MOP-GL24064R-BSSX backlight not functioning

envisionelec · Post by **envisionelec** » Wed Jan 12, 2011 5:47 pm

I just purchased a MOP-GL24064R-BSSX and the backlight will not illuminate no matter the configuration. Diode test on the green LED, for example, show 2.7V in the correct polarity and 1.7V in the other. According to the datasheet, the LEDs are passively driven (externally). Am I missing something?

Clark · Post by **Clark** » Thu Jan 13, 2011 2:03 pm

Hello Envisionelec,

Our backlight LEDs are powered with 5v, using a resistor inline to take the excess voltage and control the current going into the backlight. Taking the green LED on your tricolour display for example, we apply 5v power to one side of the resistor, and see a drop to approximately 3v on the LED anode side. We have chosen a 47 ohm resistor to control the current to approximately 60mA as specified. The single cathode pin is connected to ground.

I have noted that the manual posted is missing values for the specific red, green, and blue backlights of your tricolour display and will have that information added in the next revision. For now I have added the current, and min/typical/max voltage values for all three backlight LEDs.

IF(R)=40mA 1.9V 2.0V 2.1V
IF(G)=60mA 2.8V 3.0V 3.2V
IF(B)=60mA 2.7V 2.9V 3.1V

Should you have any further questions or concern as you continue to develop with the MOP-GL24064R, please don't hesitate to post or contact me directly.

Thanks,
~Troy

envisionelec · Post by **envisionelec** » Thu Jan 13, 2011 2:21 pm

Clark wrote:Hello Envisionelec,

Our backlight LEDs are powered with 5v, using a resistor inline to take the excess voltage and control the current going into the backlight. Taking the green LED on your tricolour display for example, we apply 5v power to one side of the resistor, and see a drop to approximately 3v on the LED anode side. We have chosen a 47 ohm resistor to control the current to approximately 60mA as specified. The single cathode pin is connected to ground.

I have noted that the manual posted is missing values for the specific red, green, and blue backlights of your tricolour display and will have that information added in the next revision. For now I have added the current, and min/typical/max voltage values for all three backlight LEDs.

IF(R)=40mA 1.9V 2.0V 2.1V
IF(G)=60mA 2.8V 3.0V 3.2V
IF(B)=60mA 2.7V 2.9V 3.1V

Should you have any further questions or concern as you continue to develop with the MOP-GL24064R, please don't hesitate to post or contact me directly.

Thanks,
~Troy

Of course. I'm quite familiar with the operation of LEDs. So, if it still doesn't work - what are my options? There's no negative bias output, either. Should I assume the panel is defective?

I've emailed you directly. I work from all angles.

Clark · Post by **Clark** » Thu Jan 13, 2011 2:53 pm

No worries, I have received your email, I don't mind at all if you try all angles, but please understand that I would much rather respond from just one. If we find anything interesting I'll be sure to add it to this thread.

Thanks,
~Troy

envisionelec · Post by **envisionelec** » Fri Jan 21, 2011 11:31 pm

Clark wrote:No worries, I have received your email, I don't mind at all if you try all angles, but please understand that I would much rather respond from just one. If we find anything interesting I'll be sure to add it to this thread.

Thanks,
~Troy

To follow up, the display was, in fact, faulty on a number of fronts. The next two worked perfectly.

Thanks, Troy.

Clark · Post by **Clark** » Mon Jan 24, 2011 11:16 am

Good to hear the replacement and the new unit are working out much better for you. Getting an MOP unit up and running is tricky, now that it is I don't expect any more trouble but if you run into anything more please let us know.

Thanks,
~Troy