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633 backlight

JSchuricht

New member
I have had my 633 for several years now. Unfortunately, the backlight is no longer producing enough light to read the LCD. What would it cost to fix this? Who should I contact?
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JSchuricht

New member
To answer my own question, partly… they are listed as white edge LEDs in the data sheet.

If it helps any, with a bench power supply I am getting 5.11v at the floppy connector, and (left to right according to pic) 9.9v, 5.87v, 5.89v, 1.92v to ground and 4.04v, 3.99v on the individual leds. What should the voltages be?
 

JimBowen

New member
I think you'll find the answer to your question in this thread.
I predict I will have the same problem with my LCD in the not-too-distant future, as all of the blue/white LCDs burn out after ~= 6 months of full-brightness backlight use. ;_;
 

JSchuricht

New member
I removed the old LED’s. Correct me if I am wrong, but it appears that the LED’s are running series with a 12v supply. Aren’t the LED’s typically ~3v ea? I would think that giving them 6v ea would burn them out quickly.
 
USB LCD Displays - Graphic and Character LCDs with a Keypad

JSchuricht

New member
Went with the Panasonic LNJ026X8BRA. The LCD is legible once again.

For anyone attempting this, I used a Weller SES50 @600°F with a 1/64” long conical tip. The area that I ran into trouble in was rotating the LED’s so the polarity was correct. I found that the continuity setting on my multimeter would power the LED which made it easy to determine which end was positive and negative.

CF Tech, what brand LED’s are stock on the 633?
 
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