Author Topic: Upgrading the HP/Agilent 8714C from green CRT to color LCD  (Read 12523 times)

0 Members and 1 Guest are viewing this topic.

Offline coromonadalix

  • Super Contributor
  • ***
  • Posts: 2849
  • Country: ca
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #25 on: June 05, 2018, 10:25:33 am »
Nice  :-+
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #26 on: June 05, 2018, 12:29:49 pm »
Nicely Done!
I have a Marconi service monitor I need to do that mod to.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline KrudyZ

  • Regular Contributor
  • *
  • Posts: 192
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #27 on: June 05, 2018, 05:01:43 pm »
Nicely Done!
I have a Marconi service monitor I need to do that mod to.

Well, I haven't really done anything, yet. :D
The hard part is still ahead, milling the inside of the front panel flat.
It is concave to match the curvature of the CRT, but the LCD is of course flat.
Luckily, I have a milling machine available, which should help a lot.
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #28 on: June 05, 2018, 07:02:00 pm »
Nicely Done!
I have a Marconi service monitor I need to do that mod to.

Well, I haven't really done anything, yet. :D
The hard part is still ahead, milling the inside of the front panel flat.
It is concave to match the curvature of the CRT, but the LCD is of course flat.
Luckily, I have a milling machine available, which should help a lot.

Simple operation for you.
The set-up on this would be interesting to see.
Hopefully that bezel is some kind of metal; I would be a bit afraid to mill on thirty plus year old plastic.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline TheSteve

  • Supporter
  • ****
  • Posts: 3164
  • Country: ca
  • Living the Dream
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #29 on: June 05, 2018, 10:21:49 pm »
The front is plastic, it mills beautifully - even with its age. This is such a huge upgrade for this NA, the color LCD really makes it a pleasure to use.
VE7FM
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #30 on: June 05, 2018, 11:00:35 pm »
The front is plastic, it mills beautifully - even with its age. This is such a huge upgrade for this NA, the color LCD really makes it a pleasure to use.

Very cool looks Great.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline eb4eqa

  • Regular Contributor
  • *
  • Posts: 90
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #31 on: June 07, 2018, 10:53:47 pm »
Well done! It looks great.  :-+ :-+

Roberto
 

Offline KrudyZ

  • Regular Contributor
  • *
  • Posts: 192
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #32 on: June 10, 2018, 01:46:17 am »
I ended up using a router table instead of the milling machine, since the plastic is flexing and generated chatter on the mill.
It was pretty easy to maintain a steady downward pressure on the router table to avoid the chatter.
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #33 on: June 10, 2018, 11:36:51 am »
I was wondering how a mill would work given that peace would flex a lot.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline KrudyZ

  • Regular Contributor
  • *
  • Posts: 192
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #34 on: June 11, 2018, 05:02:54 pm »
I put together the LCD module with some laser cut acrylic, a frame and a back board with holes to mount the electronics.
The only custom part is the 20 pin header to VGA plus power adapter board. I did not make any mods to the video converter board.
I was toying with the idea of keeping the VGA cable connection and not going through the ribbon cable. In retrospect I wish that I had done that as I soldered the red coax to pin 2 instead of 1 of the 20 pin header AND DID NOT CHECK MY WORK.
That shorted the red channel to the 12 V supply and blew up its channel on the video DAC plus a protection diode :--
It's an obsolete part, but available on ebay. The green and blue channel are still working, so I can still use the instrument, but damn annoying to make such a silly mistake.
As an aside, on my board the protection diodes for the VGA are individual dual diodes. The schematics show one big 14 pin device to protect all the lines. At least I got lucky on that one as it's easier to replace...
 

Offline KrudyZ

  • Regular Contributor
  • *
  • Posts: 192
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #35 on: June 11, 2018, 05:06:08 pm »
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.
 

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #36 on: June 16, 2018, 08:59:56 pm »
That looks really nice.  Great work.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Offline KrudyZ

  • Regular Contributor
  • *
  • Posts: 192
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #37 on: June 22, 2018, 04:53:03 pm »
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.
 
The following users thanked this post: AF6LJ

Offline AF6LJ

  • Supporter
  • ****
  • Posts: 2903
  • Country: us
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #38 on: June 23, 2018, 02:59:24 am »
Very nice  Love it.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Online BFX

  • Frequent Contributor
  • **
  • Posts: 368
  • Country: sk
Re: Upgrading the HP/Agilent 8714C from green CRT to color LCD
« Reply #39 on: June 24, 2018, 02:32:26 pm »
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.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf