trophoblast
New member
This might be a long post...
I recently purchased a Crystalfontz 4x20 negative backlight (green char. on black) serial LCD to go into my car mp3 custom-made plexiglass in-dash head unit (with power and volume knobs ). From my plexiglass mp3 unit in the trunk I have a serial cable and 5V power lead going to the face.
Here's the problem: I just got the face sanded, painted black, and wired up with the volume control so I could install it all in the car. Despite the fact that I tested everything beforehand in my apartment, (and it was all working fine with my Winamp LCD and infrared remote plugins), when I put it in the car nothing happened. The unit worked fine, even with the remote, but the LCD displayed nothing. I pulled it all out again, checked the connections, and still nothing.
I pulled it all out and took it all to my apartment to check with my multimeter...+5V from the computer power supply, no problem. The problem lies with the power cable on the LCD. The ground cable will not work! I get a big fat "0.00" on my multimeter when I test the LCD cables! However, if I directly bridge the power supply ground to the negative solder point of the actual LED backlight connector, I get illumination. Any other way does not work. Also, now I have no characters displaying at all, no matter how I route the ground to make the backlight work.
Something to add: I have not mishandled the LCD in any way; in fact, since it cost my over $70 I've been treating it like gold!
Can anyone diagnose my problem? I am not new to soldering, wiring, or the concepts of a "good ground". This is why I am so perplexed by this problem...it worked fine, then suddenly nothing. Even with all the same wiring, etc. Also remember my LCD is serial, not parallel, so there is no wiring involved besides the power leads. I thank in adavance anyone who might have something to suggest!
(Attached is a pic of my MP3 unit for all who might be curious...)
I recently purchased a Crystalfontz 4x20 negative backlight (green char. on black) serial LCD to go into my car mp3 custom-made plexiglass in-dash head unit (with power and volume knobs ). From my plexiglass mp3 unit in the trunk I have a serial cable and 5V power lead going to the face.
Here's the problem: I just got the face sanded, painted black, and wired up with the volume control so I could install it all in the car. Despite the fact that I tested everything beforehand in my apartment, (and it was all working fine with my Winamp LCD and infrared remote plugins), when I put it in the car nothing happened. The unit worked fine, even with the remote, but the LCD displayed nothing. I pulled it all out again, checked the connections, and still nothing.
I pulled it all out and took it all to my apartment to check with my multimeter...+5V from the computer power supply, no problem. The problem lies with the power cable on the LCD. The ground cable will not work! I get a big fat "0.00" on my multimeter when I test the LCD cables! However, if I directly bridge the power supply ground to the negative solder point of the actual LED backlight connector, I get illumination. Any other way does not work. Also, now I have no characters displaying at all, no matter how I route the ground to make the backlight work.
Something to add: I have not mishandled the LCD in any way; in fact, since it cost my over $70 I've been treating it like gold!
Can anyone diagnose my problem? I am not new to soldering, wiring, or the concepts of a "good ground". This is why I am so perplexed by this problem...it worked fine, then suddenly nothing. Even with all the same wiring, etc. Also remember my LCD is serial, not parallel, so there is no wiring involved besides the power leads. I thank in adavance anyone who might have something to suggest!
(Attached is a pic of my MP3 unit for all who might be curious...)
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