Exchange tips and tricks for the Akai MPC4000
By tenax Mon Jun 05, 2017 8:13 pm
Hi had the same issues (1st occurrence on hot days) I thought a reseating could help, but as I removed the LCD's ribbon from the mainboard a small piece of plastic (for stabilization) dropped off. I tried to fix but it was not so easy.
I found out some things about MPC4000 and this connector and I would like to share my experiences:

If you put the ribbon back to the connector it could happen that you produce a short circuit (by moving right or left). That failure leads to a non starting MPC (no fan running and noting else). Don't be afraid the main fuse works but there seems to be a fuse that heals up after a while (wait 5min). I removed the ribbon and after a while the MPC starts again (without display).

Reason is that a wrong connected ribbon for the LCD display can produce a short circuit in the 5V supply. But I found out to measure this SC at the power supply (P52 at the power board).

1 – red cable Pin = 5V
2 – gray = 5V
3 – gray = 5V
4 – GND
...
10 – gray = -15V

You can measure with a ohmmeter between Pin1 and Pin4 when the MPC is OFF. It should not be less than 30K. At my MPC it was round about 38K. If you measure this value you can sure enable you MPC4000 and maybe the display works. Sure you will measure this value also if the ribbon for the LCD is not in or only half connected but in the way I described you can avoid short circuits and stress for your power supply.

After a while I managed it to put the ribbon back without a SC and after I switched on my MPC the display works fine again.

Hope that help people with the same issue.