Svideo and ADB ports use the same pinout/connector, those on the motherboard itself are ADB, whilst the 840AV (and most AV Macs) have a small breakout box with Svideo, composite, audio in/out. Perhaps your board didn't come with this part? You could probably make your own if you had the correct pinouts.
Interestingly, if you ever need an ADB cable to connect a keyboard or mouse, an svideo cable will work just fine
Looking forward to your 840AV case mod! You could try for an 840AV pizza box
JB
Interestingly, if you ever need an ADB cable to connect a keyboard or mouse, an svideo cable will work just fine
Looking forward to your 840AV case mod! You could try for an 840AV pizza box
JB