Moving TV trashes purity? - Page 2 - Videokarma.org TV - Video

oldtvman · #16 03-10-2010, 08:05 AM

If you read any of the old Rca service literature you always set the height and width then due purity. With the old sets even running a sweeper in front of the screen could change the purity.

jr_tech · #17 03-10-2010, 04:15 PM

Wow! that set looks like NEW!

Did you re-cap the whole chassis, or were many of the original caps Mylar?

jr

Phil Nelson · #18 03-10-2010, 05:03 PM

I replaced all of the electrolytics on general principles. I left alone the original Mylars, except for five on the convergence board and one on the vertical board.

Phil

marty59 · #19 03-10-2010, 09:36 PM

Degaussing coils were common sellers back in the day, not just for TV Techs. Usually smaller, cheaper than the "pro" models but did the job.

bgadow · #20 03-10-2010, 10:38 PM

I once rode on a ferry boat that had some 27" tv sets in the cabin. They turned them on at the dock and the picture were great; as soon as the boat started moving the color went to pot and did all kinds of swirling on the whole trip. Noticed the same thing on a jetliner a few years ago, one that still had crt monitors.

Findm-Keepm · #21 03-10-2010, 11:18 PM

Quote:

Originally Posted by bgadow

I once rode on a ferry boat that had some 27" tv sets in the cabin. They turned them on at the dock and the picture were great; as soon as the boat started moving the color went to pot and did all kinds of swirling on the whole trip. Noticed the same thing on a jetliner a few years ago, one that still had crt monitors.

Same on Navy Aircraft Carriers, only worse - the ship has it's own degaussing system (for magnetic mine protection) - when it fires off (automatically!) it leaves a wonderful rainbow! Forrest is now green and Bubba is now blue.....

I kept a manual degaussing coil in my desk for those very moments.

Cheers,

miniman82 · #22 03-11-2010, 05:24 AM

Heh, I know what that's all about. That's what makes LCD's so nice, you can bring a cheap one on cruise and not have to worry about bringing it back when you get to home port. The 13" color sets we had in our shop (I'm an AE1) were always garbage, no matter where the ship went- had one of those degaussing lines running right through the place!

Bad thing is once the screen is damaged by the ship, there's nothing the internal degausser can do about it. Maybe it's too weak, but it seems to me most of the sets that were on deployment had permanently bent shadow masks. Oh well, the CRT's days are numbered anyhow.

Jeffhs · #23 03-11-2010, 11:22 AM

I have an RCA XL-100 CTC185 table model (19") that fell off its stand last year. The set worked afterward, but I noticed color splotches all over the picture. I tolerated the problem for a few hours, then decided to at least try to fix it. Had an old PM speaker laying around, so I brought it out and pressed the magnet against the CRT screen. A couple of sweeps across the screen and the splotches disappeared. The only thing I can figure is that when the set fell (face down), the shadow mask got bent, and the magnet treatment reshaped it. I don't know if this will work again (the TV is ten years old), but the magnet did get rid of the color distortions this time around.

I'm amazed the automatic degausser didn't eliminate the splotches the first time I turned on the set after it fell. It was suggested to me in this forum that perhaps the degausser was not operating; if it were, it would have eliminated the splotches the next time the set was powered on. I'm not sure myself if the degausser works or not, although I do hear two clicks each time I power on the set. The TV works perfectly from then on.

Hmmm. Now I'm wondering. Why am I hearing two clicks when I turn the TV on? I'm sure the first is the relay for the auto-degausser, but the second one has me baffled. As I said, the set works exceptionally well once turned on, so I don't think there are any problems with the power supply or anything else associated with it; the only thing I can come up with is that the first click is the relay closing, while the second one is the same relay opening. Or is there a start-up relay in the set's power supply that opens and closes along with the degausser's?

Thanks in advance for any advice on this. I hadn't been thinking much about the cause of these relay clicks until I started writing this post. Why would a modern TV power supply even need a start-up relay in the first place? After all, there was never any need for relays in tube-powered sets, except in remote-control models in which a relay was used for AC power switching. The automatic degaussing circuits in older sets, moreover, did not use a relay, but a thermistor. I wonder why the design of today's TVs seemingly has reverted to mechanical relays to activate and deactivate the degausser, when thermistors did the job exceedingly well for decades in older sets?

Charlie · #24 03-11-2010, 12:34 PM

Phil, those screen shots are awesome! Hell... even the ones with the bad purity look sharp!

You certainly don't have to move a set far to get it out of whack. Here on the ship (back at work again since yesterday), TV's, computer monitors, radar screens... they all get out of whack while changing course. When we go thru the Mississippi River (lots of winding turns), you can actually watch the colors come and go as we turn back and forth. The computer CRT monitors (just two left that haven't been replaced) and the radars see a lot of use with the degauss buttons. The TV's are turned off an on enough to keep them clean.

Not long ago, the 3rd mate told me his TV was really out of whack and turning it off and on wouldn't fix it. I got the chief's soldering gun, waved it in front of the mates screen, and presto! Color fixed again! They "think" I'm some kind of miracle worker.

Reece · #25 03-12-2010, 08:09 AM

Charlie wrote: They "think" I'm some kind of miracle worker.

The kids would occasionally play around with a magnet and get nice rainbows on the TV. I took the "I" laminations out of an old transformer and would plug this in across the room and move slowly towards the TV waving it around and make the rainbows go away. Didn't want to confiscate magnets: too much fun.

wa2ise · #26 03-12-2010, 01:13 PM

Quote:

Originally Posted by Reece

[ I took the "I" laminations out of an old transformer and would plug this in across the room and move slowly towards the TV waving it around and make the rainbows go away.

An old Weller soldering gun works well for this too. Enough stray 60Hz magnetic field.

Phil: That restored TV looks quite excellent, good work.

bluenorm · #27 03-12-2010, 02:32 PM

Beautiful set and excellent restoration. CTC 11 they have a very nice color rendition .

Phil Nelson · #28 03-12-2010, 03:51 PM

Quote:

Originally Posted by bluenorm

CTC 11 they have a very nice color rendition .

Yeah. I was inspired by this one, so I went back to my second 11 and re-did the whole setup, starting with degaussing and gray scale. Crummy snapshot, but you get the idea.

Phil

zenith2134 · #29 03-12-2010, 04:10 PM

Same thing happened when I was on a cruise a few summers back. The ship had a small video-arcade in the aft section, and some of the CRT-based games had blotches of purple, rainbow effects, etc. indicative of magnetization. My theory is that since they are almost never turned off, they never get the chance to degauss. And naturally the ship moves around a LOT during one voyage, let alone many...

old_tv_nut · #30 03-13-2010, 02:27 AM

Quote:

Originally Posted by Reece

Charlie wrote: They "think" I'm some kind of miracle worker.

The kids would occasionally play around with a magnet and get nice rainbows on the TV. I took the "I" laminations out of an old transformer and would plug this in across the room and move slowly towards the TV waving it around and make the rainbows go away. Didn't want to confiscate magnets: too much fun.

This is OK with relatively weak toy magnets. Don't try a really strong magnet, it could permanently deform the shadow mask.