My Samsung TV is connected to Yamaha RX-V371 amp. At least twice every evening the picture disappears with a message requesting me to check cables or source.

SOURCE: connecting LG DVD recorder to cable box and HGTV digitally

Two things come to mind: copy protection and resolution settings.
The TV may not allow copy protected material to come from your LG, or the sampling frequency may be unacceptable. On page 15 of the manual it talks about 96kHz and 48kHz frequency settings. The third thing to check is the vertical resolution using the RES button on the front panel. SDTV is 480, and HDTV is anything above that. Using the HDMI is supposed to allow upconvert to 1080i max if your set can use that resolution.
tom

SOURCE: How to eliminate error screen:"your tv does not allow display of this program through the dvi input source. please chose another tv input source."

"cable box to tv is hdmi cable"

Everything I've read on the web says cable box to tv connection must also use component (rgb) cables. The error is coming from the cable box (STB). All the Scientific Atlanta (SA) cable boxes seem have this Digital Rights Management (DRM) bug and the only way to be totally rid of the error is to replace the digital connection from box to the TV with an analog connection.

SOURCE: sharp model lc19sb25u sound and no picture screen

Part called main unit failed and require replacement. part number duntke352fm02.

SOURCE: Yamaha RX-V365 unable to receive 5.1 audio from TV with HDMI

If you're expecting multichannel sound FROM THE TV instead of from the source you're watching, it's not gonna happen. TV's are notoriously poor sound sources. This one is no different.

Multichannel TV-related audio is best found at its source - cable / sat / dvd / bd....

I run video-related audio from my video sources directly to my TV and their audio directly to my receiver. Specialization yields best results.

I'd recommend skipping the Receiver for video, too, as it adds a lot of opportunity for HDMI-related incompatibilities and sound syncing problems. The more interconnects in the path, the more distorted it will become and the more opportunities for problems. Plus you can bypass the receiver and listen to lo-fi programming like news and weather through the TV's speakers if you like. Save a buck on electricity.

Just curious, which HDMI on the receiver is connected to your TV? Input or Output?

This note is on Page 11 of the manual:

Audio signals input at the HDMI jack are not output from any speaker terminals but output from the connected video monitor. To enjoy the sound from speakers connected to this unit,
-- make an analog or digital connection besides the HDMI connection (see page 13).
-- mute the volume on the connected video monitor

================
"Check SP cable." -- The unit is perceiving a short circuit. Are your speaker impedances sufficiently high? Disconnect the Front Right speaker and try raising the volume again. The speaker may be blown or the cable shorting.

SOURCE: DVD input to HDMI 1 have no signal (displayed by

Some Onkyo receivers are known to have HDMI issues (it has faulty capacitors). The first thing to do is to reset the receiver.
To reset the AV receiver to its factory defaults, turn it on and, while holding down the [VCR/DVR] button, press the [ON/STANDBY] button (see page 96 of the manual).

If that doesn't work it will have to go in for repair to have the HDMI board replaced.