MPC 4000 screen not working vertical lines.

So I replaced both my MPC 4000 display (TWICE!) and the FPC cable attached to the display PCB and the I/O PCB and there are still vertical lines on the screen. What could this mean? is the display PCB faulty? Is the port where you attach the FPC cable to the I/O board faulty? I am at a loss here. It can't be the display itself because I have replaced it twice and the lines are exactly the same and It can't be the cable because nothing changed when I replaced it.

I have attached a link to an image of what my screen looks like. The majority of the time, the text is difficult to read which is why I want to fix the problem.

https://ibb.co/QLRRdF7
https://ibb.co/V0rQPpMR
https://ibb.co/RkdFZRvx
https://ibb.co/v4zgCWnG
https://ibb.co/dwm86zDQ
https://ibb.co/8gF7WQ6K

As you replaced both screen and cable the main suspect is the mainboard connector.
Inspect the ends of the cable(s) with a good magnifier if the lead ink is damaged (unlikely, though).

Dirt inside the connector (essentially impossible to visually detect) might prevent a solid connection.
A very thin piece of stiff cardboard or plastic (sand it for a rough surface) as a kind of brush (push in and out a couple of times) may help.

The regular pattern of the lines could point to video Ram, so remove/insert Memory is worth a try.
Some error on video clock could have a similar effect, though...

best of luck, Tom

I attempted to clean the mainboard connector with an air duster and a piece of paper and I also attempted reseating the flat flex cable and the ram, but neither of those solved the issue. So my next idea is soldering a new flat flex cable socket to the mainboard. Since the flat flex cable is a 1.25 mm pitch with 14 pins, I think I'll buy the part from here:

https://www.aliexpress.us/item/32568014 ... 4itemAdapt

I‘d rather check the display controller/timing before replacing the ribbon connector.
I gave a wrong hint above about display memory, which is NOT part of the MPC memory, but located on the display controller itself, sorry.

Details about the display can be found in
LIQUID CRYSTAL DISPLAY MODULE G321EV USER'S MANUAL
( a link to this unit was posted here sometime ago)

Telefunky wrote:I‘d rather check the display controller/timing before replacing the ribbon connector.
I gave a wrong hint above about display memory, which is NOT part of the MPC memory, but located on the display controller itself, sorry.

Details about the display can be found in
LIQUID CRYSTAL DISPLAY MODULE G321EV USER'S MANUAL
( a link to this unit was posted here sometime ago)

Is this what you're talking about?: https://manualzz.com/doc/6952432/seiko- ... e_vignette

What should I be looking for in this manual?

the PDF manual of the G321ev just explains parts and function from page 9 to 18.
But you already replaced both screen and cable and it didn‘t change the result, so it‘s unlikely the display is faulty.

In MPC Service Manual the bottom left section of the PC IO Block Diagram points to the display connection. Inspect that part of the hardware, in particular in regard to timing.

It‘s just a hint, I never had to deal with it myself.
Of course the possibility remains that the ribbon connector is internally screwed in some obscure way, but it may as well feed corrupted (timing) data to the display.

Telefunky wrote:the PDF manual of the G321ev just explains parts and function from page 9 to 18.
But you already replaced both screen and cable and it didn‘t change the result, so it‘s unlikely the display is faulty.

In MPC Service Manual the bottom left section of the PC IO Block Diagram points to the display connection. Inspect that part of the hardware, in particular in regard to timing.

It‘s just a hint, I never had to deal with it myself.
Of course the possibility remains that the ribbon connector is internally screwed in some obscure way, but it may as well feed corrupted (timing) data to the display.

Hi there, I am able to confirm that the issue is not with the screen itself, but likely the FFC slot (on the board) or perhaps even the motherboard. I have 3 different MPC 4000's and I tested the 2 different screens in two of them and both MPC's apparently have the same exact issue. When I put the screen in another one that I recently acquired, there were no lines.

Another possible solution would be to clean the flux residue on display PCB as I have noticed there is some present on one of my units.

Never noticed flux on my display circuit. Maybe someone tried a repair, worth checking...

In the Service manual (IO VR Schematic) the bottom right section allows tracing of what’s fed into the display cable from connector J8 via an octal line buffer 74hct541.
(it‘s the details of the schematic I mentioned previously)