BigPotAD8367 VHS Setup

NOTE: WARNING: It has recently come to light that crosshatch is most likely caused by too great a load (too low of an impedance) being connected to the tap point and causing the head amp to clip. The AD8367 board is internally terminated at 200 ohms, it cannot be changed, which is too low in most cases.

This page exists for historical purposes only.

• CARD: White PCIe CX23883 card (pic to identify: https://github.com/tandersn/cxadc-hw-mod/blob/main/X_Pictures/cxcard4ad8367/stockCXwhite.jpg)

• AMP: Big Pot AD8367 board (pic to identify: https://raw.githubusercontent.com/tandersn/cxadc-hw-mod/main/X_Pictures/BigPotAD8367/stock_big_pot_AD8367.PNG)

• FILTER: Uses filter components built into CX card

• POWER: 3x AAA battery holder with switch: https://raw.githubusercontent.com/tandersn/cxadc-hw-mod/main/X_Pictures/opa657/3aa.jpg

• MISC: resistors, capacitors, small project box, SMA/BNC/RCA adapters and connectors, small zip ties, double sided foam tape

• Purchase link: https://www.aliexpress.us/item/2251832840614311.html

With this setup, and the mods detailed in the pages to the right, i've achieved very good results. PLEASE READ through all the pages before starting, as some of the optional mods negate some of the steps of other mods.

The pros of this setup, and the reasons i put it first are:

• 5v single supply voltage (easy power configuration)
• Capacitor built in so no capacitor needed on tap points
• Wide compatibility and eas of use

The cons are:

• You MUST use a very short cable from the VCR/LD player to the amp
• On my big pot AD8367 boards, the gain knob is backwards
• The 200 ohm load requirement of the AD8367 amps mean you have accommodate it in some way, here we put a 150 ohm resistor after the amp, which limits the overall gain achievable (but it still seems sufficient)
• The AD8367 has a "self centering" function built in, it doesn't seem to work quite right, so this is why the output capacitor is required. In the essence of "less is more", i'd rather have less overall components in the chain.

The last two bullets apply to ALL AD8367 boards.

As mentioned earlier, this setup performs nicely:

Connecting to the card:

• Use an S-Video to BNC breakout cable.
• Use an RCA to BNC adapter, and remove C31 from the CX card if needed.
• Do the BNC direct wire mod, and do the BNC mod.

Directions for this mod:

• Mod card for BNC (optional but recommended): https://github.com/tandersn/cxadc-hw-mod/wiki/CX-CARD:--Replace-RCA-jack-with-BNC-jack
• Mod AD8367 Big Pot board: https://github.com/tandersn/cxadc-hw-mod/wiki/AD8367bigpot-amp-board-modification

Connection diagram / layout: