A500 rca cable.Will this work?

[motrucker]

As tone007 stated, this will work for audio but not very well for video. You will only get B&W from the A500's RCA video out.
What happened to your cable to hook up the cm8833 to your A500? If it's gone they are not impossible to find - and would give you MUCH better video.

[motrucker]

You don't need the 520 then. Just use the "RGB" cable for video and the RCA for sound and you have it!