Motorola roundie

[timmy]

Originally Posted by Yamamaya42

Once again, you will be likely finding yourself up the creek without a paddle here (an oscilloscope), with very little to guide you in the right direction, for all you know, the IF could be acting up again, and annihilating the color sync information before it can be processed.

A good start that is IF you had a scope, would be to check the beat pattern going into V22, chroma phase detector, fed from the burst amp, this is what locks in the ref osc.

I can’t see how the IF could be the culprit it’s been fine I still have a good b&w picture still it gradually got harder for the color to sync up now it’s gone

[Yamamaya42]

Originally Posted by timmy

I can’t see how the IF could be the culprit it’s been fine I still have a good b&w picture still it gradually got harder for the color to sync up now it’s gone

https://hackaday.com/2018/01/18/know...ideo-waveform/



It's exactly what happened with with my CTC-16XL, I had color with direct input video, but not from tuner, a messed up IF WILL BLOCK color, cause the timings getting to the color circuit will be distorted, in my case, the 4.5 mhz trap was WAY out of tune, blocking all color, leaving a perfect BW screen, the IF on mine is still not fully right, but works well enough.

But yes, a borked IF can distort the colorburst signal timing, leaving just a BW screen, this can be tested by once again removing the 3rd If, and putting in direct video at test point B , as you have done in the past, if you see no color, then it's the color circuits, if you do, then is a problem before the color circuits.

[timmy]

Originally Posted by Yamamaya42

https://hackaday.com/2018/01/18/know...ideo-waveform/



It's exactly what happened with with my CTC-16XL, I had color with direct input video, but not from tuner, a messed up IF WILL BLOCK color, cause the timings getting to the color circuit will be distorted, in my case, the 4.5 mhz trap was WAY out of tune, blocking all color, leaving a perfect BW screen, the IF on mine is still not fully right, but works well enough.

But yes, a borked IF can distort the colorburst signal timing, leaving just a BW screen, this can be tested by once again removing the 3rd If, and putting in direct video at test point B , as you have done in the past, if you see no color, then it's the color circuits, if you do, then is a problem before the color circuits.

The 41.25 trap was the big problem I had originally and never had to mess with the IF in the first place so I can try to tweak the trap and see.

[Yamamaya42]

It would be more advantageous to try to feed in video at point B first, with the 3rd IF removed, to try and localize the area of fault before you tweak anything.

[timmy]

I just turned it on cold and the color came in but if I turn the channel selector and back to 3 no color sync

[Electronic M]

Originally Posted by timmy

I just turned it on cold and the color came in but if I turn the channel selector and back to 3 no color sync

Get out the freeze spray!

[Username1]

Does the line go from 12 - to - 6 ? Vertical line top to bottom? That's the transition
from Horizontal output tube to damper.... You know about that right....
Might not be much to worry about.......


.

[timmy]

Any ideas how to get a slug to move when they don’t move using a plastic diddle stick ?

[Yamamaya42]

Originally Posted by timmy

Any ideas how to get a slug to move when they don’t move using a plastic diddle stick ?

Depends on the reason for it being stuck, if it's stuck due to wax or something of that nature, warming the ferrite core may get it free, but if the core is broken, or the tube it's in has degraded and swollen, there is no option other than to replace it.

As bandersen pointed out on U-tube, the older type brass metal ones were better.

[timmy]

Originally Posted by Yamamaya42

Depends on the reason for it being stuck, if it's stuck due to wax or something of that nature, warming the ferrite core may get it free, but if the core is broken, or the tube it's in has degraded and swollen, there is no option other than to replace it.

As bandersen pointed out on U-tube, the older type brass metal ones were better.

The core is good it just looks like possible wax but with a plastic adjuster there’s only so much it can take before the adjuster breaks

[timmy]

The only way I can see to heat the core is with a pencil type soldering iron that would fit the hole it’s screwed into. I was going to bearly tweak the oscillator

[Yamamaya42]

What I have done before is taken the correct size allen wrench, and put it in the stuck core and heated the allen wrench, and applied heat to the stuck core indirectly, but by no means should one ever try to turn it with the allen wrench that will break it, only the plastic alignment tool.

[timmy]

No I wouldn’t use a metal Allen wrench I know they break like a cracker

[Electronic M]

On coils with thicker guage wire like H linearity coils I've heated the coil by connecting it to a D cell battery.

The fine guage ones like color and IF the Allen wrench heater sounds clever... Maybe add some heatsink compound to the end in the slug to improve thermal conduction to the slug.

[zeno]

The 41.25 & 4.5 traps are the only things you should tweak BUT
flag your stick to go BACK to start.......
I doubt it but if the set has AFT or AFC turn it OFF. That can cause
a channel to not FT on channel change. My rule is always turn OFF any
auto color / AFT while trouble shooting.

73 Zeno
LFOD !