Products > Test Equipment
Upgrading the HP/Agilent 8714C from green CRT to color LCD
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KrudyZ:
In the last picture you can see that I am using the original CRT mounting studs and its washers and nuts as a spacer.
The acrylic has matching holes to align the LCD. The LCD assembly is simply held in by the front bezel pushing it onto the studs.
Really easy to take apart that way.
AF6LJ:
That looks really nice.  Great work.
KrudyZ:
Yesterday, I got a replacement for the video DAC I had blown up by connecting the red channel to 12V instead of the adjacent pin on the ribbon cable where it was meant to go.
I snipped out the broken DAC which was the easiest way to remove it due to its PLCC44 package.
With the new one in place I got the exact same problem, say what?
Turns out that my replacement protection diode I had put in earlier wasn't a BAV99 as its bag label suggested, but a common cathode dual, so the red channel was now shorted to the 5V protection rail.
Just goes to show that you have to check everything... Luckily, this did not kill the DAC since its output is a current source and the part runs off of the same 5V.
After replacing the diode with a real BAV99 I finally got my red channel.
Now all looks good. Still waiting on getting the LED strips for the backlight.

I'm a bit shocked that the little 75 Ohm source termination resistor survived having 12 V across it, i.e. almost 2W of power... There wasn't even any discoloration.
Interesting side note, the VGA to LCD converter goes through some kind of calibration to measure the incoming video stream and centering the image. It also seems to be doing some black and white level adjusts. You can actually see the image quality improve over the first few seconds after turn-on.
AF6LJ:
Very nice  Love it.
BFX:
Excellent!  :-+
I'm still curious what is difference between my 8713B and 8714C regarding to this color output.
I Haven't time to investigate that yet, but if anybody knows please let's me know.
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