Tuesday, August 29, 2023

Another IC-756 Display Replacement

 This is another Icom 756 display repleacement using the Yuxian model # LG3202404BMDWH6N display. This is the first unit Ive done without building a separate outboard 5vdc power supply for the LED back light. After extensive testing, I determined the 5vdc regulator on the main board is more than ample to supply the new LED backlight. I go in the main menu and turn off the CCFL backlight by setting it to 0%. I also DO NOT feed the contrast voltage from the main board to the new display, these have internal thermal compensation for contrast that is more than adequate. Click "756 Display" in the menu at the top of the page to see the latest in installation notes, as I have certainly gone through a lot of different displays over the last few years. Here's a few pics and more notes...

I LOVE these radios with the blue display!!

 Front panel off, about to disassemble it for the fitment of the new Yuxian display.


Above is the new display, ready for fitment into the subframe. Size is close to original...actually, the screen is the same, but the pc board and frame are slightly larger. 


Below is a pic of the 1st board that has to be removed from the head unit. Some things are soldered between layers, so you have to take your time and be patient. 

Above, you can see the display fitted into the sheet metal subframe. I use a dremel tool and cut-off disc to trim sheet metal from the subframe. I have it marked at the top of the pic above, near me thumb, where I'll scribe a line and cut away this amount. . You can see, two photos below, where I've trimmed the metal away and mounted the display assembly. 

 In the photo below, you see where I cut a piece from the bad original display, and use it to attach the ribbon cable and interconnect to the new display.


Above, you see the new display mounted into the sub-frame, awaiting wiring. Below, I have installed the cut section from the old board and wired it to the new display unit. In this way, the original ribbon cable from the main unit to the head is still used without modification. 


Above and below, I'm testing the backlight with external 5vdc power. At this time I"ll peel away the protective clear covering and begin to reassemble the head unit. 


The last few pics show the display in testing, head unit reattached to the main unit, and in the process of setting the contract level from the main menu. The level of blue is adjustable with contract. The display has about a 10 minute warmup period, after which the display contract is stable and needs no further adjustment. The displays are more directional that the original, so you'll adjust the contrast for your taste, depending on the viewing angle you usually have for the rig. 



Friday, August 4, 2023

Icom IC-7000, Won't power up...

 This was an Icom IC-7000 that wouldn't power up. You can press the power "on", and almost immediately hear a "click" from within. This is caused by the processor shutting the rig back down when certain voltage rails aren't properly detected. This is a very common problem with these as they age. Almost always caused by bad electrolytic capacitors. I've found this to be with C501 or C502 in the head unit, or both. The larger value caps are typically the culprits. Here is a link to a PDF written by another ham on the same topic. These aren't difficult to repair, should you run across one with this problem. I didn't take pics of the task, since the .PDF adequately documents it. The link to the pdf is: