My Harmon Kardon AVR 430 will not play sound and displays "unlock" when optical is selected

SOURCE: harmon kardon avr 25 II

hey i also had this problem, i don't know the name of these but they are basically plugs that you have to block output from the front rear and center speakers of the white/red cables... sry for bad description but its on the left side when looking at the back of the receiver, while all of the other speaker wires should be hooked up to the right with the twisting knobs... it took me forever to find this out but yeah it was a simple fix

SOURCE: cannot get dts from my Harmon Kardon AVR 300 via my Blue Ray

I'm not sure if this solution is still necessary however:

I own a H/K AVR300 and have a PS3 hooked up via HDMI to the TV and Optical TOSLink to the receiver. I have no troubles selecting between DD 5.1 and DTS 5.1. I can even select trueHD whatever format but I can't detect an audible difference, I think that mode might be downgraded back to regular DD5.1...

Hope this helps...

SOURCE: Audio problems using a Playstation 3

First try ensuring that "OPT 1, 2, or 3" function is selected depending which one you are using on the H/K 146 (see manual for selection instructions). Next please ensure that the PS3 audio out set to "optical" (Settings/sound settings/audio output settings/digital out+DD 5.1). That should help.