AC3B T-VWV143 / T-VNP411A (GXX1135)

This short document is about the T-VWV143 / T-VNP411A AC3RF out mod board I have came across. I found this board (box) in a Japanese Pioneer LD player.

The board itself is shown in Fig. 2., Fig. 3. (top views) and Fig. 4., Fig. 5. (bottom views).

Although the type numbering of the board (VWV143 / VNP411A) looks so Pioneerish (and the PCB itself could be Sonyish :-) ), i would guess it was a third party extension board sold as a kit (by who? - i cannot recognize any logo, "B@" / "とど" and the "工" on the copper box are unknown to me).
Later it turned out that's it's actually a real Pioneer upgrade kit: GXX1135 (thanks to Julien@lddb).
It is housed in a nice copper box (Fig. 1.), and what is interesting that it has a "Video" input. Actually, the RF video signal (or even the unfiltered raw RF signal) goes there. There are 3 connectors on the board:

• CN1 (left, white): 3-pins for the audio RF
  (pin 1: RF-IN, pin 2-3: GND)
• CN2 (top, white): 6-pins for power/mute signal/output RF signal
  (pin 1: AC-3 RF OUT, pin 2: GND, pin 3: MUTE, pin 4: +5V, pin 5: GND, pin 6: -5V)
• CN3 (top, red): 3-pins for the video RF
  (pin 1: VIDEO, pin 2-3: GND)

The main task of the board is of course the usual: amplify the audio RF, and switch it on/off according to the "Mute" state of the player. Remains of soldering flux suggest that some of the resistors were desoldered, probably the board is "configurable" by removing resistors (cutting connections), but that's just a guess. Looks like R8, R9, R10 and R16 were removed by the technician installing the board, and R33 seems to be unpopulated by design. I did not trace those yet, so i am not sure about their functions.

In this configuration, the board works (yes, actually it works perfectly!) even when the video RF input is not connected. The only difference i could observe, that when the video RF is connected, the max. peak-to-peak voltage of the AC-3 RF out signal drops slightly, so the output is attenuated a bit. Maybe, then the function of the video RF input is to control the amplification of the audio RF signal. Again, just a guess.

Anyway, it looks professional, and the box is quite fancy too (see Fig. 6. and Fig. 7.).

In the Pioneer HLD-1000 player, it is mounted behind the front panel on the left side (when looking from the front). Two small holes were drilled there and screws hold the box in place (see Fig. 8.). The output is wired to the second composite video out (with the original 75 ohm resistor for the video out removed).


Do you know more about this one?
Please contact me then, thank you very much!