Why is my TV picture flickering when I don't use a VCR?

February 12, 2007 8:54 AM

Electronics filter: When I connect Dishnetwork straight to my television, the picture is flickery and unwatchable. When I run it through my old VCR first, it's fine.

I know it isn't a Dishnetwork problem, because exactly the same thing happened when I had cable. What is my VCR doing that makes the signal work, and is there something else I could use in its place?

posted by Pater Aletheias to technology (7 comments total)

I have noticed this problem with my RCA HD Monitor. Digital cable looks like crap through it. The problem is the internal tuner in the TV sucks. The VCR acting as a tuner allows me to leave the TV on ch. 3 and tune through it instead. With the VCR method, all channels are clean and clear, with the TV tuner, anything abouve ch. 20 starts looking awful.

It took me a few service calls before a cable tech finally had me swap sets to point this out - kind of obvious but the TV in question is new and I never thought it would be a bad tuner issue.
posted by jtoth at 9:12 AM on February 12, 2007

Is the picture tearing or rolling? That means the TV is unable to sync. Chances are your VCR has a better sync detector and is inserting its own reconditioned sync pulses that the TV is able to cope with. Something like that.
posted by cillit bang at 9:21 AM on February 12, 2007

Yeah, I figured the problem must be the TV somehow. (Mine is a five year old Philips that works great otherwise.) Is there some small device I could attach to the cable that would function as a tuner? (I'm pretty ignorant about this stuff.)
posted by Pater Aletheias at 9:21 AM on February 12, 2007

What kind of cable are you using? A coax? If so then its RF. Dont use RF unless you absolutely have to.

Does your TV have RCA/composite inputs that use these cables? If so then just use them and see if it helps.

If you cant use composite inputs then see if your TV has a 'cable tv' mode. Set it to this mode and tune your TV to 3 or 4 or whatever channel your box is outputting.
posted by damn dirty ape at 9:44 AM on February 12, 2007

Could be a long answer.

Dish network probably has composite video outputs AND RF outputs. You should not have the problem with the CV outputs, but you'll need to have correct cables as specified above AND have the TV setup look at the video inputs, not the RF.

I disagree that RF is a lot worse. The TV is designed to deal with it. You have provided too little info to determine if you have it hooked up properly. have you got it set to the wrong channel? (Like maybe 3 instead of 4 or vice versa?)

The only way to troubleshoot this sort of thing without test equipment is swapping out components, doing comparisons between different approaches, reasoning out what is going on.

IF the problem is your RF modulator on the Dishnetwork, which seems unlikely because of the fact that your cable did it too, you could use a distribution amp to boost the signal.

If the problem is a bad RF connection at your TV or via the coax, you MIGHT seen an improvement by boosting the signal. Cost of a distribution amp at the local hardware store is 20 bux.

Some older TVs have 75 and 300 Ohm inputs. Are you using the right one? Again, this is something omitted from your question that could be answered with a glance. This matters because there are other internal components that might be involved, miswired, broken, missing.

To me, it sounds like the TV is insensitive to RF. The old cable box isn't. It either demodulates/remodulates the signal and it comes out stronger, or it has an internal distribution amp that does the boosting directly.

Try a distribution amp. (Take it back if it doesn't work.)

My guess anyway.
posted by FauxScot at 11:40 AM on February 12, 2007

The current set-up is a coaxial cable running to the VCR, with RCA connectors going from the VCR to the TV. Coaxial straight to the TV is what was flickering and unwatchable.
posted by Pater Aletheias at 1:56 PM on February 12, 2007

Doing that bypasses the TV's tuner, so it might be that that's on the fritz. Does the sat box have RCA?
posted by cillit bang at 4:06 PM on February 12, 2007