wires from the inverter. Once everything is put back together safely go to sample mode and and check whether the noise is gone. You'll take it from there

Could you test whether the inverter is whining by turning the backlight on and off with the backlight on/off switch?

The inverter noise will only find its wsy into the audio line 2 ways.

1. (Most Common) the el foil (backlight) feed wire is not tied down correctly and is too close to the gain trim pot wires. This fault is common after a home backlight change and just making sure the wires dont touch is all it takes

2. (Much less likely) the inverter has become ungrounded, if the ground line for the inverter is split, the hum will make irs way to the audio line.

Step one, turn backlight off... if the hum stops, open and check 1.

If you dont understand judt take a picture of the open unit and I am sure you will need little effort to put it right

i changed the backlight foil a while ago because the screen was not working, im sure everything is right but it seems like the inverter is dead( no backlight ) i will check it again and reply soon BTW do anyone know where i can buy a new one? just wondering but ill check it with multimeter first. how much voltage should it be there 4-5?

It is a few volts DC (5?) going into the inverter from the power supply, and a couple of hundred volts AC coming out of the inverter and into the backlight.

Did the replacement backlight work after you installed it?

Does pushing down on the display contrast knob, which doubles as a backlight on/off switch, make any difference?

Nope it was still dead, i havent checked anything more just changed the backlight foil. Tried the on/off button too, still not working. should i look closer on the inventer?

It's strange to have that interference with an inverter that doesn't work.

As Simon said, checking voltages is a good plan, but its not very easy to check the Dc in on the inverter as its fixed out of reach, check the output first and that's the ac one.

If you are really stuck and in the uk, you can click the link below my message for some more info

Also, check foil power socket (2pin) on inverter out is not damaged

Please be VERY CAREFUL when poking around inside a powered up MPC!!!

The inverter is very close to live mains/AC power, touch the wrong bit and you could kill yourself.

This happened to me too. I get this high pitch fizz. Basically, I just had to make sure that all other levels on my mixer was turned down, except the track I was playing the sample through.

Let me know if that works.

I don't know the exact issue, but if I had to guess, I assume it's some sort of sound leak + feedback loop.

Im back again. i soldered the inverter board and now the inverter is working( but when its on for a while it starts whining, i guess its old and need to be replaced), i grounded my CF Reader to main board and the main high pitched noise disappeared. (most annoying) But i still have the aliasing noise when i set the record level to max but.. i checked out my sampling cable and the jack in it looks bad..it seems that the problem is right there, i spinned it around = quietly noise, spinned it again = no noise at all but now its back, i will order new cables and post the results.