Icom IC756 MK1, another display repair :)

Icom IC 756  first model, and first batch of these transceivers are prone to display fault-horizontal
lines on display....
Only reliable solution for this problem is to change whole display...sadly suitable 4.7-5 inch display for repair in these days is hard to find....winstar models WG320240D are hard to find, Stanley GMF32024ABTW1x or APlus AG320240D-TTI-TZ# either....

On internet...or aliexpres, ebay you can find many variations but they are nor cheap at all.
After many hours of research I find some solutions which is , for skilled or less skilled electronicians
relatively easy reproducible ...

You need old display for flat connector assy.

Source of problem....losy or contactless flat ribbon cable....

 You must dismantle front panel and many other parts of radio...:(

 Backlight mod...remove HV transformer and one inductor-as per schematic

 Backlight  connection, for led backlight....

 Some drilling and cutting to fit the  new display are necessary ...depends of display dimensions etc...

 Chinese display...good quality, and best result, viewing angle isn`t ideal but...acceptable

 Bad contrast...problem wich i have sorted in a harder way :(....You must READ display PDF for proper connections (struggled with this problem minimum one week  HI!)

 DEM320240E dispay with onboard controller-i bought this only for test...display is ok but china display is better

 Removed flat connector ...

 Removed MCU and preparing for direct connection with radio...

 Same result-bad contrast...resolved latter ;)

Dem320240E have internal negative source for contrast driving....good solution, but internal contrast is better....or not?...When using internal contrast circuit you will be able to adjust contrast via radio`s menu...and this operation is impossible  when using display internal contrast  circuit....

Basically you can use any 4.7-5 inch display for this mod, only display physical dimension  is important.

Original Sanyo displays  for Icom IC756 do not have any mcu control or contrast negative voltage source on board, all these circuits are on transceiver motherboard.

So, we need Display without mcu on it, and even without negative voltage source for contrast circuit....

But today displays are 5.7inch (this is too big, don´t even try to mount....BIG), or you can to buy 4.7 or so called 5 inch displays with onboard mcu...with 20 pin or whatever pin connections...but final question is: can we use this type displays for our transceiver?Answer is: YES...they are in 90% fine for IC756...watch for dimension!

All displays with mcu on board use some kind same mcu chips and they variants are
S1D13700
RA8835
etc...
we simply don´t need them!...best solution is to desolder mcu from board, don´t use here hot air
desoldering tools since we have on other side of display board backlight spreader made of plastics...
or take care during dosoldering...

This is the list of pins what we need to connect to our radio.

Use  thin enameled cooper wire...or other wire...yes, is tricky to connect all this pins but not impossible.

 You can buy this display on TME...stock is limited but...
For display from china pls mail me...like I said, this is good display but you need to mod some pins and jumpers on display ...in stock configuration they don`t work good ....

73 de YU5MOL!