Yaesu Yaesu FT-4XR Walkie Talkie Charger

Update 2024-05-24:
To improve charging voltage, the wiring of the HX6048's BAT pin was updated. The output charging first passes through the battery and then returns to the BAT pin.
Update 2024-03-05



: The Schottky diode parameters were
modified from SS34 to MBRX140. The resistor package was changed from 0805 to 0603.
The positive and negative terminals of the output were optimized. The main circuit board layout was significantly changed, including chip and connector placement. The charging chip is now closer to the positive terminal.
Poor power supply or power bank ripple can cause the HX6048 to overheat, so the heat dissipation layout was improved.
The two inner right angles of the upper card frame PCB were changed to rounded arcs.
The CH224K was changed from single resistor analog voltage control of Type-C voltage to 3 digital voltage control of Type-C voltage. One resistor was removed. See the Schwarz text for details.
A 220uf/16V tantalum capacitor was added. To reduce height, a non-standard stamp hole recessed plate was used for soldering (unverified).



-----
 
The CH224K was used to trick the 12V of the Type-C port into powering the module. This is a Yaesu FT-4XR walkie-talkie charger, using the schematic of the Baofeng UV-5R charging dock.
The basic principle is to use a 12V source (either Type-C or DC) to power an 8.4V charging management chip, which then charges the walkie-talkie's two 4.2V*2=8.4V lithium batteries.
Improvements could be made by changing the spacing of the surrounding solder pads and replacing the surrounding PCB connector posts with 2.54mm pitch pin headers
, which would make soldering much easier. The assembly is quite complicated.
The spring contacts use antenna connectors, purchased from LCSC (BAT WIRELESS) BW0039BG-L3.0W2.0H1.5) https://item.szlcsc.com/2970169.html.
 
The soldering is complete; only
 
the Type-C contacts are used to extract 12V. The DC connector is not soldered as it's too bulky.
 
A green light indicates a fully charged battery,
 
 
while a red light indicates charging.