CM7000 converter box missing S/P DIF? circuit that feeds the "Not Used" RCA jack

[wa2ise]

Popped the lid off my CM7000, and "ohmed" out the traces in the area of the missing parts that feed the "Not Used" black RCA jack. The below diagram appears to be what is missing. Of course I don't know what the values of the missing resistors and caps are, but as SPDIF levels are around 1/2 to 1 V at 75 ohm impedance, and the feed from the chip is probably 0 to 3V, and with the two emitter followers in series, RD61 is probably 150 ohms, and RD62 is probably 150 ohms. CD29 is probably 0.1uF, RD60 is probably 1K, and RA7 around 100 ohms. CD26 is a bypass of the 5V supply. There's a space for RPR1 near the RCA jack, but I don't know why it's there, and I think I can safely ignore it. CD30 is probably a roll off cap of something like 50pF, you probably could ignore it. QD10 is a PNP, and QD09 an NPN, any general purpose ones should do.



This all assumes! that the SPDIF from the STx7707 is in fact active, and not been turned off via SW or such. If I had a scope handy, I could easily tell.

Standard disclaimers and YMMV. I haven't tried to build any of this yet...