I have been following this thread for a while now, and I think the Mike has been doing a great job. However, after just building a JP1 interface I have to believe that there is a easier way to accomplish what we want (i.e. using the 7 pin header). Here are a few of my thoughts that I hope someone here can shed some light on:

1. a search on google for ohsung turns up this:
http://www.ohsungec.com/

Ohsung is the parent company for home theater master (notice that Ohsung's US office has the same address as home theater master). They also show the mx-500 as a product. Maybe (ok, big maybe!) we could get the datasheet for the osh1002p chip? Problem solved.

2. Ok, so we can't get the datasheet. I assume that the mx-700 uses the same chip (the osh1002p) as the mx-500. Does the mx-700 have this same 7 pin header? If not, does the the serial connector on the mx-700 use the same pins on the osh1002p? There will probably be a rs-232 level converter between the serial connector and the osh1002p. If this is the case, then we could just reverse engineer the mx-700 serial protocol and add our own level shifter.

Does anyone with a mx-700 want to open it up?

Thanks,
Derek