RCA 630TS Slight Picture Imperfection

[M3-SRT8]

Hi Boys,

In the continuing saga of the 630TS, I'm trying to localize a small picture quality quirk.

The GE 10BP4A CRT is installed and adjusted. Pic looks fine, except there is an occasional horizontal band of noise, about 1" tall, somewhat faint. It travels upwards to the top, and reappears at the bottom. Not bad, but, I can't adjust it out, and I'd like to eliminate it.

Any Ideas, Brain Trust?

Thanks;

LJB 8)

[jpdylon]

line noise maybe? Are there any computers or switching power supplies near by?

Try moving the set to another room and outlet. I assume that ALL of the power supply electrolytics were replaced and not reformed?

[Old1625]

If it does it intermittantly try spritzing the on-off switch with tuner juice. Sometimes a poor line contact can arc gently enough not to heat up things too much and cause smoke, but suffienient to put a line of hash on the screen and moving up through it.

A funky rectifier tube could also perhaps be your problem. At some part of the rectified waveform it can generate a burst of noise much in the way a horizontal sweep tube can do that creates a vertical line of hash (sometimes nicknamed "snivet").

[M3-SRT8]

Originally Posted by jpdylon

line noise maybe? Are there any computers or switching power supplies near by?

Try moving the set to another room and outlet. I assume that ALL of the power supply electrolytics were replaced and not reformed?

All Electrolytics and Tube Capacitors replaced w/heat shrink tubing. All leads nicely routed.

There is a lot of stuff hooked up to the TV. There's a DVD Player, Tube Stereo amp, RF Demodulator, Cable Box, ALL with high quality shielded interconnects.

LJB

[jpdylon]

It could also be a ground loop problem considering the number of pieces connected to the set. Try running the set with only rabbit ears and see if you still have the interference. If not, start re-connecting each piece of equipment until the bar appears - then you've found the troublesome piece. In which case, you can obtain a ground loop isolator

If the problem exists even with only rabbit ears, Definitely check the power switch and rectifier as mentioned by Old1625. You may also have a short or excessive leakage in one of the tuner or IF tubes. If you have an o-scope you'll be able to track down the noise a lot easier.

[M3-SRT8]

Rectifier Tubes are new Chinese 5U4's. I've cleaned and lubed the On-Off Volume Switch (or, "Svitch", as Zworkin would've said).

I'll check for Ground Loops. Would everything plugged into a line conditioner help the Ground Loop problem?

LJB

[Old1625]

Originally Posted by M3-SRT8

All Electrolytics and Tube Capacitors replaced w/heat shrink tubing. All leads nicely routed.

There is a lot of stuff hooked up to the TV. There's a DVD Player, Tube Stereo amp, RF Demodulator, Cable Box, ALL with high quality shielded interconnects.

LJB

Cripes! OK, here we go. The previous response by jpdylon to this is the way to go. Elimination of all that gear. My bad for not asking this.

I got a call from a city museum back in the '80s about the same complaint. They had set up a VTR to feed several RCA Lyceum A/V monitors or equiv. The story told to me on arrival was that they originally had jerryrigged everything using cheap molded-end extension cords, hanging off all the third (ground) prongs of the power cords from the VTR and the monitors with adaptors. While it was a clumsy and perhaps unsafe arrangement it worked. Then some wuss came in and saw all this in a public bldg and raised a yell. Then the museum called in an electrician to install a system of conduit and outlets to serve in place of the extension cords running from original outlets. Now it was up to code, but now there was a horizontal line of hash creeping up the screen of every monitor. I got paid for that job, but didn't lift a finger. All I said was "Use the same adaptors you had on before to lift the ground on the power cords of all the monitors, and leave the VTR cord unlifted." While I waited and amused myself with the exhibits the museum personnel scrambled to find the adaptors and did just that. Fifteen minutes later we fired up the A/V system and every monitor gave a clean picture once again.

This "mini rant" of mine I post as general advice that applies not only to video but also for that annoying hum or buzz that may be encountered by audio enthusiasts as CSA electrical safety standards metastasize into the consumer electronics market, placing 3-wire power cords on equipment.

I'm not sure all your playwiths have sissy cords on them; they probably all have 2 wire type. So--if power line ground loop is the culprit--you are limited to eliminating offending gear. Or you may need to run the telly through a large and good-quality isoformer.

Again, sorry for the dissertation.

[M3-SRT8]

Thanks again, Dave.

We gotsta get together sometime...

LJB