Did you ever figure out why? Perhaps wrong value resistors? Perhaps installed wrong? Cold solder joint or solder blobs? Many things can go wrong in what seems like a simple part replacement. :scratch2:

Recheck your work.

jr

Right resistors in the right place

Good Morning & Happy Tofu Turkey & Gluten Free Dinner Rolls Day to Everyone!

Timmy, I think for the first order of business, you should turn that detector diode around
& see if it makes a difference, It's just a signal diode, no 2 amps of current
running through it so you can't explode anything. If there ain't no improvement,
then just put it back....

Also back onto the look of the picture, I think you should also check the color killer
knob & with a so called picture on the tv, you should turn that control back & forth
& see what you get.... Turn the color knob up to about 1/3 & let it sit there....
You know what the color killer does, on a off channel with snow on the screen
a working color killer will make the snow B&W, Color Killer set wrong will
leave it with color snow.... It will also Not let the color circuits run on
B&W tv shows, so there might be odd color effects mixed in with a
picture that should be B&W. Your current Negative looking picture
looks to me like an open delay line, resulting in only color signal
being displayed on the screen, only here it's not color....
So with just turning the color killer knob lets see
if there is any effect there.... If no effect at all
then turn it fully counter clock wise & let it
sit there, so it's off, or set it to where it
was originally if you think no one ever
turned it and let it sit there....

Also I asked about the coils in that area, and you said that the IF Coils were already
checked, but that is not the coils I'm interested in....

I'm wondering about everything in the signal path of the Detector on-to the video
amp & output. L7 - L14, You don't have to take them out because they are all
low ohm, just test each series run of 3, you can see it amounts to about 6
ohms for each run of 3. Check R59 - L16, L17, R65, follow the signal
path through the delay line, (Check it too) & follow the signal path
to V5, are the voltages there close to what they should be? Does
the Brightness & Contrast knobs work properly? When you
have that negative looking picture on the screen,
does the Bright & Contrast have normal looking
effects on the screen?


.

As for the color killer pot it works and the negative picture get color snow on the edges when turned up and brightness works as it should and the contrast does make some difference with the video as it is. The detector diode when I first removed it and tried another I marked the cathode end and made sure I put it back right and tried another yesterday and made no difference. I know what you mean about color snow I had that in the beginning but no more and really don’t know why. I have snow noise in audio and minimal snow on screen but no color snow like it once had. I did inject video again at point B and gave it some color and that worked out good. I listed the video amp and output on a previous page. This is injected video at test point B and just a quick addition of color so would this rule out any problems with the resistors and coils and delay line.

Once again, it’s pretty clear that there is a serious IF issue in your set, which is causing most of your video problems, and without the equipment and knowledge to adjust and debug it, the chances of getting it working is bleak, so unless you can find someone local to help you with it, your best way forward is to build a small video amp to boost the composite level to the 5v that the set expects at test point B, and rig for direct A/V input until some future point that you can find someone who can help you get the front end IF/ tuner input working the way is should.

That picture attachment of injected video at TP B is really nice & looks better than
the earlier pics.... I don't see any problems with the circuit components from
that point on. I guess it's still forward of that point. That leaves IF &
Detector, anything before TP B. This tv & it's problems sure are
illusive.... The negative looking picture bugs me. I think a number
of years ago someone on here had a 21xx55, I forget now the
full chassis, it was the first 21" with the chassis from the
15GP22, and if I recall correctly that person had a
negative or very faint picture, & he was thinking
it was a problem around the detector diode.
Anyway I don't recall it all that well, & Can't
find it. You may just have to go through
each little nook & cranny of the IF
strip & recheck everything you
already did..... I don't have a
good idea on where to go now.

I never had to do a full alignment on a TV IF, so you might just
have to invest in a scope & alignment marker generator to
figure this one out..... The thing is, how cold it have got
so far off to look like it does now?

.

So if I never get this IF strip right to produce good video is there another way to get an RF signal from a cable line to put it into another device to produce the RF to put on test point B for video and just bypass the IF itself. Like if a flat panel tv had a separate IF board wire that in with its own power source don’t know if this is possible but it’s a thought. Or perhaps one of those mini pocket tvs using the output to test point B.

Any cheap used VCR you can find will work, preferably with remote, it really does not have to play tapes, but you will be hard pressed finding ones to don't , what is important is the tuning section of it.
Just one example of many.. https://tinyurl.com/348uu9p5


It can be used to tune into what ever station needed, and output A/V to the TV, however the video will have to be boosted a bit to 5v with a simple amp like.

https://www.electronicsforu.com/elec...ideo-amplifier

which works on 5v and can be adjusted by setting the resistor networks.

I would only need a channel 3 and I could change the channel by using the cable box. What about a b&w pocket tv like the Sony fd20 I have 2 of these. Here is the schematic for the tv I have if I cut number 4 from the rest of the circuit and place it on test point B it should give me video sound I would get later note the 4.5 volts at v3 IF.

Timmy
At this point I really think you need to invest in a MODERN analyst such
as the Sencore VA48 or VA62. That will give you a stable known source
that was built for your sets era. A scope is nice but an analyst
helps with other projects & do more than trace & show freq.

This is long distance servicing. VERY hard to do. A lot of us that
spent time in the biz fixin 10's of thousands of TV's could spend a
few mns looking , twisting & observing a set & know where to go.
You have stuck it out well & the next one will be easy.

BTW vid det diodes are usually in a can. Often the can has two parts
& if you pull the top half off the diode is there. You can always nip one end
of the diode & hang a new one in on the bottom for test.

73 Zeno:smoke:
LFOD !

+1 a Sencore analyst or B&K 1077 analyst and a scope are things to have if you own more than 2 vintage TVs that you plan to maintain.
A daily driven tube TV is going to fail every 12 months give or take 6...If you get tricky troubles every 3rd time, the time you save with good equipment will pay for that equipment and it's storage several times over.

A cheap used VCR is the best choice for setting it up for direct AV input, cause as mentioned, they are still very easy to find, and have good stable tuners and output composite A/V, that Sony portable would not be a good choice cause it would need major adapting to be used, the schematic shown does not list any signal levels, but only the DC voltages at those points.

It should be easy enough to find a VCR, build the video amp, and adapt to A/V input until a future point you have the equipment or can get someone to help repair the IF section.

Using that small tv it wouldn’t take that much adapting it would need to be grounded to the chassis probably a single wire to get the sound and another singly wire to test point B and wire in the power source to the switch and make sure it’s tuned to channel 3 and forget the rest. Mount it on a small board out of the way. The antenna input would be setup on the tv board. Again just another thought.

Too many unknown factors with that, what is the peak to peak output at that point on that video buffer chip? You need 5v, is it inverted or not inverted?

The Sony schematic gives no clues as what the video signal is, only hints of a 5v vertical blanking pulse at q402.

The idea of this seems much more trouble than it's worth over a VCR.

Cable boxes do sometimes have composite A/V output that can be used for this such a thing, but you also need to input test patterns for convergence, so a VCR'S tuner is more flexible.

Well I do have the complete schematic for this Sony. I figured if it were that easy to get video from a DVD player I thought I could use the IF from that little tv and just input the cable to it and get video and maybe work out any other things after.

DVD players & VCRs have composite level video output, (positive 1v ptp), however, what that Sony has at that buffer chip is an unknown factor.
By adding that simple video amp listed before to boost it to 5v it should give it what the TV needs.

So are you saying that using the little amp to boost to 5v and putting the IF from the Sony into it would it work is that what your saying?

What is unknown about the Sony, is what the peak-to-peak voltage of the video signal out of the buffer chip is, and if it is positive or inverted, chances are that one is positive, one is inverted (11,12) but w/o an oscilloscope to look and see what they are, this is a risk factor that it may or may not work due to the unknown factors of not really knowing what is being put out of the IC, for example, if you knew that it was putting out .5v positive peak-to-peak, then you could build an amp with enough gain to boost it to 5v.

On the other hand, a DVD/VCR always has an output of 1v peak-to-peak, thus you make a amp with a gain of +5, more or less.

Ok but I’m looking for the cable input I don’t need vcr or dvd I just want to be able to watch regular tv and I would use the cable box remote change the channel. So in the end I could always try it there’s nothing I have to do to the set to try except try one of those wires or just take it from the 3rd IF and see what happens.

I'd just build the little 5V video amp and feed it with an RCA composite cable. That way I could plug a VCR in or any other device I want. If you find a good line level output point on the Sony later if there's an RCA composite video cable coming out of the moto you can plug it into the Sony later.

Here’s the full schematic notice after going along to 2 transistors it shows 5v p-p well it’s not clear enough

I have the same schematic, that does not look like a video signal there at the collector of Q402, but looks more like a blanking pulse, from q401 or d301, which will only mess up the video out .

Then what about taking it directly from v3 ? Although I don’t see any kind of diode

This Motorola has the thermistor is it absolutely needed if it were taken out and jumped would this affect the transformer so many other color sets don’t have this thermistor and they survive. I put higher amp b+ diodes in so they should hold up from a heavy jolt.

Normally the thermistor circuit is added in color TV if the auto degaussing is built in, not sure why it's in your set.

Would it hurt anything if I jumped the thermistor being it’s connected to line voltage anyway just to rule out this low voltage v3 pin 7-8 should be 210v but it’s only 162 v and r54 is new 4.7k 5 watt. V1-2 pins 7-8 should be 210v 100v but it’s 198v and 96v the 275v is only 256v 19v difference

Doing that won't likely get you anywhere, those voltages are close enough for things to be working.

If the thermistor was a problem, you would see large voltage drop across it after it was heated up, and sweep problems.
What you should see across it, is a large spike in voltage as it comes on when cold, that then lowers to a few volts when it warms.

If you really feel the need to try it out, try carefully jumping it after the set has been on for a little bit, but it's pretty much certain at this point, doing so will make no difference in the tuning problem that you have. :(

Ok I jumped it and voltages did come up and stayed up it wasn’t much but I find the images I get on screen get more vivid and more contrast when I parallel another resistor to r54 in an attempt to raise the voltage on 7-8 of v3 clearly the voltage is to low there it should be 210v it makes no sense new resistor by itself voltage is to low.

I know things are not working right but v1-2 the voltages are right now I got 210v on v3 pin 7-8 but pin 2 should be zero but I’m getting .9 -1.4 -2.0 fluctuating and pin 3 should be 2.5 I’m getting 4.5.

As it has been said many times, do not take the voltages shown on SAMS as an absolute, variances of 10-15% or even more are normal, also these were taken with a VTVM on a working well aligned set, yours is out of alignment, and you have a digital meter, all of these will alter voltage readings to a wide degree.

This picture is from the sets own tuner so if the IF was out I would not get this and how I got this is rather odd and it may narrow down where a problem could be but I don’t know yet. A jumper between pin 1 v3 to what looks like L9 with a .01 in between.

Being the jumper is on pin 1 of v3 is not exactly bypassing v3 itself otherwise if I put the jumper on pin 2 then I think that would be bypassing v3 maybe a cap at v3 ? No color or vertical is setup at all.

Bypassing things like a Christmas tree won't really help much with the underlying issue that the IF needs alignment to get the video clearly from the tuner to the 1st video amp.

evident that it's blocking color.

The color is turned down along with the hue and no color controls are set and obviously the video is coming from v1 and v2 and somewhat v3 this is all coming from the tuner no subber.

Why is it that when the color intensity knob is turned up alittle it then looks like it needs to be fine tuned.

Herringbone pattern in video.
Which is what I tried to point out yesterday.
http://www.videokarma.org/attachment...3&d=1670356881

All color is essentially being blocked in the tuner/ IF because the response curve is so far off.

Turn up the color, and the patterns show up, turn it down, they vanish, but put in video at test point B, and you see color, meaning that chroma bandpass is OK, and the corruption is in the IF, as been very evident for some time now.

Do review this thread, and how carefully and methodically he has been aligning the CT-100.
http://www.videokarma.org/showthread...=274959&page=9

There is just no getting around that sometimes it has to be done on these sets.

Even though this set has problems v3 pins 7-8 should have 210v but only has 160v this voltage is not going to gain 50v simply by having this set working there’s more going on here.

I'll try to explain this again the best way I can, of all the tube circuits in the TV, the IF is the MOST sensitive and hardest to deal with, and unlike most other areas, you can NOT measure voltages in the area with a normal digital meter, because as soon as you hook it up, it will alter the circuit and change what you are trying to read. You MUST use a VTVM, or a FET VOM, otherwise you will get false readings due to the added load from the meter in the circuit.

The voltages im referring to is the 210v that should be present at pin 8 v3 that comes right off of the 275v tap with a 4.7k resistor to drop it. Pin 8 is 50v short of what it should be.

That still does not change that a digital meter will give inaccurate readings in this situation with a active RF circuit, you must use a use a VTVM, or a FET VOM, to get correct readings.