Component signal drops with Panasonic SA-HE100 (1 Viewer)

[Paul Quacken]

I was watching CSI: last night in HD and everytime the show switched to one of those flashback type scenes the projector would lose the signal, and start searching for the component signal, which it would re-acquire in about a second. It also happened whenever one of the characters would take a flash picture. What is apparently happening is that whenever the scene goes suddenly from a dark image to a very bright image (such as when a flash went off), the signal would drop. This only happens when I have the STB component video out going through the Panasonic SA-HE100 receiver. Everything works fine if I hook the STB directly to the projector.

Does the SA-HE100 have a known problem with HD component switching? Anybody have any suggestions on how to fix?

STB: Samsung SIR-T351
Receiver: Panasonic SA-HE100
Projector: BenQ PB6200

Thanks, Paul

 

[Mike Robertson]

Paul,

I don't have any answers for you, but I seem to have a similar problem. In my case, whenever there is an abrupt cut (the cuts in Man On Fire for example) or sudden, bright scene, my Sony KP-53HS10 will lose the picture and flash the port and display resolution settings. This happens when I'm using my JVC XV-D723 DVD player in the progressive scan mode connected via the component input or my DISH 921 DVR in the HD mode also connected through the component input. They are both routed through the component inputs of a new JVC RX-8040B receiver. Since I also see an occasional tearing at the very top of a very bright scene I thought it might be a problem with JVC receiver over driving the component video signal. I don't have these problems with either source directly connected to the TV. If that is the problem I was wondering if the component input on my TV has any way to adjust the gain. I doubt if I can do anything with the receiver. Here's hoping that someone else has seen this and can offer us some advice.

 

[Paul Quacken]

I don't experience the dropout problem when I have the STB hooked up directly to my projector. it only seems to happen when I have the component video going through my Panasonic receiver.

Check out this thread:

(sorry, I dont have 15 posts yet, so the system would not allow me to post a URL.)

Apparently the video switching on the component portions of a receiver need to be 30Mhz or higher to effectively switch HD signals. I can't find any specification on the component video switching frequency for the Panasonic SA-HE100, so it could be that the receiver was not built with HD in mind. It's also somewhat of a low end receiver. The only solution I think is to either get a new higher end receiver (or one that specifically says it can handle HD switching), purchase an external switcher, or live with manually moving the component cables from STB to DVD and back. What a drag!

here is an interesting article on component video bandwidth:

(sorry, I dont have 15 posts yet, so the system would not allow me to post a URL.)

Anybody have a better solution?

 

[Mike Robertson]

Paul,

I don't know if my problem is a bandwidth issue with my JVC RX-8040B (neither the manual or the JVC web site give any bandwidth specs on the component inputs) or an over amplification issue of the video signal. I my case, since my amp is new and JVC's tech support was of no help what so ever, I will take it back to Sears and purchase what I hope is a better one. I found a Yamaha RX-V750 at an on-line dealer for $419 plus shipping. Yamaha specs their component inputs at 60MHz so that shouldn't be an issue. Should have it in by the end of the week. I'll let you know if my problem goes away. I was hoping one of the more knowledgeable members of the forum would provide a more educated response to what seems to be a similar problem.

 

[Bob McElfresh]

You would really rather have 90 Mhz bandwidth.

Here is the issue: you want the bandwidth of your cable & switcher to be 3-4 times the maximum frequency you intend to shove through it.

If you use a cable/switcher without this, things can appear fine - as long as the frequencies change slowly. But if the signals suddenly change (like a movie/show with flash-photography) the signals will not flow smoothly unless the cable/switcher was designed for 3X or 4X the maximum frequency.

(Think of a water pipe rated for 45 psi and your static water pressure is only 30. Should be fine - right? But what happens if you run the water and suddenly shut the flow off? The water will over-pressure for a short time and reach 50/60/70 psi. While video signals dont build up pressure, there is a similar behavior when the signals suddenly change.)

Here are some upper-limit frequencies:

Component Video (480i) : 4 Mhz
Progressive Video (480p): 13 Mhz
HD Video (720p & 1080i): 35 Mhz

My guess is you are running HD video through a reciever designed for ordinary component video. Usually, it works fine. But get a sudden burst of light in the scene and the signals reflect/ghost inside the reciever and when the mess finally comes out - your projector does not know what to do with the garbage. So it looses video sync.

Try to get a reciever with 90-110 Mhz bandwidth for the video connections. Or consider a external 4:1 HD video switch box as described in this thread: Inexpensive HD Video switching

Hope this helps.

 

[MikeMe]

Bob,

I really have to disagree with you on this. When a signal is rated at 35 Mhz (for HDTV), it means that the bandwidth NEVER exceeds that value. A device with 60Mhz bandwidth is just as good as 90 Mhz bandwidth for HDTV. The only spec that matters is what the loss is at 30 Mhz and below.

The situation Paul is describing sounds much more like a low frequency problem. Changes in scene brightness have nothing to do with the high frequencies in the signal.

 

[Paul Quacken]

I received this reply from videostorm in response to a similar Posting I put on AVSforum. This seems to be a different, but also plausible explanation for my problem. Anybody have any comments on this?

All,

I know what is causing these problems. The key words are
"losing sync when scene transitions (bright/dark) occur". This is due
to AC coupling in either the STB output or the component video switch box. Some monitors/projectors out there (

 

[MikeMe]

I agree with that explaination. AC coupled signals can have poor low frequency response if the caps used are not large enouph. DC coupled signals have perfect low frequency response.

 

[Mike Robertson]

Well, I originally thought it was a bandwidth issue. Now I don't know. My Yamaha RX V750 arrived today and I changed it out with the JVC. I ran the Man On Fire dvd and had zero problems. I connected my Dish 921 and ran it in the HD mode and again, no problems. So, I don't know if it was bandwidth or how the receivers' component outputs couple to the TV. If anyone knows how the component input design of JVC RX-8040B differs from the Yamaha RX V750, maybe they could shed some light on this.