Motorola roundie

[reeferman]

It has been many decades, and failing memory, but here goes.
In the shop we used to generically use this method. Set must be warm.
Ground the grid of the 3.58 reactance tube. If you get multi-color stripes (a must either way) on a TV picture or low input color bars, adjust reactance coil for single color per vertical bar or the color picture syncs.
If that doesn't work try the same with the 3.58 tube and its output xfmr to the demods.
It's been a long time.
Good luck.

[timmy]

What’s the easiest way to tell if the 3.58 crystal is bad ? Or going bad. Turn on got color bars let it warm up shut it off turn back on color is fine.

[old_tv_nut]

Depending on the chassis, a bad crystal may give no color or a greenish picture. If you have color bars, the crystal is fine.

[doogie812]

This one is easy. Locate the burst amp on the tube chart. Remove it. Adjust the oscillator coil (the one closest to the chroma oscillator without the shield) to zero beat the color. Reinstall the burst amp tube. Regardless of shifty drifties this will keep you out of trouble for a while.

[Yamamaya42]

again if you go through the color AFC alignment procedure listed in the SAMs, it may solve the problem, but if it does not, you have parts in the color circuitry that have drifted too far out of tolerance, and temperature is having a direct impact on this.

[timmy]

So I’m going to get the set on it’s side and take the metal cover off the bottom to gain access to under the chassis so I have 1st&2nd chroma bandpass burst amp and chroma sync phase det which one maybe responsible for color bars not syncing as I’m going to look for bad resistors since getting done with this set the color was fine so it’s probably a resistor that drifted alittle to far out.

[Yamamaya42]

Since you are dealing with a temperature related issue on an older set, it may be advantageous to go with higher testing parameters when checking the resistors, especially when newer higher tol ones are much cheaper and very available, example, if the part is a 20%, reject and replace if it's out at 15% with a new 2% part, and if it's a 10%, reject and replace if it's like 7% or worse, or thereabouts.
Reason being, the more the old parts age, the more they will slowly drift out of tolerance and tend to be affected by temperature, the more newer parts placed, the less you will have to deal with later.

[zeno]

This may help or hurt. Been 50 yrs & if wrong please correct.

Burst amp pulls the color sync off the horz blanking pedistal. It on the " back porch " and 8 cycles. Hoz osc pulses gives it the narrow grab, the
burst tube amps it & passes it to the 3.58 for sync.
No burst gives barber pole color or no color. The burst adj can "center" the
tint range.
Dead 3.58 gives a classic pink & green on many sets (RCA), no color,
wrong colors, barber pole. Xtals do go bad but not often. If the
XTAL has a third GND wire use that type.

enuf
Zeno

[timmy]

Well it’s got to the point that warming it up is not working so its more then likely it’s a resistor or maybe even a tube I will have to check them I also thought that maybe it’s the alignment but i got a really good b&w picture and when the color locks the picture is perfect or maybe a weak signal coming from the trap to the video detector. Don’t really know yet.

[old_coot88]

Originally Posted by zeno

This may help or hurt. Been 50 yrs & if wrong please correct.

No burst gives barber pole color or no color.

Been about 55 yrs for me, but I remember it vividly: House call, Zenith console, no color. Subbed tubes, tried color killer, nada. Shopped the set and it was the burst tube, a 6EW6. I had missed it. No excuse, just dumb. Boss wasn't amused. Funny how one remembers one's *bleep*-ups with such clarity.

[timmy]

Was is the pole color referring to color bars up and down or left to right. I have left to right.

[zeno]

Originally Posted by timmy

Was is the pole color referring to color bars up and down or left to right. I have left to right.

Kinda hard to describe but usually color bars rolling up. Can be many
bars or just a few rolling by slow. L-R says purity but if B&W is good
thats not it.
Find & check the hoz out sample lines. They go to burst, hoz blanking,
AGC & conv. Can cause some odd problems.

Zeno

[Yamamaya42]

What it should look like w/o color sync lock

https://imgur.com/m0IePGv
https://imgur.com/Tvyc044

From when i was fixing color on my CTC-16XL

https://imgur.com/9HcgQcz
with the ref crystal disconnected.

[timmy]

Originally Posted by Yamamaya42

What it should look like w/o color sync lock

https://imgur.com/m0IePGv
https://imgur.com/Tvyc044

From when i was fixing color on my CTC-16XL

https://imgur.com/9HcgQcz
with the ref crystal disconnected.

Yup that’s what I’m getting

[timmy]

So far I’m not finding any out of tolerance resistors I double checked tubes also so this loss of color lock definitely seems like a bad resistor what part of this circuit takes the biggest beating. I didn’t get into the afc as the color was fine it just started to lose sync and gradually got worse like a resistor so I don’t believe the afc would have anything to do with this it was not touched. I have a new crystal but it’s being said that having color bars the xtal is good so I didn’t try it.