Question about older display, LCD2041..

LK/ELK/VK/PK/OK/MX/GLK/EGLK/GVK/GLT Series

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rys
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Question about older display, LCD2041..

Post by rys »

Hello,
I purchased a LCD2041 v1.4 (4x20) lcd a few years ago and it worked flawlessly but I never really had the time to use it for the project I had in mind. Over the past week I found it and decided to devote some time to this project.

I had to seperate the two boards and solder extention cables between them (using about three inches to do this) and I also soldered together my own serial cable for the project.

At this point the lcd works perfectly the only issue i am having is the backlight isnt turning on (I have tried sending it commands through LCDC).

I realised that when creating the serial cable I ran pin 7 as ground instead of pin 5 but I am not sure if that is the problem.

If I were to take a LCD2041 and ONLY apply the power to it should the backlight turn on or does it need a complete serial connection?

Thanks for any advice and insight into this matter

rys
Last edited by rys on Wed Oct 05, 2005 3:36 pm, edited 1 time in total.

Tom
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Post by Tom »

Hi rys,

There can be a few factors involved in getting the backlight to work. You may want to check connections on pin 15 and 16 of the display. Those pins are for the backlight. There can possibility be a bad component, but we should take things a step at a time before jumping to if it is a bad component.

What you would want to do is use pin 7 as a ground. When wiring communications, it is a good idea to wire up the ground too.

If you do just apply power then the backlight should turn on.

Hope this gives you some extra insight. Check the connections on pin 15 and 16 first, then we can move on from there.

Best Regards,

rys
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Post by rys »

Tom wrote:Hi rys,

There can be a few factors involved in getting the backlight to work. You may want to check connections on pin 15 and 16 of the display. Those pins are for the backlight. There can possibility be a bad component, but we should take things a step at a time before jumping to if it is a bad component.

What you would want to do is use pin 7 as a ground. When wiring communications, it is a good idea to wire up the ground too.

If you do just apply power then the backlight should turn on.

Hope this gives you some extra insight. Check the connections on pin 15 and 16 first, then we can move on from there.

Best Regards,
Thanks for your response Tom,

I just rechecked all of the wires (just incase) and all pins including 15&16 have a positive connection.

When I apply power (12v) to the LCD at this point I will get a flashing block and no backlight.

Tom
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Post by Tom »

Do you have a multimeter?

rys
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Post by rys »

Tom wrote:Do you have a multimeter?
Yes

Tom
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Post by Tom »

When you turn on the backlight with a program like uproject, the backlight should show 5V. I have showed the location of where it should read 5V. If you have the upper left pin of the transistor reading 5V and the right side of the transistor, which is connected to pin 16, 0V, then you have a bad transistor. If you get 5V, then there is something wrong with the display. The picture below will illustrate the location of the transistor.
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backlight.JPG
backlight.JPG (45.56 KiB) Viewed 9117 times

rys
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Post by rys »

Tom wrote:Are you certain you have a 12V unit?

When you turn on the backlight with a program like uproject, the backlight should show 5V. I have showed the location of where it should read 5V. If you have the upper left pin of the transistor reading 5V and the right side of the transistor, which is connected to pin 16, 0V, then you have a bad transistor. If you get 5V, then there is something wrong with the display. The picture below will illustrate the location of the transistor.
I am not positive it is a 12v model but when I apply 5v it just shows two bars across the screen (its 4x20 not 2x20 as i said earlier but im sure you know that) and if I apply 12v it shows the blinking block..

I actually have the 1.4 model and the back is alittle different
Image

Miles
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Post by Miles »

Hi rys,

I think I may see your problem. Please ensure that 2 jumps are made accordingly for the backlight as shown in the following picture. Let me know if this works!! :D
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Miles Y.
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rys
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Post by rys »

Miles wrote:Hi rys,

I think I may see your problem. Please ensure that 2 jumps are made accordingly for the backlight as shown in the following picture. Let me know if this works!! :D
Image

Thanks to both of you for your help :)

I completely forgot about those jumps (now that I think about it there was a dot of solder there and I wasn't sure if it belonged)

Excellent customer service :D

Tom
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Post by Tom »

Glad everything worked out for you.

If you need anything else, let us know.

Best Regards,

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