After I got my 8753ES working I was a little disappointed in the LCD brightness, especially right when you turn it on.? I also didn't think the viewing angle was great; a little off to the side and it really dropped off.? The main problem seemed to be that the CCFL backlight was old and needed replacement.? The panel is a Sharp LQ084V1DG22 but unfortunately I couldn't find an online source for a replacement bulb, which is a special L shaped one to light two sides of the display.? I did find a LED retrofit on ebay:
But yikes, $93 plus $11 shipping?? That's $104, for a backlight? That just seemed wrong to me.? So I did some further research and found that while the LQ084V1DG22 is no longer manufactured, there is a somewhat compatible new version made, a LQ084V1DG43.? The actual display has the same dimensions and mounting alignment features and is not as thick.? It has a LED backlight and improved viewing angle!? And it is $100 shipped!? That's $4 cheaper than the replacement backlight!? Here it is:
So I ordered it and also went online to get the data sheet.? There is one incompatibility from the original:? the LED backlight takes 12 volts and uses this really tiny JST connector.? Well, the backlight inverter in the instrument runs on 5 volts and there isn't 12 volts available.
First problem was that JST connector.? They are really inexpensive but good luck getting them.? Digikey had the shells but no crimp pins.? Mouser had neither in stock.? Some other places had them but large minimum orders.? I went to the JST site and found a page where you could order samples!? Sure enough they arrives several days later.
When I said tiny I meant it; these things require assembly under a microscope.? 28 AWG wire is almost too big, certainly too big to crimp the terminal around the insulation and still have it go in the housing.? I cut off those crimp ears and just crimped around the bare wire then soldered.? Count on using the smallest tip and the solder which you use for doing rework on 25 mil pitch surface mount boards.? It took me several to get it right.
There are brightness and enable inputs for the backlight.? Both default to on and full brightness if not connected so you only need 12 volts.
I tested and yes it lights up.? I then plugged it into the instrument (without installing mechanically) and it worked!
I then took the old display out.? It has some thick black gasket around the active area which was too crumbly to reuse.? As the new LCD is thinner, and held to the front panel by a piece of sheetmetal, I had to use foam rubber tape to make up the extra thickness and keep the new LCD from moving around.? I am not sure I like that I can see the unpainted frame of the new LCD so I may try and neatly put black tape around it where it's visible, mainly on the top.
For now I just used a bench supply to do the final test of how it looks.? I will deal with the 12 volts tomorrow, probably a new 7812 off of the raw +18 or something (it needs about 250 mA).
Wow!? The brightness is dramatically different!? It's fantastic now, and the viewing angle is tremendously improved.? If you're up for dealing with the tiny connector and the 12 volts this new LCD makes a dramatic difference.? Additionally, the LED backlight had a long enough life that I will never have to worry about it again.
Peter
