Electric Pulsation
 

Hi All,

I have two roundie color tvs that seem to be sensitive to the pulsations in the electric current. I notice it in the incadescent light bulbs in my house also, but not in my flat panel sets. Am I correct in assuming that the electric service is the cause, or is there something I should check on the tvs? One is a 1964 Magnavox comb, and the other is a 1967 Zenith.

Thank you for any advice you can give me.

Frank

normal for sets to react to sudden changes in voltage due to loads like AC coming on, I have a printer that causes it, you can see the pic effected about every 15 seconds when the printer is on and acting up.

Like I said, both sets do it, so I knew it wasn't something peculiar to one set or the other.

AC units kicking on are the worst offenders, they can make the picture fall out of sync if bad enough.

You might also notice it when the icebox kicks on. A washing machine (older one with an AC motor and transmission) could also cause it while agitating. Older homes are the worst offenders. A neighbor I had years ago had a home that ran on a total of 4 breakers... any item that used significant current would be noticed throughout the entire house.

Very noticeable in older homes with just a couple of fuses and appliances going: typical washing machine pulsation making the TV picture shrink slightly in time with the load on the motor. I knew a family in Beaumont TX where in the summertime the lady would start ironing, then get too warm, and switch on the attic fan. The starting load of the fan motor would blow the fuse. They had to teach her to unplug the iron, turn on the fan, then plug the iron back in. Living on the edge!

I had a increasingly noticeable problem like you're describing about 5 years ago. If the central air or heat came on, I'd lose width on my sets. The washing machine caused problems as well.

The power transformer on the pole outside only services my house. That tranny was pretty old... even starting to show a lot of surface rust. I called Entergy, and they came out to have a look. At first glance, the guy said it could be the problem. He told me he'd come out again with a device to put it under a heavy load and determine if the tranny needed changing. A couple of weeks later, I went to sea and was gone for two months. When I returned home, there was a brand-new tranny on the pole, and the voltage drop issues I had been experiencing completely went away. No problems since then.

The house is only about 15 years old, but the electrical service outside is ancient. Here on Long Island, LIPA is a joke.

You mentioned a computer printer. Most laser printers have a heat fuser assembly that can draw 1000 watts plus or minus. Keep that in mind. Newer flat TV's have regulated Switching power supplies that do well regulation wise so you won't see line volt prob's.

Wow... that's a lot of juice for a printer!

Keep in mind the older sets used a straight foward power supply with no form of voltage regulation. The newer sets all have voltage regulators with for the most part can handle a wide swing on the input voltage.

I know this may sound strange, but where I live, there's no above ground power poles or anything like that, it's all underground.

Where would they even put the transformers for situations like this?

In subdivisions with underground wiring, there will often be metal transformer boxes above ground, sometimes in between houses, to serve several houses. I'm not aware of underground transformers but there may be some but wonder about such an installation flooding.

You ain't kidding!
I was from Mastic myself....

Ha-ha... some people here might be too young to know what an attic fan is! :D

You remind me of my Uncle when he and my Aunt moved off the farm to a new house in town. When I visited, he showed me how many circuits he was putting in "so my TV picture won't shrink when she irons!"

Is that what these boxes are? (Sorry about the poor pic, this was taken from my cars dash cam).

http://img.photobucket.com/albums/v3...dragon/box.png

I was scrolling down to say what you just said, oldtvman, but you beat me to it.

Hard to see how big that is - in my old neighborhood, they were in a green box about 3 feet by 4 feet in size. It just struck me that I don't know where they are in my current neighborhood - wonder if they could be on the poles just outside the subdivision? Have to take a look at my neighbors' back yards.

Those dimensions pretty much match this green box.

Those residential, single-phase pad-mount transformers have very low impedance (internal resistance). That means higher available short-circuit current and ultimately better voltage regulation.

We had the same issues when using just a vacuum cleaner show up on the 1972 Sony KV1210.
There was a Truman-Era transformer with brown porcelains and wires, not terminals (7 kVA and rated for only 29 amps) on the road pole and 100 feet of #4 aluminum overhead wire to a small-round meter base. When you add up all that series resistance and multiply it by even 20 amps, the voltage drop is enough to be VERY noticeable on anything old that lights up

Charlie noted some may not know what an attic fan is: Back in ancient times before A/C was common, houses in the South often had attic fans, what they call today whole house fans. There would be a louvered opening in a hallway ceiling and a large fan, 36 to 48" diameter in the attic. You'd leave the house windows open and this thing would exhaust heat from the house into the attic and out the attic vents. As kids we'd wait until the coast was clear and then close all the windows but one and stand in the huge blast from that window. You were warned not to close all the windows with the fan on because it could pull the wallpaper off the walls! Sometimes it would slam doors to a room if a lot of air was coming from that room.

Those pad mounted transformers for underground wiring: I saw one with the cover off one time and it looked like a gigantic bare audio output transformer with the usual E and I laminations, and a bunch of screw terminals.

Still have a working Reed attic fan in New Orleans! I use a "always on the inverter" sine wave UPS for the TV's. It stops them from getting upset when the AC kicks on. The UPS is an industrial 3500 watt unit that is connected to one circuit of the house. We had a tornado come thru a few years ago and knock out the power. The neighbor across the street wanted to know how my power stayed on. I looked at her and said "you remember the Twilight Zone with the neighborhood controlled by the aliens? If memory serves me right I think it was titled "Main Street".
She was not amused.......

Rounded dark green boxes about the size of a table model roundy color TV, sitting on the ground right in plain sight. I used to live in Lakeland Fl and the 70's development we lived in had them, same ones were also used at the apartment I just moved out of here in Wi.

I'm starting to miss the electrical grid there as I just started using my vintage sets again and a some times of day the lighting flickers and the sets bloom(usually several times a minute) which is annoying the crap out of me!....When I get time I'm going to try and track down the source of the issue.:grumpy:

Usually painted green, in an attempt to blend in with the landscaping. And they have a padlock on an access door, to keep kids from finding 8 to 13KV at a very low impedance.

It was titled "The Monsters Are Due On Maple Street". In the new Twilight Zone series they told the same story but instead of aliens, the government was the one cutting the power to test the reaction of citizens in a crisis.

I was chucklin' at 'icebox', but didn't think I should say anything! :)

It's all good, though!

Chip

one thing that gets overlooked alot is how good is fuse panel outside grounding rod connection, it can look good and even test ok, but when your over-all power demands increase the ground becomes resisted and any slight surge or demand becomes really noticable ,what you can do to check it is turn on what you normialy do to make the surges or just turn on alot of stuff ,clean a spot on the ground rod file/sandpaper and on the panel wire ,set your multimeter to a/c scale put one leed on the rod and other on the wire and see how many volts you read if too much shows than clean the ground connection see if surging stops. make sure if you disconect your ground to clean it its best turn off your power or you might complete the ground .

Be very careful poking around inside a circuit breaker or fuse panel. Not only is there the usual shock hazard, but another serious hazard called "Arc blast". You've seen sparks when a short happens, but most of those had limited small amounts of power behind them. But the feed from the power company to your house has a very large amount of power available to a short circuit. Enough to melt and vaporize say a screwdriver shaft. And you really don't want your face anywhere near that.

you only should have to turn off the main breaker to clean your ground rod,and if its a newer home it should have second saftey box ground . if you messing around with your lead in wiring before the main breaker you bet youll get a arc blast or what blows the easyest, the screwdriver / meter / or if get enough load the pole fuse will open ,then your power company comes out to vist. if your updating your breaker panel from 100- 200 amp you will have to pull your meter, dont try to it any other way .