RCA CTC? Table top with rolling cart

[freakaftr8]

I have a raster and an image. Just no snow flipping through the channels. it seems odd.

The raster acts as if there is no AGC but the control obviously is working while watching my pattern generator.

I'm going to have a look at the sockets to the burst amp and demod tubes. Have a feeling something is going on here..

[freakaftr8]

Lol pardon my ignorance but where is the A16 coil exactly? I have the rca schematic but no sams..

Obviously I would think it's by the 3.58 burst osc.

[Yamamaya42]

Originally Posted by freakaftr8

Lol pardon my ignorance but where is the A16 coil exactly? I have the rca schematic but no sams..

Obviously I would think it's by the 3.58 burst osc.

you can get the SAMS here
https://www.earlytelevision.org/tv_s...color.html#rca


It's not just a matter of adjusting 1 coil, there are 3.

there is a color AFC setup procedure to go through to get the circuit to lock on correctly.
It's in the SAMs how to do it.

[freakaftr8]

Ok I'll attempt this tonight thanks for the link! I noticed that the horizontal oscillator L38 coil was slug was loose. Not tight like you would normally find.

[freakaftr8]

Well.. We have color! I had to turn A16 clockwise about 8 turns..
Go figure.

Oddly I still have so snow are white noise on dead channels.

[freakaftr8]

BTW, AGC is working, so is color killer. Oddly, the slug in A16 feels like its almost at it's end of travel. Could this be drifted components?

[Yamamaya42]

Originally Posted by freakaftr8

BTW, AGC is working, so is color killer. Oddly, the slug in A16 feels like its almost at it's end of travel. Could this be drifted components?

Yes, any number of out of spec resistors in the area can cause the freq to drift, to a lesser degree, the caps.
I had the same trouble with mine, getting the osc on the right freq, as I mentioned in my thread, almost all resistors on my color PCB had already been replaced by someone, ( not all of correct values ), I went and replaced many with 1% tol metal film ones.

[freakaftr8]

Yeah this is what I figured I am most likely going to check resistors around the circuit anyway. That may bring me to dial back on the coil When I find some out of spec that need to be replaced..

Another thing I noticed is that this TV seems to have a very soft picture, I mean it looks good it just doesn't pop like I had seen in other 16s.

It's the best way to describe it is like a watercolor painting.. The brightness is there it just doesn't have the vibrancy to it. This could be the CRT. If you remember green was just barely touching good on the tester. Although it seemed to have excellent tracking on all 3 guns.

[Yamamaya42]

Originally Posted by freakaftr8

Yeah this is what I figured I am most likely going to check resistors around the circuit anyway. That may bring me to dial back on the coil When I find some out of spec that need to be replaced..

Another thing I noticed is that this TV seems to have a very soft picture, I mean it looks good it just doesn't pop like I had seen in other 16s.

It's the best way to describe it is like a watercolor painting.. The brightness is there it just doesn't have the vibrancy to it. This could be the CRT. If you remember green was just barely touching good on the tester. Although it seemed to have excellent tracking on all 3 guns.

Remember, until you put real video on the screen ( fleshtones and such ) it's a bit hard to tell if a17 is set right ( affects the range of TINT) , not very easy to set with color-bars, unless you know EXACTLY what it should look like range wise on a good adjusted set. I had to touch mine up once I got a DVD source.

[freakaftr8]

I was running some video through it last night. Seems like fleshtones and color processing is spot on.

At 1st I noticed with the coil barely on peak, greens were not being processed correctly so I gave it a 1/2 turn more in and it popped in

[freakaftr8]

Just realized that video peak has no effect. There is a slight shadow to the right.. I wonder if a peaking coil is open. Going to look at the SAMS later.

[Yamamaya42]

Originally Posted by freakaftr8

Just realized that video peak has no effect. There is a slight shadow to the right.. I wonder if a peaking coil is open. Going to look at the SAMS later.

Video Peaking has nothing to do with a “peaking coil” to quote Electronic M...
VideoPeaking...it is basically a video treble control. It changes the level of the high frequency portion of the video. Lead dress of the CRT socket wiring and differences in video chain tubes and alignment will affect high frequency video. Peaking is a compensation to allow fairly uniform video detail.

The switch hangs off contrast control, and switches in/out various capacitor values.

if you had a peaking coil out, you would tend to lose luminance, and it did not look like that.

[freakaftr8]

So video peak has to do with the amount of "pop" contrast between the whites and colors in the background? I have to look again, but I thought it ascs more like a sharpness control.

[Electronic M]

Originally Posted by freakaftr8

So video peak has to do with the amount of "pop" contrast between the whites and colors in the background? I have to look again, but I thought it ascs more like a sharpness control.

Visually it can have a sharpness effect.

An important thing to have right to get the most out of good alignment/peaking is focus. If focus is less than razor sharp fine detail is lost in a spot size greater than the size of said detail bleeding it's edges into adjacent phosphor. If you take a basically working set with lousy focus and fix the focus that alone can unlock performance you weren't expecting.

Some peaking coils were wound on resistors in the 10k ohm ball park (they made for cheap forms with integrated leads. I haven't looked at the CTC16 recently enough to see if this is the case, but in some circus it is possible for the coil wire to go open and the resistor to still be okay...in some circuits it is possible for the video chain to limp along like that with reduced contrast, brightness, and or detail....Sam's should list peaking coil resistance (it is usually not more than 2 ohms) and there is no harm in taking a DMM in ohms mode to your peaking coils if you think one is bad.
Stuff like that I see wrong more often with 50's sets especially ones with those elliptical chalk blob peaking coils that RCA and Motorola liked.

[Kevin Kuehn]

If I recall correctly some manufactures called it a detail control, which probably makes more sense to most folks watching the set.