Display replacement trouble

Thread Starter

hide24

Joined Jul 9, 2019
45
Hi everyone,
I need to replace a display of my Korg T3 synthesizer to one with backlight.
I took a new LCD from a old mixer KORG D12, (both are a 240x64 dots and they have the same number of pins 22 )
The question is:
The new lcd from the mixer not use a small cable (grey, with 2 thinners black and white), but the original yes.
Onething I noticed is the last pins 21,22 in the new display are not connected because the ribbon has 20 pins.

How can I connect it to make it work the backlight?
I pluged to my synth and seems to work, but not backlight.

I attach some photos.
Thank you very much.
 

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Last edited:

ericgibbs

Joined Jan 29, 2010
9,799
hi 24,
On the new LCD there are two pins marked A and K, ref image, compare them to the old LCD for polarity.
I do not know if there is a series resistor onboard, so I would advise a low value resistor in one of the light leads, say a 120R, while testing.
E
 

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Thread Starter

hide24

Joined Jul 9, 2019
45
Thank you Eric,
Are the black and white thin cables I should weld?
And about the resistor how should I weld too? For example at the top of the black cable?
 

ericgibbs

Joined Jan 29, 2010
9,799
hi,
Go onto this link for the old LCD, you will see the light wire location and colour, put the resistor in the A-node wire.
Use the same pin notation for the new LCD ie: A and K
Place your cursor on the Amazon image and it should enlarge.
If the light is not bright enough try a lower value resistor, say a 47R

yes, the black and white thin cables I should weld?


https://www.amazon.com/Optrex-DMF5005N-Display-Parallel-Backlight/dp/B016YJUVKE
 

Thread Starter

hide24

Joined Jul 9, 2019
45
Should be something like this? (photo below)
What are those gold holes in the middle of the display, between A and K?
Also what is the function of the resistor in this case?
Thank you!
 

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ericgibbs

Joined Jan 29, 2010
9,799
hi,
I am unable see any connecting track from those holes to the A K pads.? The 'holes' do not show as being all the way thru the PCB, on the photo's
If you have a test meter you could measure between the A K and those pads, check for continuity.
E
 

Thread Starter

hide24

Joined Jul 9, 2019
45
I tried now with the resistor and conect the cables to A, and K but seems the backlight don't want to turn on..
 
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