Zenith 1979 Chromacolor II - No color

[Palinurus]

I recently bought a 1979 Zenith Chromacolor II (chassis 25KC45, model K2518M). When I tested it out it had no color, except for a bit of yellow here and there. I adjusted the grey scale and the yellow went away, but I'm still trying to troubleshoot the color problem. Was there a factory reset button on these TV's? I'd like to pursue the simplest possible solutions first.

I'm thinking that I may need another chroma module. Mine is numbered 9-89-H. I watched a Youtube video of a restoration of a 1977 CCII which had a module that looked very similar to mine. Were some of these parts interchangeable, despite the different numbers? Any help would be greatly appreciated. Thanks.

[Jeffhs]

Originally Posted by Palinurus

I recently bought a 1979 Zenith Chromacolor II (chassis 25KC45, model K2518M). When I tested it out it had no color, except for a bit of yellow here and there. I adjusted the grey scale and the yellow went away, but I'm still trying to troubleshoot the color problem. Was there a factory reset button on these TV's? I'd like to pursue the simplest possible solutions first.

I'm thinking that I may need another chroma module. Mine is numbered 9-89-H. I watched a Youtube video of a restoration of a 1977 CCII which had a module that looked very similar to mine. Were some of these parts interchangeable, despite the different numbers? Any help would be greatly appreciated. Thanks.

I wouldn't replace any components in your TV just yet. Older color TVs have a circuit called the "color killer", which cuts off the color circuits during b&w programs (this was when TV stations still broadcast black and white shows; the killer is all but unnecessary today, as all network TV shows are broadcast in color now). My best guess is the color killer control on your TV is set too high, causing the killer to work overtime, so to speak, that is, cutting off the color circuits whether or not it needs to. I would readjust the color killer control by first tuning your set to a blank channel, then adjusting the killer until the color just disappears from the snow on the screen. If this doesn't work, try replacing the color killer tube, as it may be weak or dead.

[zeno]

99% of "no color" symptom will be the 9-86-## color board. Be sure to
get the right -## ( letters dont matter). The 9-89 only has the video out & 3 color drivers. This all assumes correct fine tuning & a good source.
If you trouble shoot the 9-86 odds are its one of the IC's. Both were common & used in other brands. The zenith PN's for IC's starts 221-### ( sometimes with -## at end).
While you are in there both the 9-89 & the 9-88-## have ceramic resistor
packs, flat white & black. They always get cold joints so solder them up
before putting together.

BTW Problems with the 4 lead cap A.K.A. safety cap do NOT apply to
your set.

Good luck & stay well
73 Zeno
LFOD !

[old_coot88]

Zeno, did any ss sets still have a color killer adjust? I don't remember ever seeing any. Or at least never had occasion to look for it.

[Electronic M]

Originally Posted by old_coot88

Zeno, did any ss sets still have a color killer adjust? I don't remember ever seeing any. Or at least never had occasion to look for it.

Take what jeffhs says with a grain of salt. He doesn't even seem to realize the 1979 Zenith being discussed here is solid state, and that they stopped making tube hybrid color in 1975...

[Palinurus]

Thanks, Jeffhs. The model I have is a solid state, but I'll look into it.

[Palinurus]

Thanks, Zeno. I see a 9-89-R for sale for $20, but it doesn't appear to have the IC that mine does. I'm hesitant to order it. Is the IC the black card-like piece attached to the module? The 9-89-R doesn't appear to have one. My IC is numbered "Zenith 105-110" with another number E-181-7833. It's also referred to as "IC 1201 THICK FILM" in the diagram pasted inside the TV.

[JohnCT]

Originally Posted by Palinurus

Thanks, Zeno. I see a 9-89-R for sale for $20, but it doesn't appear to have the IC that mine does. I'm hesitant to order it. Is the IC the black card-like piece attached to the module? The 9-89-R doesn't appear to have one. My IC is numbered "Zenith 105-110" with another number E-181-7833. It's also referred to as "IC 1201 THICK FILM" in the diagram pasted inside the TV.

No, the 89 module is the kine driver. If that's bad, you'll have bad grey scale. EDIT: I see where Zeno advised soldering the thick film ICs on the 88 and 89 for general maintenance, not to fix the no color condition. Good idea. Use enough heat and I'd add some flux to it. The solder on those gets crusty and doesn't like to reflow easily.

As Zeno said, it's the 86 board right above it.

There are two ICs on that board, but most problems are either bad connections on the ICs, bad connections between the module and the chassis connectors, or adjustment. Every once in a while we'd see a bad IC.

If you have an early module, the ICs are not mounted in a socket, they're mounted in individual pins. Remove the ICs, clean the pins with fine sandpaper or pen eraser (the leads are probably black with oxide), clean with alcohol, and put the chips back. If the color comes back, I'd remove the socket pins and solder the chips directly to the board. You can always buy standard 16 pin sockets and replace those crappy pin sockets. Zenith eventually soldered down the ICs in later versions and in rebuilds.

There are 4 adjustments on the 86 module, one of them is color killer. See if you can find a SAMs - I don't remember the adjustments any more..

There is also burst kill switch on the module used to set the 3.58 osc that gets dirty. Clean that as well.

I believe there might also be one or two electrolytics on those boards. At this age, they're likely to be iffy.

EDIT #2: I seem to recall there were several suffix versions of that board (maybe 6 or more), but they all subbed into two classes. I don't remember the numbers but they look very similar but won't interchange. If you do put the wrong one in, no harm will be caused.



John

[Palinurus]

Originally Posted by JohnCT

No, the 89 module is the kine driver. If that's bad, you'll have bad grey scale. EDIT: I see where Zeno advised soldering the thick film ICs. Good idea. Use enough heat and I'd add some flux to it. The solder on those gets crusty and doesn't like to reflow easily.

As Zeno said, it's the 86 board right above it.

There are two ICs on that board, but most problems are either bad connections on the ICs, bad connections between the module and the chassis connectors, or adjustment. Every once in a while we'd see a bad IC.

If you have an early module, the ICs are not mounted in a socket, they're mounted in individual pins. Remove the ICs, clean the pins with fine sandpaper or pen eraser (the leads are probably black with oxide), clean with alcohol, and put the chips back. If the color comes back, I'd remove the socket pins and solder the chips directly to the board. You can always buy standard 16 pin sockets and replace those crappy pin sockets. Zenith eventually soldered down the ICs in later versions and in rebuilds.

There are 4 adjustments on the 86 module, one of them is color killer. See if you can find a SAMs - I don't remember the adjustments any more..

There is also burst kill switch on the module used to set the 3.58 osc that gets dirty. Clean that as well.

I believe there might also be one or two electrolytics on those boards. At this age, they're likely to be iffy.

EDIT #2: I seem to recall there were several suffix versions of that board (maybe 6 or more), but they all subbed into two classes. I don't remember the numbers but they look very similar but won't interchange. If you do put the wrong one in, no harm will be caused.



John

Thanks. That really cleared a lot up for me. I think the easiest thing to do is to first get a hold of a SAMS and to check out the color killer and the burst kill switch. The module that I have is a 9-86-02E. Though it wouldn't interchange with other versions, would the IC's be the same? Or are different IC's part of the reason why they won't interchange? I noticed that one of the IC's on my module is numbered 8701H, i.e. it doesn't have the 221 prefix that Zeno referred to. That may to evidence that it was replaced at one time.

I greatly appreciate your help.

[JohnCT]

Originally Posted by Palinurus

The module that I have is a 9-86-02E. Though it wouldn't interchange with other versions, would the IC's be the same?

There are several suffixs that will sub the -02. I *think* any sub that is even number will work, but I'm not positive. There are people I can call that will likely remember.

In the meantime, some of this is coming back to me. Check the 24V regulator carefully for output. The regulator is a TO-220 mounted on the front of the chassis near the breaker. It has to be exactly 24v on the emitter.

Also, there are some electrolytics in the 24V feed on the back of the chassis that cause havoc. These are radials and are physically large. Check or just replace any of them.

Lastly, I recall a problem with an open coil causing loss of 24V to the chroma module. I'm pretty sure it's terminal W9.

And again, pull the ICs and clean the pins and reinstall - that fixed most of them. And I do believe that all versions of the -86 used the same ICs, even if the boards didn't sub. There's an outside chance I may have one. If I do, it's yours.

I'm pretty sure I still have the Zenith service data for those years. I'll check tomorrow when I get to work.

John

EDIT: if you need to replace a capacitor or inductor on the back of the chassis, do a clip and loop method. The components are soldered deep into the back of the module contacts, and the less stress put on the module contacts at this age, the better.

[zeno]

Originally Posted by old_coot88

Zeno, did any ss sets still have a color killer adjust? I don't remember ever seeing any. Or at least never had occasion to look for it.

All I remember was ACC ( auto color control ) & APC (auto phase control) &
a set-up switch.ACC can kill the color. Also on hybrids.

[Palinurus]

Originally Posted by JohnCT

There are several suffixs that will sub the -02. I *think* any sub that is even number will work, but I'm not positive. There are people I can call that will likely remember.

In the meantime, some of this is coming back to me. Check the 24V regulator carefully for output. The regulator is a TO-220 mounted on the front of the chassis near the breaker. It has to be exactly 24v on the emitter.

Also, there are some electrolytics in the 24V feed on the back of the chassis that cause havoc. These are radials and are physically large. Check or just replace any of them.

Lastly, I recall a problem with an open coil causing loss of 24V to the chroma module. I'm pretty sure it's terminal W9.

And again, pull the ICs and clean the pins and reinstall - that fixed most of them. And I do believe that all versions of the -86 used the same ICs, even if the boards didn't sub. There's an outside chance I may have one. If I do, it's yours.

I'm pretty sure I still have the Zenith service data for those years. I'll check tomorrow when I get to work.

John

EDIT: if you need to replace a capacitor or inductor on the back of the chassis, do a clip and loop method. The components are soldered deep into the back of the module contacts, and the less stress put on the module contacts at this age, the better.

I had to ordered some solder wick to remove the two IC's from the module, so I'll have to set this project aside for a week or two. I did check the regulator and came up with 23.7 volts with a multi-meter. I don't know whether that's close enough to 24v but if cleaning the IC's doesn't work I'll change the capacitors as well. Are the IC's for these old TV sets hard to come by? If so, and you have a couple I'd be glad to cover the postage if you were to send them. Once again, thanks for all your help.

[mr_fixer]

If it turns out that the module is bad, don't worry I and others have spares if you need them.

[Palinurus]

Thanks, Mr. Fixer. If cleaning the IC's don't work out I might take you up on your offer. Though apparently there were different versions of the 9-86 modules, not all of which were interchangeable.

[JohnCT]

Originally Posted by Palinurus

I had to ordered some solder wick to remove the two IC's from the module, so I'll have to set this project aside for a week or two. I did check the regulator and came up with 23.7 volts with a multi-meter.

Close enough.

...but if cleaning the IC's doesn't work I'll change the capacitors as well. Are the IC's for these old TV sets hard to come by? If so, and you have a couple I'd be glad to cover the postage if you were to send them. Once again, thanks for all your help.

If your ICs are soldered in, then cleaning won't help. That advice is for those 86 boards that use those crappy individual pins for sockets. I think the K series might have been the last vertical chassis Zenith, and later ones eliminated the sockets entirely (constant socket issues), so if they're soldered in, the oxidized pins are not an issue.

Look for 24v on the 86 board directly, I believe it was W9 IIRC, but if not, there is definitely 24V on one of the pins. If it's not there, there's an open inductor on the back of the chassis.

I may have a board, and others here will have a complete board as well. These were not that much trouble where they would be in big demand. Most vertical chassis Zeniths had contact problems with the modules, not the modules themselves.

John