Attention:
- It is easy to install, but there are some things to pay attention to.
- It is a handmade item. Some parts are purely artificially soldered, and PCB has flux residues. Users who do not know how to deal with them should purchase with caution.
- It requires users to have a certain amount of hands-on ability.
- When using your battery, please connect the positive and negative poles correctly. There are positive and negative labels next to the battery socket. When charging, please use a computer USB connection or a 5V charger.

Recommendations for Using Bluetooth:
- The use of Bluetooth is affected by the environment. If there is a continuation of keystrokes, there may be signal interference or poor signal.
- Some computers may interfere with Bluetooth when connecting to multiple devices. You can try to connect only one keyboard to see if it works normally.
- Connect other devices to find the ones that may interfere. For example, AirPods on some computers may interfere with the keyboard.
- Other instructions can be found in the help document, Bluetooth keyboard signal optimization related parts.

Supported Model List:
PD-KB400W: for HHKB Professional 2 White with lettering regular version
PD-KB400WN: for HHKB Professional 2 White no Lettering regular edition
PD-KB400WS: for HHKB Professional 2 White lettering Type-S silent version
PD-KB400WNS: for HHKB Professional 2 White no lettering Type-S silent
PD-KB400B: for HHKB Professional 2 Black with lettering regular version
PD-KB400BN: for HHKB Professional 2 Black no lettering regular edition

Main Features:
- The whole modification does not require welding. Just screw the screw and pull out the cable to change the main control, which is very easy.
- USB and Bluetooth 4.0 modes. You can switch between wired and bluetooth when plugged in, and charge through the USB data interface.
- Under USB, it supports full-key no-rush (can be switched by left and right Shift+N); under Bluetooth, it supports any 6-button no-rush.
- All key positions support customization. The firmware function is based on tmk, and the [ydkb.io] graphical tool is used, which is simple and easy to understand.
- Qmk-based firmware that supports VIA is also available. See [via.ydkb.io]
- Automatic energy saving, extremely fast wake-up. The original Lock Mode prevents the buttons in the bag from being pressed and consumes power, making it easy to carry.
- Most new systems support power display.
- USB HUB (USB2.0, only available in wired mode), mainly for aesthetics. There are three in total, two external and one internal.
- The main control comes with charging and LED3 indicator. The front also supports the installation of three indicator lights (LED1, 2, and 3).

Package Included:
- 1 x Controller Board
- 3 x LED Lights

Note:
- Battery is not included. 3.7V lithium battery is recommended. Battery size is within 6.6x42x80mm/0.3x1.7x3.1".
- This is not a keyboard, just the master control, you need to bring your own keyboard for HHKB.
- The pictures below are for reference only. Please refer to the actual product.

Charging:
The original data cable interface can be used for charging, and the charging will start when a cable is plugged in.

Installation Notes:
Attention: It doesn't matter if you don't use internal USB and three LED lights, and you don't have to use them.
1. Unscrew the three screws on the back of your keyboard, and the keyboard can be opened, but there are still cables connected, and the upper and lower parts cannot be completely separated.
2. Unscrew the screw in the upper right corner of the original main control, the main control can be taken out, and the upper and lower parts can be separated.
3. Remove the cable, as shown in the figure below, the key is to use a little force, it is not so fragile. Attention: Pull with a little force, and you can shake it slightly from side to side while pulling.