Focusing a television

My parents have an old tv that seems to have gone out of focus, if that’s possible. I can’t find a control for this. It’s an RCA ColorTrak, probably from the 80s. Any suggestions from anyone?


There may be something adjustable inside the television, but do you think it’s worth the headaches? I assume it’s smaller then 30"? New televisions in that size range are amazingly cheap these days.

There’s a kind of grid that is part of the tube that can go out of alignment, I think. It’s possibly that.

But man, just get them a new TV. They don’t even have TV Repair shops anymore, they’re so disposably cheap.

There is an adjustment for focus. It goes hand-in-hand with one called “screen”. Both usually need to be adjusted to get a good focus back. (Assuming the yoke is not out of alignment).

Rarely, on old TVs, these might be accessible on the back using a plastic screwdriver. Not many sets have this feature though. If you have these screws, report back and I’ll let you know how to adjust things right.

If it is not accessible, then do not take off the cover to adjust them. Just asking this questions indicates you don’t enough about what is what inside a TV that the danger of killing yourself is high. I really mean killing as in ending up dead.

A TV tech can do this adjustment easily, but will charge so much that buying a replacement is far, far cheaper.

The focus control rarely drifts out of alignment by itself. More likely (on an old TV), the CRT is dying, which also causes poor focus, particularly on bright areas of the picture. Replacing this would be more expensive than buying a new set, though.

I second all the advice not to open the case. I do, because I’ve been doing eletronics as a hobby for over 30 years now, and I started with repairs. But to be honest, even though I taught courses in electronics repair a few times in my youth, I’m probably crazy to do it myself, knowing that experienced full-time repairmen got killed every year.

That, said, you should have the following controls on the back of an RCA Colortrak, IIRC:

a) a Focus adjustment that requires a plastic TV adjustment too (like a straight 6" double-ended Allen wrench, I believe Radio Shack still sells a pair of for a few bucks)
b) a Sharpness knob protruding from the back
c) 3 three screw head adjustments labeled “Drivers”: Red, Green and Blue.These can cause something that can be taken as “out of focus” if they are slightly out of kilter, but getting all three right is a little filter

Those are the ones you re likely to need to adjust, There will be other labeled knobs (e.g. vertical and horizontal hold, and on older sets, vertical and horizontal size, which ere later moved inside the case) – and often a few unlabeled knobs on those older RCAs. Newer units in that range, you might have a “service” switch, which won’t help you at the moment. MARK THE CURRENT SETTING ON ALL OF THESE, just for reference. You might experiment with those a bit, but even if you don’t, it doesn’t hurt anything, and someday you may be grateful. An unlabeled knob can only go out of adjustment

If you can report back with details of what you see, I may be able to help more, but dammit, Jim, I’m a doctor not a TV repairman. I don’t have schematics/manuals.

It’s not enough to just unplug the TV and think its safe. There are capacitors that are fully charged waiting for someone to come along and touch the wrong things then…

you’re dead
(or so I’ve been told)

There’s only one capacitor that matters, and that’s the Picture Tube.
Still, if you don’t know what you are doing, you shouldn’t put your hands in a TV.

yep, the Flyback Transformer is what you have to look out for, it can bite, hard, back in the days of the G3 iMacs and old CRT Apple Studio displays, I had to do “Live” adjustments to them, adjustments when the monitor was fully powered up and running, I had to be extremely careful

luckilly, I’ve never been zapped, had a couple close calls, but never been shocked, and since Apple has moved away from CRT based machines (the eMac was CRT based, but never required live monitor adjustments, still it was the last dangerous machine) the danger is largely gone

in short, if you have to ask, you really should NOT be poking around inside that TV

a 15" iMac G3, when fully charged, carried around 30,000 volts, not sure on the amps, but enough to be lethal

put down the screwdriver and step away from the TV, please…

You’ve been told correctly. We used to have great fun in Intermediate Physics Lab charging up capacitors and tossing them into a little glove of aluminum foil sitting on the workbench. They’d leave big gaping holes in the fold where the current would basically explosively vaporize the foil.

However, the adjustment screws that ftg mentions should be on the back of the t.v. and accessible without removing anything. Honestly, though, after 25 years degradation in the focusing coils and the cathode are probably going to render the t.v. of pretty poor image quality anyway. You should be able to pick up a 30" flatscreen for something like US$600 or less if you shop around, and I’ve seen 20" LCD monitors with a tuner in the the $150 range, offering better definition and image quality than a brand new CRT ever had. If you need further justification, they also suck down a small fraction of the electricity, so you’re saving both money and not wasting energy.


First off, it’s obsolete. In a year and a half, it will not be usable as a TV unless you feed it with signal from a cable box or HDTV tuner.

Second, it’s 25 or more years old. RCA’s CTC-81 Color Trak chassis was a venerable old workhorse that carried on in various flavors for a good many years. But it’s still 25 or more years old. And it’s still obsolete.

On to the focus - somewhere in the bottom left of the TV’s backside is where the focus control lives. It’s part of the high-voltage circuitry, and will either be accessible from behind without taking the set’s back off, or it will only be internally accessible, and somewhere on the flyback.

Don’t know what a flyback is? Then please stop reading and go buy a modern TV. You can be seriously killed here. If the set’s healthy, there will be about 32,000 volts lurking in that section, just waiting to bite.

The “drive” and some related internal controls are for color balance setup, rather than focus - they govern the respective strengths of the red, green and blue components of the image. The “service” switch collapses the vertical scan into a single horizontal line so a tech can do a quickie job of bringing up the colors to produce a white line.

Did I mention that the TV is at least 25 years old and obsolete?