MPC4000 cleaning, repair and improvements

it's because the led are much brighter than the CCFL bulb

You should sell actual kits for this. I believe it is the same screen and driver board for the Akai S5000 and S6000 series samplers as well.

perhaps but I must find a service manual for the S5000/6000 to be sure

Count me in on a light for the 4000 display. Could you make the light dim able?

at the moment you are the only one interested xD
it's dimmable you can see the pot on some pictures. but it needs to drill a hole if you want to have access to it from the outside.

You did a great job with this. Im an electrian so I can follow most of this but I sort of lost you after you made the led strip. You had to replace what I interpret to be the "ballast" correct? And created a chip that would provide you with the propper amps / voltage for the led strip?

Genesis92 wrote:at the moment you are the only one interested xD
it's dimmable you can see the pot on some pictures. but it needs to drill a hole if you want to have access to it from the outside.

Thanks.

Wow man you really have to get into MPC repairs and stuff. There is no one in Europe, I could hapilly be one of your clients!

thanks
but I'm not a professional, it's only for hobbying and to help others who will need informations to make the same thing on their systems.

I will try to quote the led assembly PCB + led power supply PCBs if some guys are interested to upgrade their CFL backlight but it requires some skills to remove the old CFL one.

I used the exact model/brand of leds that Genesis used in this project and was nearly blinded by how bright they were. It was to the point I could not look at my machine.

So I had to put 4 layers of ice scotch tape over the shielding plate just to diffuse it to the point of being usable again lol.

Strange because it's ok for me. But another solution could be to increase the value of the led current limiting resistors R200 to R204 and give less current to the leds.

Genesis I was actually going to look into that but I've been lazy during the Christmas holidays. Thanks for the reminder though. Btw, I put the leds in the 2K XL. I'll have to verify the resistor values.

ah ok, not in the 4K, perhaps the 2K XL give more current to the led or use a lower scan frequency.
but yes I have choosen high intensity/efficiency leds because it's easier to lower the current after than to get a lack of luminous power

@Genesis - with the 4000, am I right when I believe the R200-R201 are using 270ohm resistor and R02-R204 are using 75ohm?, all powered at 5v?

yes
it's because there's more leds in some strands and with another color.
the voltage drop in a led is differnt according to colors.
so to have slightly the same current in the strands with more leds in serie you must have a lower limiting resistor value.

It's not a critical value and check wich led are too powerfull.
Check their ID on the board/schematic and in wich strand they are.
So when you know on wich resistor they are connected, increase it's value to decrease the current in the led.

The rule is to never go under 50 ohms to avoid to kill the leds. In the other way there's no limit and you can go up to 10K ohms without problem (I already used such value with high intensity / efficiency leds).

If you have some electronic skill you can add a 10K potentiometer in serie with the resistor (be aware to keep the resistor in serie) and you turn the potentiometer to reach your "visual value". when it's done, carefullu disconnect the potentiometer and measure it's value.
add this value to the serie resistance and replace the whole value by the nearest E12/E24 serie 1/4W resistor