CX CARD: Modify PCIe CX card to work with OPA657
It goes without saying, but i'm going to say it anyway, you should double check each connection after each mod, with your multimeter. It can save you trouble later...
This modification procedure uses 0603 SMD components, for alternates using "big" components, see other modification pages.
This OPA657 setup works best with 50 ohm load / termination. Note that this is NOT the optimal value for use with AD8367 boards. **This mod is for use with OPA657 only.
Picture of stock card for reference: https://raw.githubusercontent.com/tandersn/cxadc-hw-mod/main/X_Pictures/cxcard4ad8367/stockCXwhite.jpg
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It's easier to do the mods if you remove the bracket temporarily, so do that first.
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Remove the crystal Y1 (in GREEN) and replace with the 40mhz crystal product listed on main page.
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If using a BNC or SMA to RCA adapter: https://github.com/tandersn/cxadc-hw-mod/blob/main/X_Pictures/sma2rca.jpg or https://github.com/tandersn/cxadc-hw-mod/blob/main/X_Pictures/bnc2rca.png , modify vmux 1 (RCA) input to remove components annotated in RED: C59, C31, L8, R24
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Solder a "0" ohm resistor in position L8
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Solder a "50" ohm resistor in position R24
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Leave C59 unpopulated
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Leave C31 unpopulated
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If using an SVIDEO to BNC breakout dongle: https://github.com/tandersn/cxadc-hw-mod/blob/main/X_Pictures/svid2bnc.jpeg modify vmux 2 (svideo) input to remove components annotated in BLUE: C61, L3, R1
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Solder a "0" ohm resistor in position L3
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Solder a "50" ohm resistor in position R2
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Leave C61 unpopulated
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Personally, i prefer to remove the RCA jack and mount a BNC jack in its place (in conjunction with the vmux 1 mod from above) https://github.com/tandersn/cxadc-hw-mod/wiki/CX-CARD:--Replace-RCA-jack-with-BNC-jack
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there is no detriment to modifying both inputs, other than you won't be able to use the card for regular CVBS capture.
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once the you are done, replace the bracket.
