The reason why I ask is I tried the rf cable from the tv tuner and tried it on v2 and I was surprised that there was a picture present with not much contrast but it was very stable no vertical or horizontal issues so I’m looking into dirty tube socket or pin’s.

Why is it that some capacitors listed in sams don’t show voltage how do you know what voltage to put in.

Take a look at the voltages in the general area that it's hooked to in the schematic, add 100v, as a general rule.

1kv would be ok as well ?

As long as it can still fit in the same space the old one came from, and the farad rating is the same as the old, larger voltage really can't hurt.

So is it safe to say that even though injected video is stable and locked that there could still be a problem in the sync sep section knocking out the video path from the IF.

The 6HS8 is a dual function tube, even though the two sections share cathodes & G 1 and 2, the sections work independently, the sync sep section being on the right, AGC on the left, it is the video on pin 9 that is used for sync sep, and pulses on pins 3&6 for AGC.

I’m going to try that idea with the 9 volt battery and the pot what pin on v6 or where was the agc tap

So page 6 says to hook it up and see if it is over loaded so how is this supposed to work more 9v would clear it if it were over loaded I know it changes bias because it looks like it’s already overloaded I just need to completely rule this out for sure.

overloaded would be evident by a clipped wave or too high signal shown on the oscilloscope, but since you are going by what you see on the screen, things will be a bit different.

This may help to understand it a bit better, in this he drastically changes the AGC gain via external bias to a state over and under saturation,

https://www.youtube.com/watch?v=I1h5zNFvn_U

Good Morning:

If you really wanna see if your AGC is working, you could build a single transistor amplifier
4 resistors, total 47K on the outputs, 450K on the inputs, 18V supply, give you a
nice 5V P-P signal swing and feed a signal to it, and put it on your video in test point.
Without a scope you would have to go by what is on the screen. You got other tv's
so pick one put a signal on it and turn the AGC through it's range and watch the
screen......

Something like this:

https://www.electronics-tutorials.ws...ier/amp_2.html

You have to try and reach your required 5V P-P signal, so give it a try, you might
even have to use 2 transistors if you need to flip the signal, so keep that in mind....

I'm sure Yamamma can help out with it he seems to be able to find all kinds of goodies
online.

Once you get a proper signal your sync sep & AGC should work as expected....
With all the stuff & Time you spent up till now I think this may be a good step
to take..... Just keep in mind you will only see some voltages change, not
necessarily see a difference in picture etc. because AGC will not have an effect
on the picture because the signal is fed late in the system......

Poor signal would look washed out & poor H & V Lock. Overloaded pic would be very
high contrast, & noise on white lettering, possible H or V Lock on dark parts of the
picture resulting in a tearing look. I'm sure there are example pictures online....


.

I don’t know one minute it looks like it’s overloaded and then it looks like a weak signal.

I checked the voltages on v1 and 2 and they are spot on with the sets tuner being used and I seem to get more on screen using the tuner then the subber I really would think I would get more with the subber being it has a gain control. I don’t know what the difference is between the subber plug and the tuner plug really nothing yet the tuner has more activity.

Well, regardless of what tag they put on that subber, I would imagine that any adjustment
is to boost, or decrease output so as to change the level of signal available to the IF
section, not really the same thing as gain.....

Well, If you get something through the system directly from the TV's own tuner, that
is a major improvement, and big steps forward! And if that's the case, you should
definitely forget about feeding anything to the video test point, and work on the
battery AGC test point, and possibly even think about weather or not it's worth
the gamble of turning the trap coils to see if you can get more signal through.
But remember what was in that IF alignment video from this morning, you
have to remember each coil is peaked for a different frequency in the
full bandwidth that needs to make it through that section.... So
peaking one wrong will cause more problems....

Also if you are really getting a overloaded picture one minute, and a weak looking
picture the next, then you need to figure that one out.... Possible intermittent....
You may need to figure out how to clean the tube sockets & tube pins in a
really effective way..... Seems like you are getting closer to fixing this
one! And to do it before this thread hits 100 pages would also be
way-cool!!


.

At page 75 he needed to send Yamamaya42, you and a half-dozzen other people a gold watch for the time invested in this shit-show.

With the set using it’s own tuner there is a picture but it’s got no contrast and I’m able to adjust the horizontal so there is no lines and it’s a steady picture but it flickers in and out if I just touch the channel knob it will go out and I touch the knob and can get it back but there’s a lot of white because of no contrast so maybe there’s something going on with the tuner almost as if the tuner tubes are no good. And the battery bias test didn’t change anything that I was able to see.

If the tuner knob causes the picture to go in & out, then you need to focus on getting
good solid connections on each channel. Take the tuner apart, cover off, & use a wood
stick to poke around till you find the most sensitive parts and try and figure out
what is not making good contact. Don't worry so much about voltage checks
or replacing parts. Go after making the tuner solid when on a channel.

In our shop we use to clean all contacts with a gritty cleaner on Q tips,
probably not available any more, today I think the closest thing would
be the mildest valve grinding compound. You could use silver polish
or Ajax, something with really mild abrasive. But we had to remove
all of that stuff after it's use, so whatever you use be sure to use
small amounts, keep it confined, use Q tips, and remove it all.
Then after be sure to spray it with Tuner Cleaner so you
protect it from oxidation......

Be sure the switches are in good shape before moving on to see if it's a
loose component, ground, or tube socket. Clean tube sockets too.....





.

I would have to take the tuner out to reach all that I would have to clean and at the same time check resistors in there I think there are 7 resistors.

It's not recommended to do anything with the caps / resistors in the tuner, because to disturb them can cause more harm than good, even if they are out of tol.

What could be done is removal of the drum to allow better cleaning, but this is not easy to do as the spring clips holding it in on each end are a pain to get in and out, and very close attention to detail to all the parts on both ends of the shafts must be taken so that they go back in place.
But, once the drum is out, you have easy access to the spring contacts inside for cleaning and tightening if needed.

Ok got the tuner cleaned and checked resistors while in there a 220k was 260k and 4.7k was 5.6k the rest were good so I left them alone all I did was clean the spring contacts and the turret contacts and the spring contacts looked really used and there must have been old tuner spray that turned into sticky like molasses but got it cleaned. And yes clips and springs was fun but was not a problem for me it went back together just fine.

Ok tuner cleaned and ruled out no more flickering. So now even though it’s said not to take things to be right in sams like the voltages the Motorola schematic shows voltages higher then sams so the next thing is I really need to find out why the voltages are so low in this set even after 15 minute warm up.
275v=256v
190v=177v
145v=140v
640v=539v
770v=750v
Motorola shows much higher, these voltages are just to low something is not right. Pin 8 of v6 is supposed to be 230v but it’s 110v so if the main power supply voltages are low so is everything else. I had already checked out the power transformer and found it to be fine and 15 minutes is long enough for the thermistor to heat up and I had checked that as well IIRC it was 1 or 2 ohms. And all this is checked with 121v at the outlet.

Again, no 2 sets are alike, so you should never take the voltages listed in the SAMs as an absolute, variances of 5-10% is normal.

Try to differentiate between voltages that are all off by 20 percent and those that are off much more.
If all are off by 20 percent then none are pointing you to a particular trouble. The ones that are off by a much greater percent are telling you where to concentrate your trouble shooting. Pick one at a time to work on, and eventually you will fix one and then another.

This is as much video I have got so far from the sets own tuner but is there another area I could look into like maybe the blanking amp judge by what the image looks like since I turned the IF coils one at a time and kept count in or out but if I turn them I start to lose the video so I left them alone. I’m just trying to figure out if another circuit besides the agc could make this image like this. No change in turning the agc little difference when turning the noise gate.

If agc can distort and mess up video shouldn’t it kill audio as well.

The posted pics are still a very strong sign of a IF alignment problem. The picture almost looks negative, much worse than when fed in at the 2nd IF or test point A.

As many will say, you can NOT adjust the IF visually, simply tweaking a coil a bit to see if it improves what you see on the screen will get you no results, as they interact with each other, the entire process must be followed with a rf frequency generator or sweep marker generator anything else will just make is worse, as anyone else can tell you.

Yes the video looks like a negative but the pic I posted back a few pages was done with the subber on pin 2 of v2 but since changing the 22ohm resistors in v1 and v2 I am not able to get that back again not sure why

It was said in a previous post that if the trap at the antenna input was bad it would be impossible to tune anything in so with that said if the trap were good then if it’s turned in either direction it should change what’s on screen already to at least some degree this one does nothing at all and yes I marked exactly where it was before touching it. Is there a way to tell if it’s bad sams says it’s a 15k pot which it is a pot but it only uses 2 connections no center wiper so I guess it varies the 15k itself from under the adjustment knob.

That almost looks like a detector circuit problem.......

Does it get sound? noise that changes with
channel selection?

I think maybe you should contact a Priest and get
an Exorcism for this tv......


.

It does get sound. Detector circuit ? ? There is snow and noise on screen. Are you referring to the video detect area of the detect diode ? I put video in test point b and I noticed there is a slight waving in the video where else could this ac be getting in since the power supply caps are new.

The 3 pictures you posted above look to me like the delay line is open, and you are
just getting the color portion of the picture to the screen. Only in this instance
it looks like there is no color.....

Does the color control, tint, or contrast control have any effect on the picture?
If any what does each control do? Be specific to each, and the effect.
be clear in your description.

Is the detector diode in there correctly, not backwards. Are each coil close
to the correct resistance? Voltages on the Video Amp & Output ok?

Is the sound crisp & clear, full tone no noise mixed in etc.....
Full clear volume?


.

.

So since pulling the tuner and cleaning it I have snow noise on Screen and sound and there is snow noise on other channels strongest on channel 3 and sound is strong and clear no noise in with sound. Detector diode is in correctly and the diode test indicates it’s good at a reading of 283 but don’t know if it may be leaking.it’s said anything under 3 in a germanium diode is good. It has a 1N60 but if I have to change it all I have is a 1n34 don’t know if it’s compatible. I injected video to make sure the amp and output is still good and it is good but there is no color because I turned the drives down along with the master g1. And I had already checked the IF coils and they are .2 or.3 . When the color drives are up the video I’m getting now there is not a lot of contrast but with video injected the controls work. If the color drives are up the other controls seem to put kind of noise on the screen so I turned them down since nothing is setup no purity nothing. Back when I posted the pic and you said I can see some red in there I had got that from pin 2 of v2 with the subber but since I changed the 2 - 22 ohm resistors in v1 and v2 I can’t get that same result the resistors were 26ohm and 28ohm so they needed to go. Well ok there is a problem I tried to get some color but to my surprise the hue and intensity is not working but the contrast has an affect so that works. It does look like I lost the color no matter how I turn the color drives.ok another update all the color controls do work I had the color killer turned down. I checked with injected video color is there.

This is the latest don’t know why it flips.

Video amp
9-172
7- 13
8- 116
6- 14
Video output
7- 250
6- 153
2- 11
1- 11

Is it possible the video detector diode has gotten reversed? (I haven't read thru this whole tome, so this might have already been asked.)

I did have it out and put another in but it was worse and put the original back in making sure it was right

It should be easy to check if X6 is backwards or not via a DVM on diode check at L6 pins 2 -4, as others have said, it;s looking like it is almost.

Unless, ans I'm not sure this is possible, but could the IF be SO out of phase that it causes a negative video?

If the IF is so sensitive then if it were out so bad I would think nothing would find it’s way to the output. As for the diode I know it’s in the correct way but it does check good but what would video look like if it were leaking as they say about these germanium diodes known for leaking. Can the video detect diode be mounted outside the coil housing rather then taking out the coil every time to try different diodes.

there is no reason why you can't unhook the line from pin 4 L6, hook a new 1n60 germanium up to pin 2 with the removed wire on it's anode for a temporary test run.

The diode is in the coil can attached inside can’t get to remove one side. Correction I can try that.