Is anyone having trouble getting your Digital converter box to work with old sets?

[Tubejunke]

I have a 1956 Philco that played GREAT for longer than I have been alive, and up to the last day of over the air television broadcast. When I hooked up two different boxes I got more or less the same depressing effect. I get a picture and sound with noise in it; some type of distortion.

NO, it is not pixilating from lack of signal. I can go into the menu and there is unwanted distortion or noise. I tried channel 3 AND 4 and get a slightly different effect, but neither one is acceptable. Even my VCR didn't act exactly right, but it performed much better, but with low volume.

I am just curious what others here have experienced with the changeover, and what they have done about compatibility issues. I KNOW that this can work. My 1950 RCA TC-127 does fine but has a low volume issue, but it had that before the changeover, so I know it's the set in that case.

With the Philco I am wondering if the trouble is happening because channels 3 and 4 have NEVER been used around this area. Perhaps there are capacitors in the tuner that haven't seen voltage in many years other than for a few seconds as the selector rolled past 3 and 4.

Any input and ideas are appreciated and will make this a useful thread for now and for future TV buffs.

[DaveWM]

I watch RTV and the sound is often messed up, is it doing it on all the OTA channels?

[Tubejunke]

Originally Posted by DaveWM

I watch RTV and the sound is often messed up, is it doing it on all the OTA channels?

There are no 'over the air' channels, if that's what you mean by "OTA." I'm not sure what you mean by "RTV" either. My problem is there regardless of what DIGITAL channel I am viewing. Again, even the converter's menu has audio and video noise, so I'm thinking that there is an issue with the tuner using channels 3-4, that it has never used. I really don't know, so I hope this thread attracts some folks who have tackled converter issues.

I will add that I did swap out the matching transformer, so that's not causing it, unless they both were bad. I doubt it...

[Tony V]

Some have got better results by putting the converter box and antenna away from the set. Something about interference from the box itself was causing noise and distortion in the picture. Make sure the cable from the box isnt leaky also. I've been lucky so far in that I hadnt had any troubles with my boxes and old tv's except for an old Bendix where the signal was too strong and overloading the picture. An attenuator fixed that.

[DaveWM]

RTV is the retro TV channel I watch, digital over the air, I have a digital receiver that converts to analog out on channel 3. I have not had any problems except for some programming that seems to have lousy audio, mostly been on the RTV network (mostly some of the really old programming they broadcast).

[rca2000]

I have yet to put my converter on a truly "old' tv--but right now--I am "kinda", watching RTV on that 1985 sony KV-1371, and it works nice. I know the Sony is not really an "old tv" having digital controlled tuning and remote and such...but to most people--it is an "antique".

Perhaps I will try the converter on my 29JC20 Zenith--and see how it does. It was always pretty good on OTA signals--when analog was still around....and a Laserdisc on ch3 did OK too.

[jr_tech]

My 53 Philco was overloaded by the output of either the Channel Master or Zenith converter boxes... perhaps I need to work on the AGC, but for now, I just put an adjustable attenuator (R/S 15-678) in the antenna line and adjusted for best sound/pix.

jr

[Charlie]

Originally Posted by Tony V

Make sure the cable from the box isnt leaky also.

I had an issue with this on a set. I was getting dots across the screen till one day when I moved the coax to get a vacuum hose behind there to get at dust bunnies. After realizing the dots went away, I played with the coax for a bit and discovered that's all it was... just a certain way the wire leaned against the set.

My VCR/DVD recorder has the new style tuner in it, so can I use that as a "converter box" on my sets. I haven't really noticed any difference, but then it's rare that I watch tv thru that tuner. I'm usually watching thru satellite being that I only get one channel OTA and it's only 50% of the time. Sure miss analog... I got that 100% of the time!

[Reece]

I had a similar issue with a cable digital-to-analog setup on one TV a couple of weeks ago. Some of the channels were missing, others would pixelate. I took off one very old piece of coax and replaced it with new: problem gone. Digital likes perfect, non-lossy connections.

[kx250rider]

I've had the cheap RCA converter hooked up to several vintage sets, including my '52 Kaye-Halbert, and '65 Zenith roundie color set. No problems.

I wonder if your set is having AGC issues? I've seen early sets with keyed AGC do weird things on VCRs and DVD players. How about if you disconnect the matching transformer from the TV, and attach a piece of 300-ohm wire to the matching transformer, and let it lie around behind the TV? If the TV doesn't like the "closed circuit" connection from the box, it might be OK with the wire you laid out, just acting like a transmitting antenna. Most of my pocket TVs will pick up a fair signal that way if up close.

Charles

[Phil Nelson]

I used my Zenith converter on a few of my restored sets and didn't notice any real problems. Switching the audio from stereo to mono boosted the volume.

If channels 3 and 4 haven't been used in 54 years, it's possible that those contacts in your tuner are simply oxidized and/or dirty. I have enjoyed a huge improvement after cleaning the tuner on some of my old TVs.

Cleaning isn't difficult. I use Q-tips dipped in DeOxit. Do not "brighten up" the contacts with sandpaper or a file, or you will be a very unhappy man. The plating on contacts may be thin and delicate.

Phil Nelson

[Robert Grant]

I'm not sure exactly what kind of "noise" or "distortion" you may be experiencing, so I'll make a couple of guesses about what the problem may be.

If your local analog signals had been weak, and your picture with the converter box is prone to very high contrast or "tears up", you may be able to fix this by backing up on the AGC control on your set (presuming it has one). When only weak analog stations were feeding the set, signal overload was never a problem. With your converter box, a strong analog signal (capable of overload) is fed to your tuner, whether the DTV signal the box is receiving is across the street or from the deep fringe.

As far as audio noise, this is very common, if your box is not delivering fully-modulated audio to the set. Most CECB's have a volume control inside the box (allowing the user to change volume by remote control, even if the set does not have remote). If the volume setting (inside the CECB) is not at maximum, you are turning up the volume on the set to compensate, which reveals the noise your set's audio chain always had. A problem that is just as serious, and not as well known, is that many CECB's have two "audio modes", one for when the user is using RF input (ch3/ch4), another for when the user is using audio inputs (red/whi RCA cables). When set on "A/V out", the volume level (even on ch3/ch4 FM carrier) is far below what it would be using the "RF out" audio mode, so make sure the audio mode is set to "RF out".

That being said, I still notice that video intercarrier buzz (which, IMO, seems to have plagued all old sets, even when I was little and those sets were new) seems to be worse with CECB's than it had been with analog OTA signals, and worse with some CECB's than with others (I wonder if CECBs have a whiter max white than analog signals did?). It was a problem with my Emerson 1224, but recently replacing the 5AN8 and 5T8 tubes (in the audio IF, discriminator, first audio circuits) has made the situation much better.

[Charlie]

Originally Posted by Robert Grant

Most CECB's have a volume control inside the box (allowing the user to change volume by remote control, even if the set does not have remote). If the volume setting (inside the CECB) is not at maximum, you are turning up the volume on the set to compensate, which reveals the noise your set's audio chain always had.

My grandmother was having this issue with her old set in the living room. It's an old GE floor model from the 80's. She was complaining about how strange the audio seemed to her. Once I turned up the audio on the converter box, then turned down the TV audio, everything sounded normal again.

[andy]

...

[old_tv_nut]

Originally Posted by andy

I think a lot of the problems are caused by interference from whatever is using channel 3 and 4 now. Combine leaky 75-300 ohm baluns with weak output from the RF modulator, and you're likely to see interference problems. I've found that adding an RF amplifier between the RF modulator, and the TV helps a lot.

This does not make sense at all. The converter box should put out more than enough RF. Check the internal cabling of the set.

For the original poster - if the picture is really bad (sounds like it) and is not an AGC problem, could it be that fine tuning of channel 3 (or 4) is way off and you are attempting to receive the lower sideband? Hook up a VCR with channel 3 output and see if you get the same bad result. RF output of a converter box is essentially the same as RF from a VCR.