PL5060N - MuxLab - Pace Cable box Problem

[Holt]

We installed 4 PL5060N HP TVs into a lounge that we are doing the AV for.

Here is a single TV's connectivity:

From the Pace cable box we wire the component out to a MuxLab (component to cat5e video balun Part #: 500050). The cat5e runs (all runs less than 100 ft.) to an identical MuxLab (component to cat5e video balun) on the TVs end. We then wire the component output of the MuxLab to the TV's component input.

Everything works fine until the TV's picture randomly starts having a problem where a horizontal band (about 1/8th of the picture's height and just below center) starts jumping left and right like it is out of sync.

I'm trying to diagnose the problem to see which of these 3 components is causing the problem:

- Cable box
- MuxLabs
- TV

All these actions will fix the problem independently:

- Turn on and off the cable box

- Unplug the cat5e from either of the MuxLabs and plug back in

- Turn the TV completely off and force the TV to reinitialize (Simply forcing the TV into hibernate mode and back on does not fix the problem)

- Use the TVs remote to switch to a different source and then back to the original source.

It appears to me that any action which forces the TV to resync with the video signal will fix the problem. This assumes that when the TV goes into and out of hibernate mode that there is no resyncing of the video signal.

From the above info, my intial thoughts are that the TV is the problem. However, this is occuring on 3 of the 4 TVs we put into the lounge, which makes me reconsider the source of the problem because what are the chances that 3 of the 4 TVs are bad. The 4th TV may also be experiencing the problem because we haven't been running it as much.

Sometimes the TVs will go all day without exhibiting the problem. Other times our above fixes will work for about 10 minutes and then we see the problem again.

Obviously from my description above, I am not a AV expert so any suggestions would be great.

Thanks,

Holt

 

[BraveSirRobbin]

Could you temporarily eliminate the baluns by running coax say on the floor or ceiling to one of the TV's to rule them out?

 

[upstatemike]

Could be a combination problem. Low sync out of the Pace plus additional loss of sync signal through the baluns. Sounds like it is right on the edge if you can re-sync it so easily.

I would tend to blame the cable box.

 

[Holt]

Is the sync signal superimposed on top of the component in some way. Can someone point me to a good explanation of the transmission technology.

Also, are there any good testers that will help me diagnose the problem better than just try something and wait to see if it fails.

Thanks,

Holt

 

[mdesmarais]

Yes, sync is added to the Luma (Y) signal. I can't find a nice clean reference, but this link should give you some ideas. . .

http://www.tektronix.com/Measurement/cgi-b...eSet=television

Now, thats for composite, so you don't need to worry about the color burst stuff.

Do you have access to an oscilloscope? That would let you check the sync signal for degradation. There are more sophisticated video testers, but I imagine that would be a bit pricey for a small job.

Markd

 

[Holt]

We don't have a scope, but we replaced the cable box with a dvd player (left in the CAT V and the Muxlabs) and it worked perfect. Ran it for several hours and no problems.

Is this an indication that the problem is the cable box or is there something different enough in the way the DVD player transmits over component that we still don't know the problem. Say maybe a digital transmission (that is say less vulnerable to noise) vs. some analog scheme.

Thanks,

Holt

 

[mdesmarais]

They should transmit the same- component is component- analog signal. The DVD player probably has a higher sync level.

So yes, this would point to the cable box as the culprit.

 

[Holt]

We are bringing in the cable guys to check out the cable boxes and cable feed.

Thanks,

Holt