Motorola roundie

[Yamamaya42]

Originally Posted by old_tv_nut

To repeat: you cannot conclude that there is a bad component somewhere until you do the alignment. Then if you still have trouble, you can conclude there is a bad component somewhere.

Exactly, as many have been trying to get across for some time now, you are merely chasing a phantoms of your own creation.

[timmy]

how does a color afc become out of alignment when nothing was ever touched, it would have to be a component failure so doing an afc alignment which I cannot do in its entirety so weather the oscillator is running or not I still have to search for a bad component. If the oscillator is not running again bad resistor or cap I can’t see turning the oscillator slug to get the oscillator running again when it will probably stop again because of a bad part. The only thing I found in the oscillator is a 680ohm resistor checking at 741ohms.

[timmy]

I have read several posts on other forums and it’s been said if the xtal is changed then the oscillator coil will more then likely have to be tweaked to get the color back so when I tried the xtal and got color I did bearly get the slug to move and turned it half way in and out and made no difference I didn’t want to go to far so I put it back where it was.

[Yamamaya42]

You have an uncanny propensity to ignore repeated advice from those with more experience on said given subject.
Which is ultimately your prerogative, but will highly likely doom you to repeated failure after failure.
Example,
old_tv_nut is highly experienced in the TV field, and has been VERY involved with it's development since it's early days, he is a valuable source of knowledge for vintage TVs and the history there of.

Electronic M is also a very good source of TV restoration knowledge, he KNOWS what he is talking about, as does bandersen , dtvmcdonald, Username1.
I can go on and on.

The statement still apples .

“To repeat: you cannot conclude that there is a bad component somewhere until you do the alignment. Then if you still have trouble, you can conclude there is a bad component somewhere.” -old_tv_nut

Until this is done, you will forever go in circles chasing your tail.
The fact that you ever got color to work at all on it before, was simply wildest stroke of luck.
Things had to line up PERFECTLY for color to lock in, but due to the age of parts, and non alignment, factors like temperature, humidity, percentage of tube health and who knows how many other factors left you a VERY narrow window where it would work correctly.

Again, the correct alignment would have made this more stable.
And it's very unlikely by what you were describing that the old crystal was bad, the description of getting rainbow stripes sometimes , and other times, not is a symptom of a de-tuned circuit.


I gave you an example of what it looks like when the crystal is NOT working.
https://imgur.com/9HcgQcz


if it's running
https://imgur.com/m0IePGv

First
get the cores unstuck

Second, do the color AFC alignment.

THEN, if that fails
Third
look for the fault.

But it's your set, you can do what you want.

[old_tv_nut]

If you can now turn the slug, you can do the alignment. You only need a color signal source and a voltmeter.

At the point where the procedure says "Connect the Vertical Input of a scope to point H..." you do not have to do that. Instead, view the picture and try turning the hue control from end to end to verify that correct hue is in the center. If it is not, then touch up A19 to center it.

[timmy]

Originally Posted by old_tv_nut

If you can now turn the slug, you can do the alignment. You only need a color signal source and a voltmeter.

At the point where the procedure says "Connect the Vertical Input of a scope to point H..." you do not have to do that. Instead, view the picture and try turning the hue control from end to end to verify that correct hue is in the center. If it is not, then touch up A19 to center it.

I assume you are referring to the slug in A18 that’s the one that’s stuck. How much voltage should I see on pin 1 of the phase detector if the oscillator is running or does it even matter if not running there won’t be any voltage.

[Username1]

Normally I don't comment on this because I find it quite ridiculous, but here it goes.....
I see Timmy replaced a 680 Ohm resistor in the Osc. Circuit because it measured
741 Ohms.... I looked around that circuit and I assume it's R179. That resistor
is in the current path, not critical to signal. If you do the tolerance math
(Tolerance = ((Measured Value - Expected Value)/Expected Value) X 100)
you get 8.970% - That makes this resistor out of tolerance only if it's 4th
band is gold. I think most cathode resistors are of no 4th band color,
making them 20%, even if it was a silver band that's 10% and it
should be fine in that part of the circuit. I find it useless and a
waste of money and time to replace that resistor with 1%
resistors, yet I see it over and over again here. Not to
mention, you replaced a resistor most likely within
tolerance for that part of the circuit.

One thing I also find to be of poor practice is to suspect a part that you do not have
the ability to test, like a small value capacitor that is in the signal path IE Not a
decoupling cap. like one in the cathode circuit to ground. Each time anyone
replaces small value caps in the signal path, YES you are de-tuning that
circuit to some degree. This tv has had dozens of parts replaced in
the IF and other sections just a few weeks ago. Potentially
de-tuning each section where parts were replaced.

Another thing to think about is the manufacture of this tv. I know none of you think
about this - so I'll give you something to think about.... Parts like resistors are ordered
by the thousands, lets say they ordered 500 new 680 Ohm resistors for delivery
for the run from Mon - Wed. and all those resistors measured between 690 and
710 Ohms. They certainly did not measure each before installing them, best
case they did spot checks. Each TV Worked as it rolled off the assembly line....
Then for Thurs & Fri they got 680 Ohm resistors that were all 710 - 770 Ohms
and all those sets worked because they went into the current path and simply
were not critical to the tv working & producing a nice picture..... Then think
about this same thing happening to each and every part in the tv. The
engineers set tolerances and the TV worked because part tolerances
happen in manufacturing all the time. And I'm sure that 1960's
parts manufacturing had part variations all over the place....


So back to the tv. Timmy said once he replaced the crystal he had color locked but
the colors were wrong.... So my questions Was the tv on it's side? or was it sitting
on it's legs on the floor..? When it got it's color locked, what happened when you
adjusted the tint & color knobs...? When you turn on a tv show like "All in the Family"
and you get a big head on the screen, Like a closeup of Archie, or Edith, even if the
color is wrong, is it uniform across their entire face? I use All In The Family, as an
example because in that era of tv, they often used facial closeups quite often....

At this time, I think you guys need to determine if the color is locked, as in the
Osc. is at the correct frequency & stable, and if it's possibly out of phase, as
in the tint is out of range...... So Timmy how about a few screen pics
with the tv sitting on it's legs on the floor, and with a close up of
Archie, Edith or some other show where we can easily see
what is going on.... Several Pics, Please also comment
on if the camera is truly representing what's on the
screen. Also Maybe you could post pics of the
far left, Center & far right of the tint control...
Identify those pics separately so we know
they are of tint control range.....
Like maybe put each set of
pics in a different post.

Thanks.....
Have a wonderful day!




.

[timmy]

I did the AFC I get 5 volts so the oscillator is running but got no color bars with the bar gen just like rainbows. And I had put the old xtal back in with this test but when the new xtal was in the color I got on the tv was the same with the set on legs or on the side.

[Yamamaya42]

Originally Posted by timmy

I assume you are referring to the slug in A18 that’s the one that’s stuck. How much voltage should I see on pin 1 of the phase detector if the oscillator is running or does it even matter if not running there won’t be any voltage.

No, A19 the phase detector, with tint at center, adjust till color is correct, Faces IE reds and greens and such.

@ Username1
the ones I suggested he replace with 1% was the matched pair of 470k
I prefer 1% because the price difference between 1%-5% and so on is pretty much insignificant, especially when resistors are bought in large combo packs of 300+ of multi values. the value i need is always on hand

[timmy]

a19 adjust if I get voltage from the phase detect meaning oscillator is running to correct the colors. I can adjust these colors with the bar generator

[timmy]

Something else must be going on here because A19 one full turn in and out did nothing just rainbow colors

[timmy]

So just running this tv for short times it has gotten much worse the voltages at the 2 330pf are now gone zero volts and along with rainbows the top of screen turns black and then comes back. Any adjustments made on A19 is back where it was so now I’m stumped.

[Yamamaya42]

That was braced on you mentioning you had color lock, if you do NOT, then A18 has to be tuned until you get lock.

This is NOT the right way to do it, but should get you by.
If you have no color lock, rainbow colors or in some extremes no color, tune A18 until you get lock, and find the sweet spot, tune up and down finding where it locks in and out and tune it in the center of the range that it locks, after that is done, you should not have to touch it again, unless something changes in the set, sometimes changing a tube can cause this to be upset and need adjusting.

THEN

once A18 is set to it's center of it's effective range ( no matter what crystal is in there )

you set tint control to center position, and adjust A19 until colors look correct, red/green, flesh-tones and so on.

[timmy]

Ok well I need to find a good way to free up A18 without damaging it. When I changed the xtal I had mostly red and it locked but now no more red with either xtal.

[timmy]

Well I don’t have a choice now I have to cut the connections on the coil and pull it out because my plastic tool was slipping in the hole and upon a closer look it looks like the slug has 2 cracks in it. I have a new slug but it’s a spec longer then what it looks like the one in there. My guess is the longer slug should work.