Motorola 12K2 TS-23B First TV Restore

[rwilson]

I replaced all of the wax capacitor and the filter caps. Only a few resistors so I took a chance on those. The voltages are close.
The sound is fine but the video is like this. Now that I'm about to post this I think I should have had a cross hatch screen.
There is no yoke centering magnets. With the focus coil you can make it pull down but then there is much keystone.
Maybe with the picture someone can offer some suggestions.

A thing that is bothering me is the ground seems to float above the chassis unlike what is on the schematic. And while this is a TS-23B it has some wiring like the TS-53. The yoke wiring is one thing.

[MadMan]

Are you putting a signal into it, and that's what the picture looks like?

Have you checked the tubes?

Maybe it just needs the vertical controls messed with... or one of the controls is bad.

[EdKozk2]

Hi,
I just finished recapping a TS-23b chassis last week. Before you inject a signal, try to get the raster correct first. Adjust the ion trap magnet first for maximum brightness. Then you can adjust the centering/ focus coil. You may have to loosen the nut at the base of the focus coil mount. Be careful not to hit the neck of the crt with this adjustment. There should be some kind of cushioning inside the focus coil. Did you replace the selenium rectifiers? Did you use a schematic for the TS-23b ? Other Motorola chassis are wired differently.
Ed

[Electronic M]

Once the raster looks good play with fine tuning and adjacent channels to see if you can get decent video strength and sound...

If the set uses intercarrier sound circuit topology, and has no video and weak sound and uses a germanium diode for a video detector that can be a symptom of it's failure.

If you have a purpose built RF and video test pattern generator and you can't get RF on any channel you can try injecting video at any plate or grid between the video detector and the CRT. If you don't have a purpose built generator, but do have a video source connect a pair of .1uF 600 volt caps in series with the hot and shield leads of the video source (to help prevent frying your source) cable and try injecting near the output of the video detector and first video amp stage.

Have you cleaned the tuner contacts?...If they are dirty they can prevent signal flow from getting past them.
Are you familiar with what a non horizontally and vertically synced picture looks like? ( horizontal and diagonal stripes)....it looks like garbage to the unfamiliar, but tweaking the hold controls (and sometimes coarse horizontal osc freq) will often get good picture out of an unsynchronized mess.

[rwilson]

Thanks for the replies. Yes on the TS-23B and it does have diodes now and a 20 ohm dropping resistor added in series with the fuse resistor.
This is a photo with the B&K 1077B test pattern which we have all seen.
It actually looks better than I thought but I still don't know what the problem is.
This is the best I could make it using the rear controls.

[Electronic M]

Originally Posted by rwilson

Thanks for the replies. Yes on the TS-23B and it does have diodes now and a 20 ohm dropping resistor added in series with the fuse resistor.
This is a photo with the B&K 1077B test pattern which we have all seen.
It actually looks better than I thought but I still don't know what the problem is.
This is the best I could make it using the rear controls.

Horizontal looks decent depending on the mask in the cabinet.
Vertical is pretty far off. If height and V linearity don't fix it, double check you replaced the caps with the right values (and avoided fudging close but wrong values) and check vertical stage resistors are within labeled tolerance...It is most likely a resistor issue.

Is the B&K feeding RF or video to it?

[rwilson]

Also I see now that vertical linearity is also at max. Maybe that's a clue.
I tested all of the tubes and changed out several but have not swapped any out yet.

[EdKozk2]

Make sure you replaced capacitor (C-70 , Riders) or (C-68 , Sams). I found the one in my set under the pictured filament transformer. The capacitor is a 0.05 mfd @ 600v.

[old_coot88]

Looks like a gawdawful power supply ripple. You mentioned a floating ground. Is there a chance you coulda misgrounded one of the filter caps?

[rwilson]

EdKozk2 you were spot on. I had missed the cap behind the filament transformer. I changed it out and the screen was full. Thanks for your help.

The circle is still not very round. I did have one filter cap tied to chassis ground that I made before I was aware of the floating ground. I changed it but did not see any change. But its a lot better now. Thanks for everyones help so far.
I will try and make some adjustments to see if that helps.

[EdKozk2]

Looks much better. Are you testing your set with an isolation transformer? I ask because when this set with the floating ground is plugged directly into the 120vac mains you may encounter a few issues. If you are using a converter box or VCR / DVD the set may end up with a very washed out picture. Very light in one section and dark in another. The hum may also mute the sound somewhat. The source could be a 60 cycle sine wave hum getting into the video signal. If this happens try reversing the plug in the outlet. Touching the converter box coax and antenna terminals at the same time may also give you a shock. Grounding issues, I wear rubber / cloth gloves.
Ed

[rwilson]

Ed, yes I am using a isolation transformer. I will try it without and see what happens.

[bandersen]

Looking good. Keep in mind the picture should not will the screen vertically. Looks like you have a little too much height and the linearity is off.

Also the horizontal linearity is off a bit. Have you tried adjusting the hor. lin. control ? Can also be effected by the horizontal output and damper tubes.

Here a thread on my 12K2 I restored a few years ago.
http://www.videokarma.org/showthread.php?t=251132

[rwilson]

Bob, I have watched all of your videos on the 12K2 and learned a lot watching them. Thanks for making them available. The one you did really looked nice after you were finished.

I have too much width and the adjustment lever will not bring it where I want it. Also the sound and picture do are not the best at the same fine tuning setting.

I'm having a lot of fun playing with all of this and learning a lot. I still have the Halolight set my dad bought in 1953 to start next. I thought this 12 inch set might be a little easier to start with.

Bob

[bandersen]

Thanks, it was a fun project.

The width doesn't look that far off to me. It should fill the screen left to right. Width controls typically have very little effect and are meant for fine tweaking.