Leonard Caillouet wrote:
OK, maybe some of you can see what I am missing or know something that I
don't that can shed some light on this one. We have a client that has had
this Yamaha receiver and Mits HD ready set for a few years and just switched
to Cox HD cable. The receiver has been working fine, switching both
component and composite signals into the set. Hooking up the SA box through
the Yam (component signal) gives a pix in which the whites are "blown out"
or "crushed" like the video is too intense. Black levels look normal. The
effect is like looking at video that is not properly terminated at 75 ohms.
Other sources besides the SA box look fine using the same inputs on the Yam
and Mits. Here is the catch. Hook the SA box up to the set directly and it
looks fine. OK, so the Yam is the problem, right? Well, pulled it to the
shop, assumed it might have a bad ground or something and checked, re-seated
everthing in the vicinity of the video board. Threw every kind of source at
it that I could, and the input and output looked identical, pix looks fine
with every source 480i to 1080i on every one of 4 different technology
displays.

Put it back in the system assuming that we had missed something or maybe a
bad cable or something and the same thing happened. I have not looked at
the output of the SA box yet, since we do not have Cox at the shop and can't
get it. Guess I will be hauling a scope out to the site. Maybe someone
will come up with some ideas before I go.

The Yamaha seems to be a very straightforward buffered switch with about
60Mhz bandwidth. I could not detect any degradation in signals passed
through it and I confirmed it terminates at 75 ohms. Maybe the output of
the box is really hot and the Yamaha is not tolerant and clipping the
signal? Looks fine going directly into the set, however.

Any ideas?

Leonard

We came across some 'prosumer' gear at work that did not have correct
output termination which caused some aggavation when trying to connect
it in. In your case I'd take the source video into a BNC 'T' connector
into the input of your scope and then connect the terminator on the
other leg of the 'T'. If everyone is 'playing by the rules', the level
should drop by 6 dB and be 700mV without sync, 1 V with sync.

Good luck sorting it out.
GG