MPC 3000 buttons, data wheel and pads problem

Definitly not the midi cable, cause it starts the other device just fine.

sbtst6 wrote:Definitly not the midi cable, cause it starts the other device just fine.

not the MIDI cable, dear. the ribbon.

Did you allready found a solution for this problem???

i ve got the same problem and could not solve it so far. does anyone have a solution for this?

EDIT :

I just measured the Power Supply and recognized that PIN 6 of the Connector P1( W904) which should be 5 V is around 7-8 V and is fluctuating with an amplitude of 1V in a Sawtooth like manner...

This Pin is connected directly to the output of the Recitifier and to the input of the 5V Regulator so i wonder why the service manual says it should be 5 V.

Random failures and power issues can sometimes be attributed to failing/dry/leaking capacitors in the power supply. Replace the electrolytic in the power supply if they have not been replaced in the past 10 years. The service manual has the list of parts you need; if you can find capacitors rated at 105C, use these instead of the 85C ones as they are supposed to be more robust to thermal issues.

okay ill try that.

I also forgot to say that the machine will work after a while being on in that state which also supports the assumption that is has something to do with capacitors.

Perhaps a capacitor is leaking and if it is loaded faster then it leaks when the machine is on.
So when i restart the machine after a while when the capacitor is loaded enough its somekind of preloaded for the boot process or sth...

anyways, i cannot see any signs of old/damaged capacitors on the Power Supply board and if i measure the power pins when the machine is on and power is connected everything seems normal except the voltage on pin 6 from Connector P1, which is not +5 V as I described before. But this behaviour seems logical concerning the circuit.. because this pin is connected directly before the regulator and after the recitifier.

I hope i can somehow fix the machine and start having fun making music = )

if somebody has some more tips and hints please help me

best wishes,
flo

Try changing the capacitors first and see if it corrects the issue. The purpose of the capacitors are to remove noise and ripple off the power lines. Noise and digital circuits do not get along. The capacitors may not look bulged or damaged, but I imagine at this point in their long life the chemicals inside are dry and ineffective.

At pin 6 you are measuring the unregulated 5V line. It is shown on the schematic as 5U. Depending on the load when you are measuring, there will be some variance in the readings since it is unregulated. So this sounds normal.

Please report back and share with others your results when you have them.

Okay,
I changed almost every capacitor on the power supply board.

The Problem still occurs on cold bott after a while it works just normal.

mh could it be the OS eproms?

Has anyone an idea what this could be?

I measured the power line when the problem was active ( only 3-5 minutes after cold starting the mpc, after this time it works just fine)
everything seems to be ok.

I know this is an old post, but I'm very interested to know if you finally found a solution to the problem of the frozen buttons after booting. I have exactly the same probelm, with only PAD bank A led on. The cursor blinking on the Main creen, but no buttons responding.
Please, any help would be greatly appreciated. Thanks

Carlos