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Backlight on CFAH1602B-YYH-JPV

heyus

New member
I've had my CFAH1602B-YYH-JPV ( 2x16 wide-temp green backlit) since around October of 2001 and recently I've noticed areas of my LCD backlight going dark. I'm assuming that the backlight is going out from overuse and am wondering if there is a way to turn off the backlight and/or change the backlight 'bulbs'.

Thank you
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CF Tech

Administrator
Can you let me know what schematic you used, and the value of the LED backlight dropping resistors?
 

heyus

New member
Well, I have nothing hooked up to do anything to the backlight because my A and K terminals had no effect on the backlight... however, I am using the negative voltage generator to run to the 10k pot for my LCD contrast.
 

CF Tech

Administrator
Is the backlight on at all? It would have to be powered by the A & K then, right? I do not mean to be thick, but I do need to know how the connection is made to the backlight, and what kind supply is connected toi the backlight.
 

heyus

New member
The backlight is on constantly and, as far as I can tell, receives its power from the LCD itself, rather than terminals A/K/15/16.
 

heyus

New member
Things have gotten even worse...

I've now had my CFAH1602B-YYH-JPV for just under 5 months and I'm down to one of the 5 or 6 lights that power my backlight. One of the other light sources flickers occasionally, and the rest just don't come on at all. I'm really quite disappointed seeing as the documentation on the LCD says I should get 100,000 hours out of it. I've checked all the voltages and its not being hit with anything out of the recommended ranges. The temperature stays within 60 to 100 degrees fahrenheit so that's not it.

I talked to an electronics technician who said that after reading over the documentation, I must have gotten a faulty LCD seeing as it was impossible to turn off the backlight and that it should not be anywhere near failing at its current rate of use of 5 hours a day.

The LCD is used in a dim environment and seeing as the LCD is not reflective, its getting near impossible to read.

Any suggestions or comments on return policies? :)

Thank you
 

CF Tech

Administrator
I still can't make sense of how the backlight is coming on at all with the connection made as they are. Can you take a high-res pic of the back of the LCD showing the connections?

If not, please contact returns@crystalfontz.com and we will have to work something out. Do not disconnect the LCD, as we will want to see how it was connected.
 

heyus

New member
I don't have a camera, so I'll list off what each pin is connected to. I'll try to get a camera from a coworker tomorrow if possible.

CFAH1602B-YYH-JPV as listed on the sticker on the back

16 pins

Pin 1: ground
Pin 2: +5v power
Pin 3: from 10k pot for LCD contrast
Pin 4: computer
Pin 5: ground
Pin 6: computer
Pin 7: computer
Pin 8: computer
Pin 9: computer
Pin 10: computer
Pin 11: computer
Pin 12: computer
Pin 13: computer
Pin 14: computer
Pin 15: to 10kpot (neg voltage generator)
Pin 16: -nothing-

The writeup for this model LCD only shows the backlight on, which leads me to guess that A and K are powered via the LCD's +5v power on pin 2.
 

CF Tech

Administrator
Thank you for the photos. This is a very odd situation, where some dies in the backlight have failed.

Please contact returns@crystalfontz.com for an RMA request and we will take a look at it here. Do not disconnect the LCD, as we will want to see how it was connected and once we figure out the problem, we will probably put a new backlight into your module.
 
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