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A few months ago, I took advantage of the weakening yen to purchase a Japanese-made Yaesu DX10. Initially, everything was fine, but then I discovered that there were many bright spots and dead pixels on the screen, which was very frustrating. The cost of official after-sales repair was close to 800 yuan, which is not worth it for a 5-inch 800x480 resistive screen. Furthermore, considering that the original screen quality was already like this, replacing it might not make much difference. I also heard that expanding the frequency on Japanese models is relatively simple, so I decided to disassemble and study it first, while also taking a look at its internal structure.
The disassembly video has been uploaded to Bilibili. Click here to access it:https://www.bilibili.com/video/BV1iii7efEgC/
1. Enclosure part
The casing consists of two layers: the outer layer is a black iron shell, and the inner layer is a silver-colored shielding cover. Both the top and bottom have this structure. The screws on the outer layer are black, while those on the inner layer are silver. A friend had previously mentioned that the screws were "fragile," so it's best to choose the correct screwdriver head to avoid slippage.
2. Lower Layer: Signal Processing Section (including spread spectrum location)
The lower half of the machine, which includes the layer where filters can be installed, is responsible for signal processing and other functions. Various chips are also located on this side.
There is an empty space in the lower-left corner of the circuit board, which can be used to install a 300Hz CW filter. It is said that it has good performance and costs around 1000 yuan; however, I don't use CW or plan to add one. The bottom-right corner of the board contains the machine's CPU, model R5F61645FPV, which is a 32-bit processor from Renesas with a clock frequency of 50MHz. On the right side, there is an R5F56519ADFP, also from Renesas, which is a 32-bit microcontroller using the RXv2 kernel with a maximum clock frequency of 120MHz.
Since the CPU is here, the frequency extension point should also be nearby, specifically in the lower right corner of the CPU. There's a row of contacts there. Regardless of which version of the machine you have, solder together the JP6 contact on the far right, and then reset the machine to enable frequency extension:
The TMS320C6746, a high-performance 32-bit DSP chip from Texas Instruments, is located in the upper right corner of the machine. It has a floating-point processing frequency of 456MHz and is used for audio signal processing. The actual operating frequency is 368.64MHz. In addition to its ability to implement functions such as SHIFT/WIDTH/NOTCH/APF, the NB (Noise Blanking) and DNR (Dynamic Noise Reduction) noise reduction features are also implemented by this DSP chip:
Beneath the large shielding on the left side are the FPGA and two ADCs. The FPGA is from the Xilinx ARTIX-7 series, and the ADCs are AZ62P45 with a 14-bit resolution (same as the FT710 solution). Removing the shielding is difficult, so it has not been removed. The following image is taken from the official catalog:
3. Upper Layer: RF Amplifier Section
Turning the machine over reveals a large circuit board that integrates functions such as amplification, low-pass filtering, and tuning.
In the lower-left corner, there is a speaker; this parameter has not been studied. To the left of the speaker is the amplifier section, which uses the RD70HUP2 tube as an amplifier, a single VHF amplifier chip. The DX10 has both 50MHz and 70MHz transmission capabilities, while the low-frequency part uses a matching coupling circuit. What's interesting is that the primary transformer does not use wire for winding, but instead a circuit board:
Above the amplifier is a low-pass filter, and in the upper right corner of the low-pass filter is a power standing wave detection circuit:
The right side was occupied by the "Tian Dao" section:
4. Front section
The front of the device consists of a plastic panel on the outside and a metal frame inside, which is used to secure the screen and control board. When disassembling, first remove the two separate encoder boards. Also, note that all knobs except the large knob (volume, function, etc.) can be directly pulled out. These are then secured with flat hexagonal nuts on the outer casing, which can be removed using a flat-head screwdriver or an open-ended wrench. To disassemble further, first remove the outer rubber cover from the large and ring knobs. You can use your fingers or a small rod to help remove them. The large knob has one internal hex screw that can be loosened and then removed directly. Finally, remove the screws from the ring knob. Note that the mechanism for adjusting the resistance of the large knob is complex; you can use a string to connect the components after disassembly.
The front panel has two circuit boards. One handles the signals from various buttons, knobs, and the display of the indicator lights on the control panel. The other board is responsible for communication with the main unit and also controls the screen. It uses the R7S721001VC processor from Renesas, which contains a Cortex-A9 core with a 400MHz clock speed, used for controlling the machine and displaying information on the screen.
The screen is manufactured by a British company – but it also has "Made in China" printed on it. The biggest drawback of this machine is the screen, which is a low-resolution LCD panel with a resolution of only 480p. As a result, there are several dead pixels and bright spots, as well as some minor dust ingress between the internal and external screens. Replacement costs 792 yuan, which is quite frustrating.
Therefore, I will share my experience and tutorial on modifying the DX10 screen in the future. Currently, it is still under testing, but overall, it can be done for less than 100 yuan (RMB).
The dead pixels on the screen are difficult to distinguish because they are not easily visible when photographed. I have included two clear examples: The first shows a series of consecutive dead pixels, with one pixel displaying an inverted color while the others remain normal.
The second chapter was particularly striking because of the black background, which made the details stand out.
I won't list all the remaining issues at the bottom, but in my conversations with other enthusiasts, their machines didn't seem to have this problem. Perhaps it was just bad luck on my part.
That concludes this section of the DX10 disassembly. Updates on subsequent repairs and communication will continue, and I would appreciate any corrections or inaccuracies pointed out by experienced users. Comments and feedback are also welcome. This is BG6HFD, signing off with 73!
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