TV Zenith Solid-state 70's - Page 6 - Videokarma.org TV - Video

zeno · #76 04-14-2015, 07:29 AM

Quote:

Originally Posted by Dreamsbeard

I redid the convergence with the colors turned off (and did a pretty good job of it). It improved things a bit, but when I put the colors back I am still getting blue and red fringing and that affect the picture quality. At the moment it's like I'm watching TV with a coating of vaseline on it.

I am sure CC can give a very good picture, but it seems I'm going to need some help to get there.

When you have a pattern on are all 3 color lines very sharp or are any
blurry ?
When a CRT gets a little weak you get get what looks like the
convergence off. If its that it will improve with lower bright &
contrast . Also gets better with warm-up.
It may be time to get rid of that blob since that may be affecting
things & needs fixing anyways.
Also do you have a manual ??

73 Zeno

Jon A. · #77 04-14-2015, 12:10 PM

Yeah, I was wondering how this CRT would do on your tester. This set has probably seen a lot of use, like mine it has mung around the HV anode cap. Nevertheless, it produces a nice picture.

Dreamsbeard · #78 04-14-2015, 06:51 PM

Quote:

Originally Posted by Electronic M

What is happening is the sharp monochrome contrast transition is being interpreted by the chroma circuits as a color signal. To fix this (assuming a good combo of fine tune and chroma level don't fix it) you will need to re-align the chroma bandpass amp and or the RF/IF system...Or you could just live with it (as I've done on a couple of sets until I can get an alignment rig together and practice).

No way I'm going to leave this as is haha. What would be required to do this?

Dreamsbeard · #79 04-14-2015, 07:00 PM

Quote:

Originally Posted by zeno

When you have a pattern on are all 3 color lines very sharp or are any
blurry ?
When a CRT gets a little weak you get get what looks like the
convergence off. If its that it will improve with lower bright &
contrast . Also gets better with warm-up.
It may be time to get rid of that blob since that may be affecting
things & needs fixing anyways.
Also do you have a manual ??

73 Zeno

Well the CRT was a bit on the low side but still in the green (ever so slightly) but tracking wasn't to good so I decided to clean and balance it , and that brought the guns back quite a bit , so I assume it's not a problem of bad CRT.

I posted two pictures of the pattern I use for convergence. First one (black and white) is with brightness and contrast lowered and "color" set to none. The next one is about 20 sec later with color , brightness and contrast set up for an adequate picture, but not on the overkill side, only good enough for viewing.

As you can see, the lines that appeared converged on the first picture lights up like a chrismas tree! haha.

I do not have a manual as of right now but I think Marco does...

Electronic M · #80 04-14-2015, 07:14 PM

Quote:

Originally Posted by Dreamsbeard

No way I'm going to leave this as is haha. What would be required to do this?

Correctly working and calibrated sweep generator, marker generator, oscilloscope, the correct probes for them, alignment diddle sticks, the factory or sam's manual for the set with the alignment procedure....Add patience, time to practice, and a guinea pig set to practice on if you have not done alignment before.

If that is Marco's set ask him to email you the schematic. I'm the one that scanned it and emailed it to him. I don't have the alignment info for that chassis....

Dreamsbeard · #81 04-14-2015, 07:26 PM

Quote:

Originally Posted by Electronic M

Correctly working and calibrated sweep generator, marker generator, oscilloscope, the correct probes for them, alignment diddle sticks, the factory or sam's manual for the set with the alignment procedure....Add patience, time to practice, and a guinea pig set to practice on if you have not done alignment before.

If that is Marco's set ask him to email you the schematic. I'm the one that scanned it and emailed it to him. I don't have the alignment info for that chassis....

Well, damn...you could have said that I needed 1.21 gigawatt to get it going and I wouldn't be less floored haha. Sounds like an expensive proposition, and I suppose there is no simple way around it?

Jon A. · #82 04-14-2015, 07:44 PM

Quote:

Originally Posted by Dreamsbeard

Well, damn...you could have said that I needed 1.21 gigawatt to get it going and I wouldn't be less floored haha. Sounds like an expensive proposition, and I suppose there is no simple way around it?

Getting the diagnostic/repair equipment needed for this hobby is a never-ending quest, or so it seems. Once you have a workbench that looks like an airplane cockpit, you should be just about set.

Electronic M · #83 04-14-2015, 09:06 PM

Quote:

Originally Posted by Dreamsbeard

Well, damn...you could have said that I needed 1.21 gigawatt to get it going and I wouldn't be less floored haha. Sounds like an expensive proposition, and I suppose there is no simple way around it?

If you have the right gear for FM radio alignment, or the right test pattern (and a lotta balls) you might be able to adjust the chroma band pass amp (I've contemplated trying it by eye on a 60's RCA clone).
As for RF/IF alignment in theory one possibly might be able to pull it off by eye with a multi-burst pattern and possibly a scope....But it is very hard to do properly, and you'll likely just make things worse.

I've been collecting equipment on the cheap for years, and I think I might have enough gear to pull it off, but all my gear is cheap junk so I need to verify it all works then select a 'practice victim'....And I don't have the time presently.

It ain't as hard as catching lightning for some techs here who have done it, and still have the equipment from TV shops they once worked for, but picking it up from scratch takes some motivation and cash (or a lot of time searching if your as cheap as me).

Marco-nix · #84 04-15-2015, 06:31 AM

Quote:

Originally Posted by Electronic M

Correctly working and calibrated sweep generator, marker generator, oscilloscope, the correct probes for them, alignment diddle sticks, the factory or sam's manual for the set with the alignment procedure....Add patience, time to practice, and a guinea pig set to practice on if you have not done alignment before.

If that is Marco's set ask him to email you the schematic. I'm the one that scanned it and emailed it to him. I don't have the alignment info for that chassis....

Yes Electronic M this set was mine.. yesterday night I emailed him what you given to me ...

DaveWM · #85 04-18-2015, 11:32 PM

alignment is something of an art as well as a science. As mentioned the need for calibrated test equipment, the correct procedure for making terminations of test gear, correct load blocks, correct bias settings, correct lead dress, all comes into play, even then its not for the faint of heart.

Just moving your hands around can upset the look of the bandpass on a scope, even tube jockeying can effect it. Unless you know someone has been messing with the coils its really best to leave it alone or as mentioned start with a set you don't care about. That way when you strip the IF thread out of the forms, or crack a slug from using the wrong tool, or do some other serious damage, at least its not a big loss.

With practice you can get start to get the feel of it, but generally its not needed on anything made from the 1960's on up, again unless it was tampered with or a major part (like a coil) had to be replaced.

there are lots of you tube videos out there that you can check out, just to see what others have done.

zeno · #86 04-19-2015, 10:13 AM

Alignment is simple. Just change the IF module, its
all in there. Only has a 3.58 trap in the video off board.
Also has a CTA ( cross talk adjust) pot where the color gets
stripped off the composite.
Interesting thing is the 3.58 trap is where the bright,
sharp & contrast are also the H&V blanking.
Remember that blob ?????????

73 Zeno

Dreamsbeard · #87 05-12-2015, 04:04 PM

Quote:

Originally Posted by zeno

Alignment is simple. Just change the IF module, its
all in there. Only has a 3.58 trap in the video off board.
Also has a CTA ( cross talk adjust) pot where the color gets
stripped off the composite.
Interesting thing is the 3.58 trap is where the bright,
sharp & contrast are also the H&V blanking.
Remember that blob ?????????

73 Zeno

So, the IF module could be aligned, but it would also be possible to simply change it. What I could do, if anyone has a spare IF module, is that I could replace mine, and then ship the faulty module to anyone that would be interested to restore it. I took a picture of the chassis with what I think is the IF module. Could I remove the module without having to pull the chassis?

As I was chatting with Jon.A , he suggested that the dent that I have in the CRT face glass could compromise the integrity of the tube. What do you guys think? Do you think it might be dangerous to operate the TV?

Thanks!

Findm-Keepm · #88 05-12-2015, 05:30 PM

There are screws and plug-in wires on the bottom of the chassis that have to be removed. PTS, Zenith and others rebuilt the IF modules for the duramodule sets. Finding them should be fairly easy - they were often replaced, although not bad, when any video gripe came about. Yes, 90% of the time, the IF module was good, and the B+ cap, a connection, or an IF injection lead from the tuner was at fault.

150- prefix for the IF module, IIRC. I don't have my CRSP handy to tell you the replacement matrix - i.e. which 150- ### IF module replaces what....

Cheers,

andy · #89 05-12-2015, 05:39 PM

...

Marco-nix · #90 05-13-2015, 06:53 AM

Quote:

Originally Posted by Dreamsbeard

As I was chatting with Jon.A , he suggested that the dent that I have in the CRT face glass could compromise the integrity of the tube. What do you guys think? Do you think it might be dangerous to operate the TV?

Thanks!

Oops! .. I had not seen this little spot (dent) on the picture tube .. but I already saw this kind of spot on many old televisions and this has never bothered TV operation ..