I need some good video advice ( external video for a Icom 756pro )

Discussion in 'Homebrew and Kit Projects' started by W6VHK, Oct 7, 2016.

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  1. W6VHK

    W6VHK Ham Member QRZ Page

    i am working on an interesting project involving an Icom 756 pro transceiver and need to replace the small Icom tft display with a much larger 10.4" display.

    While I am very good at repairing all different kinds of electronic equipment I have never had any experience involving video ...lgb. tft. etc .....

    I remember reading a thread sometime ago where someone wanted to use a external display with a 756 pro ( like the Icom 7000 ) and someone answered and said it would be very easy but apparently nothing ever became of it.

    If you want to take a look at the 756 pro service manual, see: http://www.radiomanual.info/schemi/IC756PRO_serv.pdf ( see schematic almost down at the bottom, lower right side ) you will see the display connections.

    Can anyone help?


    Darrell / W6VHK
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    What page of the schematic are you looking at ?

    I can not be much help, But that radio does not look like it has a Video output.

    My guess you could have it connected to a computer and use the computers display.

    Have Fun.
  3. W6VHK

    W6VHK Ham Member QRZ Page

    756pro's don't have a video output, hence my question ...

    The output from the main board to the display has the following connections:
    1) gnd
    2) hd
    3) vd
    4) polc
    5) gnd
    6) l5v
    7) rl
    8) gl)
    9) bl
    10) vcom
    11) gnd
    12) l/r
    13) u/d
    14) n/p
    15) l18v
    16) -15v

    What would be the best way to convert this to composite ?
  4. KW4EK

    KW4EK Premium Subscriber QRZ Page

    If you are lucky the display interface might be VGA (or, possibly, a so called LVDS flat panel interface), in which case you may have the option of using a VGA display without excessive difficulty. However, if it is not a true compliant interface then you enter the realm of needing to custom design an intermediate interface to compete the conversion to a known format which can be trivial if it only requires level shifting to extremely difficult if it requires wholesale conversion using an FPGA or DSP, along with the headache of programming such devices. Your best bet to find out what interface was used is to begin with the actual display module used in your radio and find its manufacturer datasheets and any other specification documentation you can turn up. Composite video is a pointless quest as composite lacks the resolution and clarity for a clear display, but VGA, if an option, would certainly be workable.

    However, judging from a quick look around those displays look to be difficult to source should you damage your existing display you may find yourself with a next to useless radio. Nor is it as simple as just wiring up an external monitor with the required cable and port shielding as you also have a number of soft function buttons encircling the display that would also need to be brought out to the new external display if you are to preserve the usability of the radio and display. Plus it will likely be an awkward final interface with the function buttons mounted to a remote monitor and all the rest of the radio controls still on the radio, meaning a lot if going back and forth.

    Provided that your radio has a functioning display at present I can not fathom the point of risking damage to a possibly difficult to source display module or the damage a novice electronics technician (I do not know your actual skill level, you will have to be your own judge) may inflict upon a perfectly good HF radio in the course of all the necessary mods. It is a solution that really only makes sense if a bad display module has bricked an otherwise perfectly good rig.

    What, precisely, are you trying to achieve and why? As a general rule projects like this fall under the heading of "if you have to ask...". They are generally only advisable for experienced electronics technicians who are OK with the reality that if they make any mistakes they may either junk a perfectly good radio or are prepared to invest the many hours that sometimes go into repairing any damage inflicted (which requires considerable knowledge, skill, and test gear to diagnose and effect repairs), provided parts are still available and such damage us not too extensive (even the very best can make some pretty epic mistakes once in awhile).

    The big question, though, is why? Most of the front panel functionality is readily available and duplicated with modern rig control software (such as Ham Radio Deluxe). If further combined with an RTL-SDR dongle tied into the radio's IF to form a proper Panadapter you can greatly exceed the capabilities of the radio's own front panel display.

    If you better describe what end result you are really seeking you may find that there are better ways to go about obtaining such functionality without risking damage to your radio through possibly extensive modifications just to achieve a larger display.

    Whatever you end up doing, I wish you all the best in your quest.
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    For CGA and VGA these are the pinouts.



    Just a guess of what might work. Verify using a O-Scope.

    Radio side connections,

    Pin1 Ground

    Pin 2 and 3 would be Horz and Vert.

    Pins 7,8 and 9 would be Red, Green, Blue.

    If RGB has sync on them then a composite 1V p-p signal may be had.


    Ethan has a valid point, Proceed with care.
  6. W9GB

    W9GB Ham Member QRZ Page

    The Display for their earlier Icom IC-756 used a low resolution display (320x240 Graphic display).

    This is NOT the project for the Novice or weekend hacker --
    and often the DIY hack is far more expensive ($$, time) than buying correct replacement part ($$).

    Newhaven Displays, based in Elgin, IL handle a variety of Eastern Asian displays and "retrofits" for various USA industries (manufacturing, health-care/medical, automotive, aerospace).
    They speak English, and you don't have to wade through numerous Taiwan and Chinese manufacturers (who don't aleays speak English).

    They stock a number of "Widgets" for conversions and support of various "retrofits"
    for the electronics bench technician.

    The "display controller" for the radio makes a big difference in "ease of replacement".
    You can post your "customer project" on their forum, but don't expect 'free handouts'.
    Last edited: Oct 8, 2016
    AH7I and KA9JLM like this.
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    320x200 was the closest to NTSC composite video. The C64 modulated it for channel 3/4, In the good old days.

    CGA or VGA would be the one to try, since it is color and the display looks like 320x240.

    A O-Scope can tell you what is going on. You should never hack without one.
    Last edited: Oct 8, 2016
  8. W6VHK

    W6VHK Ham Member QRZ Page

    From a thread several years ago someone asked the same question and someone answered ( a "cut and paste" from that thread ).....

    Contrary to what others have said. You should be able to mod the pro 3 for and external display.

    Last year I took a look at the display subsystem of my Pro-3 and if I remember correctly the output of the video driver that is driving the internal display was not an Icom proprietary system as I originally expected it to be. It was in fact an older standardized video system that could be easily converted to VGA. All that would be required to add an external display would be to tap into the video output at the flex connectors and route the signal to a simple home brew converter and out to a VGA connector at the back of the rig,

    Now there was something unusual about the video standard but I don't recall off hand what it was, I think it had something to do with timing but I would have to find my notes to be sure.

    I did not investigate further because I really didn't see a need for a larger screen. I was just investigating the possibility of adding an external display should the internal display ever fail. From what I have seen it seems as though with about $20 worth of parts and a half hour of bench time the pro-3 could easily moded for an external display.

    On my 756 Pro the display driver ( IC-1401 ) is a M52338FP ( Icom service manual section 10-1 lower right corner of the page ).

    As I said, I am working on a project that requires a 10.4" display and am looking for someone who really knows video to tell me if it is possible and what I would need to do it.
  9. W9GB

    W9GB Ham Member QRZ Page

    IF you look at the Pinball/Arcade industry, they have had to address video issues as
    CRT monitor subassemblies are now limited to speciality restorers and re-manufacturers ($$).

    There are CGA to VGA converter modules/sub-assemblies that can reduce the reverse engineering and re-design for external monitor support.
  10. VE3TMT

    VE3TMT Ham Member QRZ Page

    Looking at the schematic, the red, green and blue outputs are available on J531 of the PRO3's display board. Would it not be a simple matter to run these lines to the outside world and feed either a component to DVI or HDMI converter and then to an external monitor? Would it drain the color on the internal display? It seems to me all of the work would be done by the M52338FP (contrast, brightness etc), all that would be required would be getting the component signals to the outside.

    I'm looking at replacing the CCFL tube in my PRO3 with LEDs. My display is still bright after about a 10 minute warmup but this may be an easier approach.


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