Video cable questions - can anyone help?

[sailgb19]

I posted these questions last week, but so far have had no replies. Can anyone help?

A couple of months ago a power surge "fried" some of the inputs on my TV. As a result I get a picture with bright whites from my VCR plugged into one composite input, and for my DVD I only get a good picture if I plug in a composite and S-video cable at the same time (each one alone doesn't get a good picture!). (The local TV repair guy claimed to have fixed it twice, but it is still not working properly). I recently purchased a receiver that allows me to route all of the cables into it and just have one cable to the TV. The installation is such that I would need a long video cable to get from the receiver to the TV. This is only a temporary arrangement and I do not know if the component input on the TV is good or not as I don't have a component cable and i don't want to buy a cable just to find out if the input is good. I have two questions.

1) In order to test the component input on the TV to see if it is "fried" (there wasn't anything plugged into it at the time of the power surge), is it possible to use a composite cable as a substitute for the component cable (eg Y to Y, R to Pr, and W to Pb) or is there something different in the construction of composite and component cables that would cause a problem? If it is OK to do this then is there any advantage (apart from color coding) to buying a component cable, as i aready have a long composite cable?

2) When I bring the signal from my cable box to the receiver, which is the best cable to use, co-axial video cable or composite? Since I will (hopefully) be using a component cable to get from the receiver to the TV, it seems that the video signal will be compromised by the "weakest link" in the system. Since co-axial cable is used coming from the wall to the cable box, does this mean that it is a better signal transmitter than composite video cable?

[samijubal]

Component cables have a different resistance than composite cables do. If you have a large screen HDTV or a high quality high resolution TV, you might see a picture difference, on a standard TV you probably won't see any difference between composite and component cables. I would use composite cables from the box if it has the outputs for them.

[redwudz]

1. A component cable is just 3 RCA cables together. A composite cable is a RCA cable also (Audio cable). If you use 3 RCA cables, plugged into the right sockets on either end, it will work fine. You will need 3 for it to work properly. If you have a long run, you would need good quality cables. Just for a test, any RCA cables will work, even RCA audio cables. If your DVD player has component out, use that.

2. Which cable to use should be obvious. RF coax will generally have threaded ends, or push on that are similar. Composite will be RCA type push on. Check the sockets on either end. Coax is for RF (Radio Frequency) and RCA is for lower frequency video and audio.

[MACCA350]

2) When I bring the signal from my cable box to the receiver, which is the best cable to use, co-axial video cable or composite? Since I will (hopefully) be using a component cable to get from the receiver to the TV, it seems that the video signal will be compromised by the "weakest link" in the system. Since co-axial cable is used coming from the wall to the cable box, does this mean that it is a better signal transmitter than composite video cable?

Picture quality goes:-

lowest
coax
composite
svideo
component
highest

So if your choices are coax or composite, use composite

[edDV]

"define this receiver" as in "Component from receiver to TV"

1. Composite and component cables are all 75 ohm coax with RCA type connectors for a home setup. Component cables need to be the same length (Y, Pb, Pr). For a test, you could try audio cables but these will limit frequency response and create rings and reflections. If the TV isn't progressive, don't try progressive.

2. first define your "receiver" by make and model. also define the TV.

[samijubal]

All composite cables are not 75 ohm, alot are 35-50 ohm, which is not right for component hookup. Read this, everything you could want to know about component cables is here. http://www.audioholics.com/techtips/audioprinciples/interconnects/ComponentVideoCables.php

[sailgb19]

I am a little bit confused by the replies!

As far as I can tell, there is a significant design difference (i.e. impedance) between composite and component cables, that may result in a less than perfect picture if I use composite in place of component. However since my TV is not an HDTV (It is an old Toshiba CN32G90 Cinema Series, 4:3 aspect ratio - soon to be upgraded to a HDTV widescreen when prices drop a bit further!) then using a composite cable as a temporary measure (or at least to find out if the composite input works) should be OK. Is this true?

I am assuming that there is no risk of damaging the composite circuitry in my receiver by doing this? (It is a Yamaha RX-V2400)

Regarding the output from the cable box - the choices are 75 Ohm coaxial cable, composite, or S-video. Based on the answers to my questions, it appears that I should use the S-video output. However, if I do this, is there any advantage to using composite from the receiver to the TV, if I have already compromised the video signal by using S-video from the cable box to the receiver? Also, since 75 Ohm coaxial is the worst choice, then how can any of the superior cables (Composite, S-video or component) result in a better picture if the original signal is coming from the cable company along a piece of coaxial cable? Is this because the signal from the cable company is digital, but the outputs from the cable box are analog?

Hopefully someone can let me know if my understanding is correct?

PS - when will we have wireless connectors for audio and video components? Wireless computer connections are common, so why do we have to mess with these cables anyway?!?!

[edDV]

"As far as I can tell, there is a significant design difference (i.e. impedance) between composite and component cables, that may result in a less than perfect picture if I use composite in place of component."

No they are all 75ohm impedence. Video coax of all kinds is 75ohm with few exceptions*. There are 4 basic types found in the home.

a. The RF cable from the cable company. This is usually RG-6, sometimes RG-59 for short runs. It carries a broadband equalized set of frequencies of ~500-800MHZ bandwidth analog RF not digital even for the "digital" and HDTV channels. The modulation scheme is QAM. The amp on the utility pole and the input stage of the set top box equalize this cable for flat response (cable company's problem).

b. Composite NTSC/PAL single video signal, yellow connector (~6-8MHz bandwidth). Luminance and chroma are carried on the same wire.

c. S-Video NTSC/PAL Y/C dual coax cable with 4pin DIN connectors. This cable separates the color subcarrier from the luminance eliminating interference between the two.

d1. Standard definition component analog Y, Pb, Pr 3 cable set, red, green, blue connectors (~6-8MHz bandwidth). These are used between non-progressive DVD players and TV sets with component analog inputs.
The picture quality will be superior to composite or S-Video since NTSC is avoided entirely. Wal-Mart sells these for around $9.50.

d2 Wide band component analog Y, Pb, Pr 3 "double shielded" cable set, red, green, blue connectors (~12-60MHz bandwidth). These are used for progressive 60 frames per second 480p progressive connections from DVD players to "wide band" inputs on EDTV or HDTV sets. They are also used to connect 480i, 480p, 720p, 1080i HDTV set top tuners (DTV, cable, satellite) to the EDTV/HDTV set. Wal-Mart sells 10ft. sets for around $19.

RE: Yamaha RX-V2400

I think the main reason for looping the component cables through the receiver is to overlay an on-screen menu for the receiver itself. Specs are missing from the Yamaha site.

RE: "old Toshiba CN32G90"
Does it have a component analog input? If so connect your DVD player there. If not use S-Video connection.

RE: cable box
sounds like a standard cable box. I'd connect the RF out to the RF in on the TV. I'd also connect the S-Video either directly to the TV or pass through the Yamaha receiver to pick up some receiver menu overlays and then S-Video to the TV.

In the future you will probably add a EDTV or HDTV, a HD DVD player and a HDTV set top box tuner/DVR. You will be using wide band analog component or HDMI connections for these devices.

* 50ohm cables are sometimes used in Ethernet computer networks. Do not use these for video.

[Richard_G]

Just an observation, but you should live in the UK. If a TV gets fried by a power surge, the power company will buy you a new one. A friend on mine is on his third free pc (each one better than the previous) because he is in a rural area with overhead power lines and keeps getting surges.

[redwudz]

Generally in the US, depending on the power company, they are responsible to deliver you clean, safe power. If there is a surge on the line, even a 'Act of God' power surge, such as a lightning strike, they are generally responsible.

Of course, they will never tell you this. PG&E, my local supplier, will pay damages for line fluctuations that damage your appliances. However, you have to call them and tell them that it happened. They rarely contact you. Then they will send you a claim form.

They know when they have had a problem and they will pay. It may take a while, and you need receipts from a repair company of the damages so you have a repair bill.

Don't let them jerk you around, they pay out damages all the time.