colors change

[timmy]

what tube would most likely be responsible for colors changing.some yellows would change to an aqua and brown would change to a tan color. and when images move from up down or side to side they sometimes change. would this be a sync problem.an image that is all red sometimes the top half is red and the bottom is alot less red in color. this is the motorola that is kicking my ass with problems.

[Electronic M]

It could be that your color osc. is loosing synch. I have a Silvertone that looses color synch sometimes and has diagonal color stripes going diagonally across a perfect monochrone picture.

[Don Lindsly]

Check purity and B & W for entire screen area. Make sure the B & W looks good over the entire screen, at all brightness levels.

Make sure the CRT guns all track, before digging into the color circuits. Then put a color bar generator on it and see if the bars are consistent from top to bottom.

[Jeffhs]

I had a 1964 Silvertone color roundie, like Electronic M's, that would lose color sync occasionally; however, on mine the color stripes were horizontal, not diagonal. I was able to get the color to lock by rapidly turning the tint control from one end of its rotation to the other. Never did find the actual cause of the trouble. All I knew was that the 3.58-MHz color burst oscillator was out of sync with the station signal; however, why rotating the tint control would bring it back in sync is a mystery to me even now, almost 40 years later. That set had several other problems besides, such as a hum bar that would float upwards through the picture, bad convergence I never did get right (I didn't have a generator at the time), and so on. Finally had to junk it when a tube socket broke out of a PC board.

[oobamamalik]

If I add dye to my plants, will the colors change color?

[timmy]

Originally Posted by Don Lindsly

Check purity and B & W for entire screen area. Make sure the B & W looks good over the entire screen, at all brightness levels.

Make sure the CRT guns all track, before digging into the color circuits. Then put a color bar generator on it and see if the bars are consistent from top to bottom.

hi mr lindsly i have been communicating with bob gatarz from new jersey on a possible flyback problem on a ets908 chassis motorola he will be sending you a message. this set has low hv,14kv bright down, 11kv bright up and the center coil gets very hot, not the donut, the coil in the center of the donut and i have run out of options aside from thinking the fly is bad. there is no burning smell just very hot after about an hour.cathode current should be 105 on each tube and together should be 210ma but its at 238ma and cannot get it lower.do you have any suggestions as to where i should look at this point.caps were changed, tubes check out, and did the tests to get the hv to rise and it wont. cap off 6bk4,focus tube out, crt plug off nothing will raise the hv.i had twisted lines on the left screen and found a resistor in the yoke that was bad and changed it and cured the lines but this resistor gets HOT and the old one showed it got hot as well. i dont know if this yoke resistor has anything to do with whats going on with the hv. thank you

[old_tv_nut]

Originally Posted by timmy

what tube would most likely be responsible for colors changing.some yellows would change to an aqua and brown would change to a tan color. and when images move from up down or side to side they sometimes change. would this be a sync problem.an image that is all red sometimes the top half is red and the bottom is alot less red in color. this is the motorola that is kicking my ass with problems.

This could be a burst gate problem - try turning the horizontal hold slightly either way (the picture should shift slightly left and right) and see if the color changes. If the burst gate lets some of the red picture content into the color sync circuit, it could upset the colors.

[timmy]

i tried that thinking it might be that but no it didnt work. i got other things going on with this headache set, resistor in the yoke, low hv, and what ever else, its making me crazy.

[Phil Nelson]

Here is a pic from an old RCA color service book that illustrates classic loss of color sync. The "RGB" bands are a giveaway:



The bands can be thin or wide, and they can move at different speeds (or not at all). I struggled with a color sync problem on my CT-100:



The next pic shows a color bar pattern (yes, really) when the sync was totally out of whack:



Those are examples of crazy bad color sync. As old_tv_nut suggests, your problem may result from more subtle causes.

Don mentioned purity, and a problem with that can create broad areas of wrong color, not so much in horizontal bands. The next two photos show the result of moving my CTC-11 across a room and turning it 90 degrees from its previous orientation. (The cornfield should not be red, and Dorothy's mouth should not be green!)





Degaussing quickly cured that problem.

I don't have a specific suggestion for you, but perhaps these examples will help you identify what's going on, or at least rule out some issues.

Phil Nelson

[ctc17]

A properly working HV circuit is essential for everything else to work. Flyback pluses are used for the color circuit, deflection, sync, convergence etc. If you have moved the yoke or anything on the neck the set requires purity setup

[timmy]

well i did the set up all over again but i posted in another spot that the set was off all night and i took the chassis out to check something and upon putting back the anode it arcs every time i get neat the crt to put it back on and this is crazy its like its grounding somewhere and with the rec tube and crt socket out and nothing near the anode wire this is what its doing and i never noticed it befor . may be this is something to do with the low hv. anyone ever hear about this happening?

[Jeffhs]

For ctc17:

Wow! I had no idea the high voltage played such an important and vital role in the operation of CRT-based color TVs. For example, I knew that the horizontal sync is extremely critical in color TV; if the hold control is off by even a hair's breadth it can kill the color in no time flat, even though the monochrome picture will not be affected. However, I did not know about all the other problems low or no HV can cause in a CRT-based color set. No high voltage will kill the raster; that much I knew, but all the other things you mentioned that can go haywire in an older color set when the HV acts up are nothing short of amazing, to me anyhow.

[mstaton]

You need to ground the anode(set off and unplugged) before removing the chassis. The CRT can hold the HV for days or weeks. The CRT acts like a capacitor. This is normal. If you don't, it will arc when you reinstall the anode lead.

[ctc17]

Sarcasm?

Flyback pulses often drive the noise inverter circuit and keyed AGC. In Zenith most of the convergence board is fed by the flyback.
Boost voltage is used for the vertical, screen voltages and many other in a color set.

In a way the horizontal output circuit and flyback is the heart of the tv and its where everything begins.

[zenith2134]

I totally concur about the importance of proper horizontal output operation for the rest of the set....The horizontal drive is what runs the HV and fly and in turn, the flyback derives many crucial voltage points even low-voltage ones such as sound in a solid-state set. Sometimes focus voltage is derived via a divider. One time I was working on a 68 GE color tabletop and the horiz. oscillator tube was bad causing the HOT to overload and preventing HV from coming up. I didn't think to check the osc. and assumed the fly was bad. Once I rang it to test it, I learned this lesson.