First of all, what is an "HD box"? Is that a satellite receiver, a cable TV tuner, or what? Do you own it, or does it belong to the cable company or someone you can take it back to for exchange?

Do you mean you are running the HDMI output #1 of the Marantz to the HDMI input #1 of the TV?  You should be; you should be using output #1 from the receiver (if there are two of them), or it could be defaulting back to #1 when you change channels. You should also be using HDMI input #1 on the TV for the same reason.

It sounds like your TV could be defaulting back to a different input when you switch, because your receiver still has the audio, so I would concentrate on the TV inputs and settings first. That is probably where the problem lies; the TV setup.

The TV loses signal momentarily when you switch, and it looks to another input to find a signal automatically; that is my guess. You are seeing snow because it is defaulting to the antenna input of the TV, which I assume has nothing connected; that is my guess. The snow is electrical noise, which the TV may sense as a signal, even though it is a weak one.

To keep the TV from sensing a "signal" on the antenna input you can connect a one-inch cable stub to that connector that is shorted out.

Your " HD box" should be connected to the HDMI input of the receiver.

KrisA wrote:

have my Marantz 6003 hooked up to my HD box vis HDMI cables. Then runnig to my Television via HDMI cable.

The issue I'm having is when I'm watching TV and change the channel from a HD station eg HDFOX to a non HD station, and vice versa. I get white snow image, but with sound. To correct the issue I have to change the imput on the marantz to dvd or vcr and back again. Then it comes through clean. To confuse the issue, if I attemp to change the station while it's in fuzz mode, the HD box will show the station change but I can still hear the same show. Not mention when I do correct the issue and come back to image, it is back to the original station.,, so confusing
I've had the reciever into Marantz 3 times and they say nothing is wrong with it, the HD box is brand new.
Any ideas were my issue could be?

OK so assuming HD Box is a HD Cable TV box first make sure the setup is as follows: Cable coax to HD TV box, then HDMI to Marantz 6003 input, then HDMI out into TV.

Nest, you need to go into your Marantz setup to make sure that your inputs/outputs all match and default to HDMI for your signal chain. It should be that way already, but you need to check.

Also check that your TV is set to automatically adapt to whatever signal it gets- it may right now only be looking for wide-screen content instead of auto-fill, or whatever your particular brand uses to change form HD to SD signals.

If all that fails, you might have something in the cable box that is not setup (something with aspect defaults and how it handles SD to HD signals). This will be in a Service Menu, the codes which you will have to get online for your model. I have a Comcast HD DVR box for instance, and it's pretty easy to check these settings, and I have on occasion had them go screwy for no apparent reason.