[QUOTE=Yamamaya42;3247041
A telltale sign of messed up IF is getting good BW but crappy or no color, why it does this is complicated, but it has to do with how they took the normal BW video standard and crammed color info into it and still had it compatible with older non color sets.

[/QUOTE]

It depends on what the actual IF response is on the malfunctioning TV. Generally (but see the service data first) the video carrier and color carrier are at or near the 50% amplitude point on the response curve; the 45.75MHz video carrier is there to compensate for how the unwanted sideband is filtered out at the transmitter, and the 42.17MHz chroma subcarrier point is placed there to minimize interference in the picture from the chroma information. The chroma bandpass circuits compensate for this falling response and have to be aligned with a special setup, basically the video carrier modulated by a frequency sweep at the chroma frequency range. If either or both of those carriers is significantly out of place, there are going to be problems with the picture.

Picture problems related to alignment usually end up as ghosting that changes with the fine tuning adjustment, weak or no color, excessive hue shift with fine tuning, or interference patterns in the picture, either from the sound carrier or 920kHz beat from the chroma carrier. These adjustments have to be done with test equipment, they cannot be done visually.

So agc when’s it’s turned ccw the pick gets dark and distorted then turned cw picture is stable and brighter, is this how agc is supposed to behave ?

Yes it is, read the instructions on how to set it in the SAMS, even though it only factors in with TV stations tuned in from an antenna, it will still have an effect when a signal is being fed in from a modulator, turning AGC will have a drastic effect on the video, this is normal, set it to a decent range.

The higher up cw the brighter the screen gets. At this point I don’t know anyone in my area that knows how to do an IF alignment on this Motorola so all can do is the impossible by trying different adjustments on this set one day I’ll give up or maybe I’ll get lucky I’m into now so I don’t have a choice . I could give up now and put it in a corner and let it get dusty or I could try. It wouldn’t be worth the cost of the equipment to do an alignment and I don’t know how many pieces of equipment it would take or be needed to get the job done.

Or, you can build the video amp and convert to direct input.

Or, just buy the equipment needed, and do the alignment. The Sam’s is on the ETF website and has the entire process. It’s not very involved, and actually pretty simple. Steps 1-4 should get you close, if you do it carefully a few times.

Get a perfect B&W picture, before screwing around with the color stuff. You can’t get good color until you get the B&W stuff right.

Randomly turning afjustments will just make everything worse.

This thread has gone on for 1200 or so posts. We’re going in circles now. This is, TBH, getting stupid.

I disagree. It looks like very bad purity.

Yes it is bad purity since nothing is setup.

I already have a near perfect B&W picture.

[QUOTE=trinescope;324704
Picture problems related to alignment usually end up as ghosting that changes with the fine tuning adjustment, weak or no color, excessive hue shift with fine tuning, or interference patterns in the picture, either from the sound carrier or 920kHz beat from the chroma carrier. These adjustments have to be done with test equipment, they cannot be done visually.[/QUOTE]

Ditto, well said. IF alignment rarely goes way out without HELP.
Once I changed an IF transformer in a GE. I eyeballed thet one.
The last Emerson TV's seemed to have alignment probs but they were
such POS's we never dealt with it. And had a big Admiral that an alleged
TV man got to with a diddle stick. We couldnt fix it & sent it to Admiral
of Boston. Even they couldnt fix it.

73 Zeno:smoke:

I have a really good B&W picture and it don’t turn to ghosting moving the fine tune it gets snowy. With the IF out there is probably no way I could set up the color I have a dot bar generator it shows dots and line pattern and shows color bars the colors in the bars seem to be off a bit but clearly shows each color it does show all from the bar dot generator on screen. At this point I didn’t try to set the color up. I would think the color has to use the IF ???

This is just one of the pictures posted that I have seen with color in it, I'm very sure that color is working with direct video input.

Sent from my VS501 using Tapatalk

Should I be able to set up the color with the IF the way it is ???

Been saying that for years. You can NOT have a good color TV til you have
a great B&W.
Turn the color all the way down & concentrate on the B&W.
BTW the pix of the set on its side looks good. Purity is way off but thats
normal on its side. Looks to have good B&W and color. Maybe a complete
" by the book" CRT set up is in order before anything else.

Zeno

That pick is from injected video the other pic of the dog in a previous post is from the tuner and bad IF.