Monday, December 11, 2017

Display Transplant into an Icom IC-756 (non-pro)



 The display has a more brilliant color than this, my phone cam just doesn't do it justice!

This blog is about replacing the LCD display in a Icom IC-756 classic. The displays in these radios haven't been supported by Icom in several years. This is an attempt to archive info & notes from myself and others about different displays used. I'll probably add to / edit this blog as I continue to test & install more displays. If you damage something while trying this, don't blame me...these are only notes I've posted from several installations I've done, and feedback from others who have done the same. This is long, read it all. The new info and updates are near the bottom.

I've included connection info on displays I've previously used, as some are still floating around on eBay and such. The most current display I use is from Yuxian, described later.


Winstar WG320240D-TMI-TZ# display (LONG LEAD TIME!): When installing this model, I had tried to drive the display contrast input (display pin 13) from the 756 contrast output (DV0, radio pin 1). It works, but over the period of an hour or so, one has to go into the radio menu and readjust the contrast setting. It seemed to be a thermal drift of some sort in that circuit. After working with the mfg, I discovered a few things:

1- The display generates it's own -25vdc and outputs it to pin display 12. The -30vdc from the radio pin 2 should not be connected to the display. The display is temperature compensated and it varies the -25vdc output at display pin 12 accordingly.

2- When driving display pin 13 from the radio, it ignores the display's temp compensation, thus causing the contrast "drift" or instability. Installing a linear potentiometer of 15k, high side to pin 12, low side to pin 14, and wiper to pin 13 allows the display contrast input to reference the temperature compensated internal -25vdc supply of the display, and I've found the contrast to be perfectly stable. Keep the pot as close to the display as possible, leads short...

3- I prefer to have the contrast adjustment where it can be easily reached, as contrast is somewhat subjective and based partially on the viewing angle. An internal pot is fine, but I like to be able to adjust it easily. I found the lower LH side of the cabinet (just below the handle) to be a good, easy-to-reach location for this. When mounting the pot somewhere that requires a few inches of wire to make the connection, install a 100pf capacitor across the high and low connections to the pot. The -25vdc output of the display acts like a nice antenna to radiate processor noise to the rest of your rig, and I found 100pf seems to be adequate to resolve the issue.


 100pf cap across high and low terminals of the remote contrast pot I installed in this radio...

4- Source a +12vdc switched point to build the 5vdc regulator for the LED back light. ***NOTE*** I now pick up +5vdc for the back light from pin 12 on the cut board, and use an internal 5v regulator in the radio. The newer display back lights require only about 100 mA. No need to build another 5v reg circuit. I use the point from the 4-pin rear panel  accessory port. Use a 7805 regulator and heat sink to chassis, and a 33 ohm 1/2 watt resistor in series with the output to the back light, to limit the back light current. Open coil L103 along side of the HV compartment to shut the CCFL HV supply off when using displays with LED back lights. (I no longer disable the CCFL supply like this, much testing has proven the cfl supply to not be a significant noise source.)

5- If you plan to buy a Winstar display, try to locate the WG320240D-TML-TZ# instead of the WG320240D-TMI-TZ#, it is more easily viewed from above the radio.

(DISCONTINUED) 6-  APlus Displays: AG320240D-TTI-TZ# seems to be the same as the Winstar display


(DISCONTINUED) Stanley GMF32024ABTW1X: The Stanley display found by Rick K4PQ is by far the easiest to install electrically (no back light mods required and seems to be temp compensated in some other way) . This has been the easiest display to install to date, but availability seems to now be an issue...

1- Contrast setting is very stable, the current requirement at display pin 13 is only a few MA (contributing to stability).  Connect the -30vdc supply from the radio to display pin 12 via 2k 1/2 watt resistor. Be sure to turn the trimmer down on the sub-logic board to about the 9 O'Clock position.

2- The back light is directly driven from the radio CCFL HV supply with no mods. This is not a polarized connection and polarity is not important. No back light supply mods needed!

3- This display has the best viewing angle of any of the displays I've tested / installed. It is viewed from above the radio easily, best of all the displays I've tested in this blog.

Can anyone find another source of the Stanley display GMF32024ABTW1X ??

I'm waiting on a East Rising ERM320240SBS-1 to test now. It also looks like the New Haven NHD-320240WG-BxTGH-VZ#-3VR will work, but much more expensive.

*** Update*** Another person bought a New Haven NHD-320240WG-ATMI-TZ# display, and it was MUCH too wide. Avoid that model. Try to choose displays that have a max board width of around 142mm wide and 96mm tall (although board height isn't as critical)


Folks have physically installed these various displays in the metal sub-chassis a number of ways from building brackets, re-drilling holes, etc. I prefer the Hot glue method recommended by Rick K4PQ...quick, easy, and very solid.

I use the Dremel tool to remove the little folded edge from the sub-chassis for best fitment...


When disassembling the face of the radio from the sub-chassis, I've found cutting small cardboard tabs and inserting under the clips around the perimeter makes removal much easier.


Using the original display as a donor, cut the plug for the ribbon cable and a piece of the board away, and stick it to the new board with thick double-side tape as a sort of "break-out" board to help with assembly. The numbers are backwards on the cut-away board from the actual ribbon cable and socket on the radio main board...makes no sense, but the cross reference chart takes this into consideration. Mark the ribbon cable TOP surfaces and make sure to not get the cable reversed during re-assembly. Use 28ga. insulated wire for the jumpers.

Cross ref for the Winstar Display


When removing the front panel from the sub-chassis, slip the rubber cover off of the main VFO knob, loosen the set screw found below it, and remove the long silver screw from the VFO brake.


When removing the sub-logic board, be sure to unsolder the S-Meter connections to allow the boards to separate.


***UPDATE, 8/31/23***

Another model successfully fitted and installed was purchased from as Yuxian model #
LG3202404BMDWH6N . This is the display I currently use in all 756 upfits. It was fitted and worked fine. It's board dimensions measure 139mm wide x 106mm tall. This is the only model I can still find available that works in these rigs properly. Use 28 ga. insulated wire for jumpers, it's much easier to solder to the pads on the "cut board". 

Attention: Apply +5vdc to the Yuxian display pin 6 (Vdd), ground to pin 7 (Vdd). Measure between pin 8 (Vout) and pin 7 (Vdd, gnd) to check for the presense of -22 to -30 vdc. If nothing, connect Vout to pin 8 on cut board. If negative voltage is present, leave pin 8 connection open. This scenario is an upredictable variable.

I no longer build a 5vdc supply, I power the backlight from 5vdc from the cut board, pins 11 & 12.

This is the wiring matrix between the "cut board" and the Yuxian display:

Cut board = New display

1 = 9
2 = 10
3 = 11
4 = 12
5 = 1
6 = 4
7 = 2 (latch)
8 = 3 (shift)
9 = 13
10 = Frame ground, internally jumpered to pin 7
11 = 7 & 16 (LEDk)
12 = 6 & 15 (LEDa)
13 = 8 via 2k resistor
14 = 5

***UPDATE, TIPS, 2/9/2024***

Tip #1:  I've been meaning to add this tip. Sometimes, depending on the internal menu settings of the radio, the contract will be WAY off and look like a blank screen. I've installed these in radios where the radio screen was totally shot, so there was no way to set the contrast to 50% before starting (something I like to do). There is a contrast pot on the outer board in the sub-chassis, very near where the S-meter terminals solder in place, just behind the wide ribbon cable. If you boot and have only a blank screen,  use a plastic tool, radio ON, turn the pot back and forth to set the contrast as you like. Once all is working, I like to set the menu at 50%, turn the pot for perfect display, and let it go. That way, you'll have a nice range of adjustment from the menu.  NEXT, if you boot, adj the pot and still no font, go to Tip #2...


 Tip #2 : If still no font after tip #1, switch pin 2 & 3 on the display. I've found the mfg sometimes gets latch & shift reversed. Don't know why, but it happens :-)

List of displays used:

- Stanley GMF32024ABTW1X (easiest fit to date)
- Yuxian LG3202404BMDWH6N (from
- Winstar WG320240D-TML-TZ#
- Winstar WG320240D-TMI-TZ#
- APlus Displays: AG320240D-TTI-TZ#- East Rising ERM320240SBS-1
- New Haven NHD-320240WG-BxTGH-VZ#-3VR (dimensional issues on some)
- New Haven NHD-320240WG-ATMI-TZ# (too big)

- Researching a Yuxian SP14N002 CCFL now, the CCFL backlight would make for an easier installation and use the OEM CCFL backlight driver. More on this later...