Emerson 609 projection TV

[Electronic M]

If face focus is good, look into optical focus. There may be mechanical adjustments for it.

[Phil Nelson]

Yes, there are several mechanical adjustments, as the Rider manual shows in detail.

I temporarily reconnected the broken wire with a clip lead, which brought back the power supply and full deflection. Now I'm back where I was before, with lousy focus. This is the best I can get using the two electronic focus controls:



The focus on the CRT face looks good to my eye, so I'm guessing that one or both of the reinstalled mirrors is cockeyed. I didn't mess with any of the mechanical adjusters before, such as the tilt adjusters on the base of the box. It's possible that some adjuster was seriously screwed up long ago, but the image that I got before resilvering the mirror was much closer to focus (and correct screen geometry) than this. Maybe I'll spot something obvious after I open the optical box back up.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[old_coot88]

This is a dumb question, but does the resilvered mirror have a protective film that needs to be peeled off?

The reason for asking is, I got skunked that way once with a new camera that was blurry til I figgered out what was causing it.

[jr_tech]

Is the mirror adjusted to be exactly 45 degrees to the optical axis?

jr

[Zenith6S321]

Originally Posted by Electronic M

If face focus is good, look into optical focus. There may be mechanical adjustments for it.

I agree, that with good focus on the CRT, the poor focus on the screen must be due to a miss-alignment in the optical path.

I have not worked on your projection TV model, but I have adjusted Barco projectors that have a Scheimpflug lens mount that allows you to adjust left-right and top-bottom optical focus. If you can tilt either the CRT face, the projection screen, or possibly the lens plane you may be able to correct the problem. See if you can find any mechanical adjustments that will let you tilt one optical element with respect to the others. I suggest you try to get good focus at the center of the image and then tilt the CRT, lens, or projection screen to adjust left-right and then top-bottom focus.

Dave

[Phil Nelson]

There wasn't any protective film on the resilvered mirror.

I didn't measure the angle of the plane mirror, so that's worth checking. There is very little range of movement for that mirror, once you have adjusted it so that the CRT is centered and clears the hole. There's a bit of elbow room, however. There are no adjusters for the spherical mirror, which is bolted perpendicularly inside the front wall of the box.

The manuals say nothing about installing or adjusting these mirrors, which was outside the scope of ordinary service, I guess. They must have used special jigs in the factory for this task. Due to X-rays, you can't loosen the mirrors and fiddle with them to watch the effect while the TV is playing, so the process might be tedious:

-- Make a little adjustment.
-- Close up box.
-- Turn on TV and view the screen.
-- Turn off TV and open the box.
-- Repeat as needed.

The manual does describe a bunch of adjusters for the optical system, including one on the corrector lens, but I don't want to mess with those until I confirm that the internal mirrors are installed as well as I can manage.

Phil Nelson