Upgrade Panasonic UB820 and UB420

BD player Mod. 2020. 8. 6. 11:25


Last week, I had chance to look at the inside of the Panasonic UB820 UHD player, 

As expected, I confirmed that the Panasonic UB820 is based on the Panasonic UB420, just adding analog DAC audio.

UB420 and UB820 are almost identical in structure .

Only differences are an analog audio output and  front panel display.

Unfortunately, the analog audio output section of  UB820 is not at the level for full-fledged music listening.


Once the power source is also generated from a single 12V DC power supply, the DAC chip and the IC chips are 
very simple general purpose chips. (In my personal opinion, this analog audio section is much worse than the Oppo 203 circuit.)


On the other hand, it can be said that the UB9000 has both structure and performance as a high-end player.


Here is upgrade mod work

1. Change  the rectifying capacitor to 82uF/400V ( temperature  105 degrees )
Use audio grade class capacitors from Nichicon, Japan to improve performance.

2. Using  two  Nichicon KW series of audio grade capacitors , increase  4700uF+ 3300uF at the end of Power supply section and  reduce high frequency impedance by adding 1uF/63V, 0.1uF/100V film capacitors( Germany Wima ) in parallel. 

3. Attaching a large heat sink, one on each side, since  the AV processor IC generates a great deal of heat

4. Replace 25 Mhz crystal next to AV processor with 2 PPM class TCXO


After all mod, Your UB820 or UB420’s performnce will be nearly up to that of UB9000.

Befor uograe work of UB420


power supply upgrae 
TCXO mod . use 1.8V 25Mhz TCXO 

HR PCM/DOP SPDIF board for OPPO203/103(D)

BD player Mod. 2020. 8. 3. 09:41

This is a concept that replaces the existing OPPO 203 analog audio board. It now functions like a Vanity HD board that has been discontinued.

  It is different to support only 2-channel stereo. The price has also been lowered from 899$ to about 370$.

  In order to do a DOP (DSD over PCM) function, there was no other choice execpt using a USB port on notebook computer .

  But the notebook computer had a lot of EMI/EMC noise, so it has a lot of problems using it as a source device.

  Mounting this HR PCM/DOP SPDIF board on OPPO203 makes it very easy to use and delivers pure music data.


Currently it is only developed for OPPO 203, but it will soon be developed for using in Oppo 103 (D) as well.



  1. Stereo 2-channel only

  2. 192KHz/24bit PCM and DSD128

( The board itself can handle 384Khz/36bit PCM, DSD256, but OPPO 203 firmware limit its functionality )


3. Using proprietary high-precision clock.


4. Using an optical coupler to separate the main board ground to prevent noise inflow


5. Gold-plated unbalanced terminals (AEB/EBU type balanced 3 pin terminals can also be mounted)

6. Use a separate independent power supply from the linear power supply (existing analog DAC power supply can also be used)


7. High-precision matching transformer at the output stage