(Seiko) M4024 LCD Display doesn´t work


New member

I bought a 4x40 LCD at Ebay,i think it is new.
I only know that is a M4024 Display with 2 KS0066(F00) controllers.(eventually manufactured by Seiko?)
My Ebay-Partner sent me a wiring schematic and the specifications,it looks like it is a part of this PDF-document:

http://www.glyn.de/New_home/Produkt...heets/Seiko_Instruments/SI_Manual Italien.PDF

I think i have done it correctly,but the display shows nothing.
Afraid from the feeling i have it broken i searched at google for websites about it.
I found a data sheet for a display like my one,but with other pinouts.
In the datasheet i got from Ebay are lcd-pin 1-8 D0-D7,in the other they are D7-D0.
The other connections are the same.
What´s the right pinout?
I wired it on the 1 th and by the 2nd way,but it still shows nothing.
The only effect i have watched is that the first of the 2 KS0066 controllers becomes a little bit warm.(not hot)
Why i can´t see anything?
It is a possible matter that i not connect a potentiometer between the +5V and the VLC-pin at the display?

Please help me!

(...sorry for my very bad english!)
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Last edited:


New member
Now I can see something...

Hello again,

the problem with the contrast is fixed.
When powering on the display the first and the third row are black.
I used the program lcdprint.exe for testing.
When i use the original wiring schematic with PIN1 to DO,PIN2 to D1...,the Display shows nothing.
The other wiring schematic "works" a little bit.

When i enter

lcdprint 378 40 4 c:\mytext.txt

the display become completely grey.


When I enter

lcdprint 378 4 40 c:\mytext.txt

are only the third line black.
I think the display is not broken,but what ist the problem with it?

You can find the other datasheet here:

(The Display is named there as L4044,but it is the same as the M4024)
Last edited:


New member
Thank you so much!


the program that link you postet helped me more than anything other.The possibility to set the bits manually helped me to find out that my LPT1 is damaged.
Several Bits don´t switching to high.
I tried the display on another machine and it works fine.
I think i have to buy a IO-card for my main machine...

Thank you for helping me,