RCA 721TS Help

[old_coot88]

Often you can hear a faint buzz coming from the V.out transformer and/or yoke windings. If you can hear it, try turning the V.hold control stop-to-stop, and you'll hear the buzz change in pitch. The pitch change will usually tell you whether the osc. is running too fast or too slow.
This in turn can be a troubleshooting guide.

[Radiotronman]

I replaced a few more out of tolerance resistors in the vertical oscillator circuit with little improvement. So I went to my 1950s tv repair bookshelf for some pictorial help. My book said split vertical picture is due to a few things, including misadjusted vertical hold control. I laughed and thought....no kidding! But I figured nothing else has worked and I didn't really spray this control. I rocked it quickly from one end to another and bingo, one picture!

[old_coot88]

Booyah! Say hey!

[EdKozk2]

Picture looks nice.

[bandersen]

Nice, but a little odd. The image should be rectangular - not fill the screen. Something more like this. I wonder if the yoke is not pushed all the way forward or the HV is too low ?

[old_coot88]

Originally Posted by bandersen

Nice, but a little odd. The image should be rectangular - not fill the screen... I wonder if the yoke is not pushed all the way forward...

Wouldn't that cause a neck shadow?

[ChrisW6ATV]

The last picture does have what looks like a neck shadow (I see a dark ring around the picture on the CRT face). Also, adjusting the height and vertical linearity for a "full screen" raster on a round CRT can itself cause the vertical-hold control range to be less than ideal. (Except on a round-bezel Zenith, of course.)

[dieseljeep]

Originally Posted by bandersen

Nice, but a little odd. The image should be rectangular - not fill the screen. Something more like this. I wonder if the yoke is not pushed all the way forward or the HV is too low ?

What kind of signal source is used? With my Zenith DTV convertor, I can get a small squared screen on some channels. With the caption, "set by program".

[bandersen]

Over the air low power NTSC. We still have LPTV channel 6 in Chicago.

[Radiotronman]

The darkness around mine is because I haven't perfectly adjusted the yoke and focus coil. I will do that when I get it ready to finally put back in the case. Getting the adjustable mounts at the proper depths will also help the centering.

[Radiotronman]

Got it all back together....time to watch tv!

[Eric H]

Do you always watch TV sideways?

[Arcanine]

Originally Posted by bandersen

Over the air low power NTSC. We still have LPTV channel 6 in Chicago.

I can only hear the audio from them here. Decently I might add, but even on a huge TV Beam aimed at Chicago I can't see their picture.

A couple times when conditions were exceptional and beyond good conditions for FM propagation, back in the Q87 days, I picked them up in Fon Du Lac Wisconsin, and kept a mostly stable signal all the way back to Lake Geneva.

Was pretty cool.

[Electronic M]

Originally Posted by Eric H

Do you always watch TV sideways?

I noticed that too. If he is using a Windows machine to upload, then he should use windows photo viewer to check for rotated photos, and use it's rotate 90 degrees buttons to get the pictures right side up prior to upload.....

[Boobtubeman]

Perhaps its in front of a couch and he likes to watch tv laying on his side?

SR