Upgrading the HP/Agilent 8714C from green CRT to color LCD

[Phoenix Engr]

Here's a list of the part number I ordered. 

U1008 -- LX8385B-33CDD -- 3.3v regulator
Q1001 -- FDS6679 -- P channel MOSFET
R1025 -- SOMC160333R0GEA  -- resistor array, 33 ohms
R1026 -- SOMC160333R0GEA  -- resistor array, 33 ohms
U1012 -- SN74LVT125D
U1009 -- SN74LS123DR
U1010 -- 74LVT574WMX
U1011 -- 74LVT574WMX
J1020 --  A3E-50PA-2DSA(71)

@Andy2000-

Your modifications appear to be the cleanest way to accomplish this.  Would you care to share the wiring diagram between the HP CPU board and the LCD display, or at least a schematic for the 8714 analyzer which does not appear to be available on-line anymore?  Thanks in advance.

Edit:  Just looked at my logic board and there about a dozen other components that show up on Andy2000's pic that aren't on my PCB.  Maybe the best way to go is what the OP did.

[Phoenix Engr]

I ran the 3 coax cables from the VGA connector to the IDC connector.  All I need now is a pin out for this 20 pin IDC connector.  Any help would be appreciated.

[Phoenix Engr]

I was able to map the connector using an Ohmmeter and scope to probe the pins.  The OP said there were only 3 open pins, so I'm still unsure what is connected to pin 16, but all others are accounted for.

That being said, I've drawn a preliminary schematic of an interface board that will go between the IDC20 cable and the LCD VGA input.  I also added a constant current source to provide 100-250mA to a pair of LED backlights using the front panel brightness control.  I stress that this is preliminary and needs to be breadboarded and verified.  Next step is to spin a prototype PCB, order the LCD display and test it.  I will post a link to the PCB fab if/when I verify operation if anyone else is pursuing a similar solution.

[TheSteve]

Very cool that people are still doing a mod like this!
I sold my unit several years ago, it is just a distant memory now.

[Phoenix Engr]

Very cool that people are still doing a mod like this!
I sold my unit several years ago, it is just a distant memory now.

Steve-

You don't by chance have a schematic for the IDC-20 connector that you could share?

[TheSteve]

I made notes when I did the mod, not sure I still have them 11 years later. That is something I wish I had included in the original posts. If I happen to come across my notes I will post the info, but I wouldn't count on finding it.

[Phoenix Engr]

I think I have it all sorted except for pin 16 (maybe some kind of enable signal?).

Thanks for all the work you did on this and for sharing.