Help Understanding ACC

[old_tv_nut]

Originally Posted by TinCanAlley

I'll do ACC with the color bars tomorrow. I am also going to hook up the scope to check the waveforms noted in the APC adjustment as I messed with that one by mistake. I'm assuming that when it says "check for proper keyed rainbow waveforms" they mean with the color bars displayed?

The particular waveforms you should get depend on what kind of color bars you have. The instructions are referring to a "keyed rainbow" or "gated rainbow" pattern that has 10 vertical bars of color with black inbetween. Is that what you have? I am disappointed that pictures of this pattern can no longer easily be found online. I've attached a couple of pages from the RCA Color Pict-O-Guide, which you can find at https://www.worldradiohistory.com/AR...Guide-1964.pdf

But really, if you know what the pattern is supposed to look like, you can just see if it's correct on the screen and checking the waveforms is not necessary.

[TinCanAlley]

I know for certain my generator doesn't create this pattern, but if I'm understanding things correctly, as long as the color generated pattern has the three basic colors displayed, I should see the waveforms as noted in the SM.

I have a couple different calibration discs and each has a bunch of different color bar patterns. If I display one of these patterns, is it the same to the TV and testing as if it came from a generator?

[TinCanAlley]

Originally Posted by old_tv_nut

The particular waveforms you should get depend on what kind of color bars you have. The instructions are referring to a "keyed rainbow" or "gated rainbow" pattern that has 10 vertical bars of color with black inbetween. Is that what you have? I am disappointed that pictures of this pattern can no longer easily be found online. I've attached a couple of pages from the RCA Color Pict-O-Guide, which you can find at https://www.worldradiohistory.com/AR...Guide-1964.pdf

But really, if you know what the pattern is supposed to look like, you can just see if it's correct on the screen and checking the waveforms is not necessary.

Wish I had more use for a bar generator. I found on on ebay that does the those bars and more, but can't justify spending on it for occasional use. The one I have not has been used about 5 times in 10 years or so.

[TinCanAlley]

Originally Posted by old_tv_nut

Any type of wire should be fine.

Is there a source for the type of wire used in older sets? I'm guessing it's a hybrid type of woven covering. Not quite plastic and not quite cloth. If I strip enough cover off the red tap wire, once soldered back on, it won't reach the "HI" connection. I'd really like to use the same color wire so it won't look out of place. I know the set is closed 99% of the time, but it would bother me.

If not, another option would be to strip enough off to solder on bare wire to length it, wrap that wound the post and then solder it. Won't be perfect, but should get the length to the point it reach to all three points of connection.

[old_tv_nut]

I'd be surprised if a solid-state era set had cloth wire, but somebody here should know better than me.

I'd think the usual would be PVC, and later solid-state chassis would have PVC with the temperature/fire rating printed on it (after UL tightened their requirements). Exceptions could be teflon-insulated wire in the high-voltage section.

[old_tv_nut]

Originally Posted by TinCanAlley

I know for certain my generator doesn't create this pattern, but if I'm understanding things correctly, as long as the color generated pattern has the three basic colors displayed, I should see the waveforms as noted in the SM.

I have a couple different calibration discs and each has a bunch of different color bar patterns. If I display one of these patterns, is it the same to the TV and testing as if it came from a generator?

The signal from a DVD will be even more accurate than from most service-grade test generators. Cheaper generators will have simple sync signals without all the FCC details like vertical equalizing pulses.

As long as the pattern has all three colors, you should SEE all three colors ON THE SCREEN, but if the pattern is not the one specified in the service manual, the waveforms will be different from the service manual.

[old_tv_nut]

Example: If you have the color bars shown in the lower left of the link below, you will have the luminance, B-Y, and R-Y waveforms shown in the upper left.

https://en.wikipedia.org/wiki/EBU_co...Barras_YUV.JPG

[TinCanAlley]

Originally Posted by old_tv_nut

I'd be surprised if a solid-state era set had cloth wire, but somebody here should know better than me.

I'd think the usual would be PVC, and later solid-state chassis would have PVC with the temperature/fire rating printed on it (after UL tightened their requirements). Exceptions could be teflon-insulated wire in the high-voltage section.

Maybe not cloth, but seems to have a braided covering. I found a seller of wire that matches pretty much in color and braiding, but it is 18ga and the original is 22ga. Also found a seller in Greece that has 100' of original 22ga wiring in all the colors, but it's over 500 delivered. Would be worth it if I had a business of restoring older sets and wanted to keep things original.

[TinCanAlley]

Originally Posted by old_tv_nut

The signal from a DVD will be even more accurate than from most service-grade test generators. Cheaper generators will have simple sync signals without all the FCC details like vertical equalizing pulses.

As long as the pattern has all three colors, you should SEE all three colors ON THE SCREEN, but if the pattern is not the one specified in the service manual, the waveforms will be different from the service manual.

I have a blu-ray player with composite output and will run it into the RF converter. This way I can use the Spears & Munsil calibration disc that has a number of different color bars. There is one that has all the color bars.

[old_tv_nut]

Originally Posted by TinCanAlley

Maybe not cloth, but seems to have a braided covering. I found a seller of wire that matches pretty much in color and braiding, but it is 18ga and the original is 22ga. Also found a seller in Greece that has 100' of original 22ga wiring in all the colors, but it's over 500 delivered. Would be worth it if I had a business of restoring older sets and wanted to keep things original.

Well, I learned something today!
This is a Zenith 25EC58? (Your first post said 2SEC58.)

[TinCanAlley]

Originally Posted by old_tv_nut

Well, I learned something today!
This is a Zenith 25EC58? (Your first post said 2SEC58.)

Yeah, typo on my part. Been fixed.

I was going to scope things today, but I got lazy and tried with the handheld Fnirsi unit. It couldn't display it correctly and I think it was all about setting the proper time/division. The user manual isn't much to speak of. I'm going to have to bring down my old school Tektronix tomorrow.

[TinCanAlley]

I know it's been a while since I've had the scope out, but I tried using it with the color bar generator to check the wave forms for R G and B, but what I get looks nothing like the ones in the SM. I set it for 10V/Div, 20us (even tried 10us), DC then AC coupling, calibrated 10x probe and used the external trigger from the generator (even tried without). I found the generator creates all the necessary bars for the keyed rainbow by pressing a button that gets rid of all the other parts at the bottom and leaves only full bars top to bottom.

The forms I get are stable, so I am locked in, but like I wrote above, the waveforms aren't even close to what the SM shows. I guess the handheld digital scope I tried was working as they looked the same.

I'm not chasing perfection, but I want to be as close as I can with old technology. I want to button it up knowing I've done all I can and it's as close to perfect as it can get.

[old_tv_nut]

"gets rid of all the other parts at the bottom and leaves only full bars top to bottom"

does not sound like keyed rainbow to me.

Sounds like primary and secondary bars (like SMPTE bars):
white, yellow, cyan, green, magenta, red, blue, black.

Is this what you had before "getting rid of the parts on the bottom?"

https://en.wikipedia.org/wiki/SMPTE_...Color_Bars.svg

[TinCanAlley]

Originally Posted by old_tv_nut

"gets rid of all the other parts at the bottom and leaves only full bars top to bottom"

does not sound like keyed rainbow to me.

Sounds like primary and secondary bars (like SMPTE bars):
white, yellow, cyan, green, magenta, red, blue, black.

Is this what you had before "getting rid of the parts on the bottom?"

https://en.wikipedia.org/wiki/SMPTE_...Color_Bars.svg

The bottom was a bit simpler than that, but yes. So this isn't a keyed rainbow pattern, darn. I found a generator on ebay that does the keyed rainbow, but not sure I want to add another generator to my collection for one purpose. I guess if it works, I can get rid of my Leader unit.

On another note, my tint is stuck in the poor control now. When it was working properly, it went from overly magenta, to more neutral and then to overly green. Each of those took about 1/3 of the pot travel, so to get from magenta to neutral, I had to move it at least 1/3 from fully counter clockwise. Now from fully counter clockwise it is magenta, then only a slight turn to neutral and another slight turn to green and the rest of the turn gets really green. The neutral section doesn't fully get rid of magenta or green, it's the best I can do to balance them.

I think I need to remove the subcarrier module and lift a leg of each capacitor and resistor for proper measurements. Then the same for the chroma module. Not sure about the coils and ICs on the boards (how to test or if they're even play a role in the tint adjustment).

[vol.2]

Originally Posted by TinCanAlley

The bottom was a bit simpler than that, but yes. So this isn't a keyed rainbow pattern, darn. I found a generator on ebay that does the keyed rainbow, but not sure I want to add another generator to my collection for one purpose. I guess if it works, I can get rid of my Leader unit.

The Heathkits do gated rainbow.