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  #31  
Old 08-29-2016, 06:29 AM
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Smearing as you describe is most always a weak crt in a solid state set.
steve
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  #32  
Old 08-29-2016, 06:38 AM
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Quote:
Originally Posted by rcaman View Post
Smearing as you describe is most always a weak crt in a solid state set.
steve
Can also occur if color level is too high, or fine-tuning is mis-adjusted.
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  #33  
Old 08-29-2016, 07:16 AM
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Did you take the parts off of the CRT while you were working?
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  #34  
Old 08-29-2016, 08:24 AM
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Yep all parts were taken off the CRT to remove the cateract. I marked their positions and put back as close as possible. I tried it this morning and now it seems like the blue horiz amp pot has developed a dead spot, exactly where it needs to be. Will have to continue on it later.
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  #35  
Old 08-29-2016, 09:57 AM
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Originally Posted by Electronic M View Post
Can also occur if color level is too high, or fine-tuning is mis-adjusted.
When it is a monochrome picture (intensity all the way down, or in a middle to low position) there is no smearing regardless of brightness setting. It doesn't bloom like a weak crt in monochrome set, but rather smear the colour way past where it should be. I wanted to make a photo this morning (this is really hard to describe but easy to photograph!) but issue with convergence pot came up and needs to be dealt with first.

Tube does test good on all three guns with good colour tracking and cutoff

Worst case I can use the new testing 25XP22 in my RCA ctc38 , the Motorola is a much nicer TV and deserves a good tube. The sharpness of the picture is wonderful.
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  #36  
Old 08-29-2016, 06:43 PM
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Originally Posted by TUD1 View Post
I find it interesting that these have to separate controls for tint. They have one wheel for tint, and a slider for hue.
I know that Moto tube sets had the separate tint control because of the super-simplified DC-coupled single tube chroma section, but I didn't remember one on the solid state sets.

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  #37  
Old 08-30-2016, 06:23 AM
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Smearing is almost always CRT. If it only the red & only
with the color turned up even more so BUT it should
also smear some on a hard driven B&W pix.
Only other thing is the 200V that feeds the 3 color output
transistors. If the 200V isnt clean you can get smearing
& a lot of other symptoms, often subtle. Check
any 'lytics on it.
For blue pot you can add a 2W resistor in series with it.
About half the value of the pot. This will move the setting
away from the bad spot. Then you can scare up a replacement.

73 Zeno
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  #38  
Old 08-30-2016, 09:01 AM
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Quote:
Originally Posted by zeno View Post
Smearing is almost always CRT. If it only the red & only
with the color turned up even more so BUT it should
also smear some on a hard driven B&W pix.
Only other thing is the 200V that feeds the 3 color output
transistors. If the 200V isnt clean you can get smearing
& a lot of other symptoms, often subtle. Check
any 'lytics on it.
For blue pot you can add a 2W resistor in series with it.
About half the value of the pot. This will move the setting
away from the bad spot. Then you can scare up a replacement.

73 Zeno
LFOD
It also does it on blue. The effect is stronger on blue than red, and it only smears to the right, the left edge is sharp. Actually it's interesting you mention the three video output transistors, their load resistors look a bit heat stressed, and this PCB has clearly seen some repairs in the past. I did a bunch of re-soldering and repaired a trace on it but changed no parts during the recap. I will check the supply voltage and all the voltages on those transistors, if one was saturating would it have a smearing effect?

Thanks for the advice regarding the blue pot, that should be enough to get me going!
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  #39  
Old 08-31-2016, 11:22 PM
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So as it turns out the 150 ohm blue pot was open in a couple spots. I found a 400 ohm pot in a junk zenith chassis and installed it. Convergence isn't perfect with the wrong value pot but it will do for now (see image). With the 150 ohm pot the right side of the picture looked a whole lot better.

Then I tried some tests to check the smearing. It's worst on blue, so I measured voltages on the collectors of the video output transistors. They are way low, blue was only 100 volts and red and green around 125. The collector load resistors quite charred. When I swapped the connections between colours the smearing changed colour to whichever gun was connected to the blue transistor. (Yes!)

I think the collector load resistors are way high in value, not sure what's the root cause of looking burned though. Thank goodness it isn't the tube! Will pick up some parts and keep digging!
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  #40  
Old 09-01-2016, 08:27 AM
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It's great to see one of these fine machines dialed in right. Loved to work on them, few that I saw.

Makes me want to dig out my 1972 Quasar (the last WID?) and swap the tuner, which took it out of service and got it buried..
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  #41  
Old 09-01-2016, 08:47 AM
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Originally Posted by DavGoodlin View Post
It's great to see one of these fine machines dialed in right. Loved to work on them, few that I saw.

Makes me want to dig out my 1972 Quasar (the last WID?) and swap the tuner, which took it out of service and got it buried..
Mine has quite a ways to go before it's dialled in right, the components seem less bulletproof than an RCA or Zenith of the era.

Is yours a console too? I think it's a worthy project, I am definitely enjoying mine.

Kind of makes me want to get some AR-3 speakers since the styling is so similar!

Last edited by maxhifi; 09-01-2016 at 08:53 AM.
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  #42  
Old 09-01-2016, 12:53 PM
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Mine is a TS938 dated 2M72 and very similar to the one RadioTVnut posted in the rectangular color, in the same walnuty legged cabinet.
Instead of the 4-5 tube hybrid, mine has a SS sweep section and switched power supply module that was tricky. It has a 2-button clicker remote and no selector knob but a preset channel drum behind the door with 18 positions, 6 were for UHF and 6 was not enough in this area believe it or not but I had a VCR on it.

It moved with me twice since I got it in the mid 80s and used it in my room until the VHF tuner crapped out. Ill post a link as I put a picture on VK somewhere but the ad below shows the general arrangement. Loved that advertising they used ;-) but the tuners, MEH - not quite a Zenith!

I think many of these survived into the 80s and 90s simply because the TV repairmen liked working on them and the customer thought the drawer was cool as S**T Quasar II WID TS938.jpg
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Last edited by DavGoodlin; 09-01-2016 at 01:04 PM. Reason: add pic
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  #43  
Old 09-02-2016, 12:28 AM
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I adjusted it to exaggerate what I called smearing. This image should be monochrome. The video output voltages seem find and the CRT checks firmly into good..

It seems like solid blocks of red or blue will smear, while green doesn't at all. Definitely most noticeable in high contrast scenes.

I can adjust it to be totally watchable and reduce this effect but then it comes back when the contrast of a scene is high and saturated colors are present. I.e. Text or brightly colored clothes.
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Last edited by maxhifi; 09-02-2016 at 01:42 AM.
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  #44  
Old 09-02-2016, 09:12 AM
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Its been a while since Ive had a problem like this but it IS similar to how mine would behave under high-contrast and never happened with green IIRC. My 25V-crt was good and balanced but not like new.

So, it may be a CRT fault that is bore out by how fast the blue and red need to cut off. The white parts of the picture occur when all three CRT grids are as positive, and cathodes as negative as they get. It is probably not a demodulator issue, but its after that stage is the R-Y and B-Y possibly "ringing " as opposed to switching. In bit parlance, it needs to be de-bounced.

One book that may offer insight is the Tab Book - Motorola Color Service Manual by Forest H Belt. Ill check and see if this is discussed...
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Last edited by DavGoodlin; 09-02-2016 at 09:18 AM.
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  #45  
Old 09-02-2016, 09:26 AM
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Quote:
Originally Posted by DavGoodlin View Post
Its been a while since Ive had a problem like this but it IS similar to how mine would behave under high-contrast and never happened with green IIRC. My 25V-crt was good and balanced but not like new.

So, it may be a CRT fault that is bore out by how fast the blue and red need to cut off. The white parts of the picture occur when all three CRT grids are as positive, and cathodes as negative as they get. It is probably not a demodulator issue, but its after that stage is the R-Y and B-Y possibly "ringing " as opposed to switching. In bit parlance, it needs to be de-bounced.

One book that may offer insight is the Tab Book - Motorola Color Service Manual by Forest H Belt. Ill check and see if this is discussed...
Thank you! I need to check eBay for that book! Also, I can add a bit more information now. The G1 voltage is derived from a voltage divider off 230V B+, with a 27k resistor in series with a 10k resistor. I woke up this morning and decided I had to check G1 voltage, and It is 0V. The 27k resistor must be open. Not sure how this is related to other problems, but I can't imagine it helps the CRT to work properly. Will try a new resistor after work (no time for working on TVs this morning!)
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