Sony TV-700U getting audio but no video
 

I have an adapter running from the EXT ANT port to my Magnavox Odyssey 2. Changing to channel 3 and turning on the Odyssey gives me sound but no video. I can hear the Odyssey beeping from the TV and can hear the game playing but all I get from the video is static. The static pattern changes when I turn on the system but it does not looking like the game. Also, the Odyssey works fine on other TVs. Any ideas? :tears:

Have you tried tuning to channel 2 or 4 to see if maybe the fine tuning is far off?

Gave that a shot and I got some video but it went away after a little bit. What does that mean?

Describe it more - did the screen go black, did the picture disappear suddenly or gradually. Did it look normal or strange in some way? Did you try the fine tuning?

It kind of works on another channel. I've tried adjusting the knobs on the rear and side and have been able to put together a much nicer picture, but it's still pretty warped and wobbly. The rear has "H. Freq", "V.Lin", and "Height". I'm not sure what any of these mean though. I know that H. Freq means Horizontal Frequency but I'm lost what V. Lin means and what Height does (changes the height?). The side has vertical and horizontal. I'm assuming they just change the location of the image on the screen, but they seem to change something on the image. It would be nice if I knew what all these knobs meant so I could get the image right.

The side controls are the customer controls. If the set is working properly, they are all that are needed to lock in the picture from rolling up or down (Vertical Hold) and the H is similar for horizontal except that the effect will be that the picture tears into diagonal stripes if it is misadjusted.

Adjusting the controls on the back should only be necessary if the set needs some servicing.

Height does just what you think - shrinks or expands the height of the picture.
Vertical linearity adjusts the picture so top and bottom have the same amount of stretch or shrink. If misadjusted, the picture will look a bit like a fun house mirror.
It is OK to play with these vertical controls to see the effect, as it will be easy to reset them.

I'm not familiar with this set, so don't know why there's a Horizontal Frequency control accessible, but essentially it should set the center point for the H contol on the side. This one could cause you more trouble if you play with it and get lost from the correct setting.
It probably should not be touched unless the side H control cannot make the picture lock horizontally. If that's the case, center the side H control, then adjust Horizontal Frequency for lock. Take careful note of how much you turn it so you can go back if your adjustment doesn't work. It will probably be touchy and have a strong effect, such that good adjustment will occur over only a small range of rotation. Double check that the side H control locks the picture when centered and unlocks it about equally bad when full CW or CCW.

I have one TV-700U working.

Besides that tv-nut said, I can add in practice, fortunately this set are not overly fussy about the V and H user controls (in the side), but anyway, for game console having a little different freq. for H, V or both, a simple readjustment makes the day.

But, maybe it have some sound or video IF misaligment; perhaps marginal to other sources, but maybe being far off for the Magnavbox. If is impossible to find a usable point using the fine tuning, perhaps this are ocurring.

BTW: my set needed a "full cap service", ie, all electros are bad. This can even influence the sync separator, since electro are involved for biasing and coupling. This makes the set fussy about the sync.

In my to-do list is some realigment for my TV-700U; the sound is a little off.

One caution. The service adjustments ( h-freq, V-lin, V-size ) are
very small & delicate. They also have lock tight on them often.
SO go very easy on them !
Sounds like the electrolytic caps are bad in both the Hoz & Vert.
It could also be just a dirty tuner.
BTW the fine tune is multy turn. Could be that is way off.
When you see the pix try turning it 1-2 turns CW & see what happens.
Sometimes you also need to push it in too to engage the gears.

73 Zeno:smoke:
LFOD !

May have made the mistake of fiddling with the knobs too much to begin with so I'm kind of starting with a clean slate. The Horizontal and Vertical knobs both mess with the wobbliness of the screen (the alignment?). I can get the screen almost centered then it just goes out of wack. I turned both of the knobs so that they're at the center location because that seems like roughly where the center point is. I go to adjust the horizontal frequency and I can almost get it just right but not quite.
The best I can get is the screen being slanted. I've adjusted it multiple times and the slant is always in the same direction too.

Here's a video of my fiddling with stuff so you guys can see what I'm talking about. I don't know if it's all a problem with the TV or some stuff needs to be replaced. The knobs are unbelievably sensitive to touch. Sometimes just removing the screwdriver that I am using to turn them is enough to make the image more messed up.

https://www.youtube.com/watch?v=0924Aq3syXc

Your horizontal and vertical are working just fine. However, the image with the edges affected like that would indicate that the fine tuning is way off, to the point that you may be on the wrong channel. It could also be that there is a problem with IF (intermediate frequency section) alignment, but that is MUCH less likely.

If your source is supposed to be channel 3, go to channel 3 on the receiver and then try turning the fine tuning as far as it will go one way and then the other to see if you can find a good picture that locks in solidly.

I tested all the other channels and the current one worked the best still. I think I am going to reapply deoxit cuz I may have not done a good job the first time. I may also try using a different device for the input just for diagnostics' sake. Any other ideas? What's the "intermediate frequency section"?

How could you tell it needed new caps? Were they just visibly bad?

On the best channel, does the picture change when you adjust the fine tuning control? If not, the control is possibly not engaging. :scratch2:

jr

If by "fine tuning" you mean the Horizontal Frequency knob then yes, it is engaging. You can see it working in the video.

No, I mean the fine tuning knob...the outer ring around the channel selector knob. Push to engage.

jr

There's a knob on the left that goes from 14-83.... Is that what you mean? When I turn it it doesn't seem to do much.
However, it looks like when I bump the main channel selector it changes the screen quite a bit. I think I'm gonna clean that knob and see what happens.

No, that’s the UHF channel selector. Perhaps the fine tuning knob is missing?

jr

Ah, the fine tuning knob was a second knob that went around the channel selector. Used it, made a big difference. I was still getting a handful of vertical lines that were dimmer than the rest of the screen and couldn't get the screen to not be tilted right but I'm guessing that can go away with just more fiddling?

I can post another picture or video if it would help. Obviously it won't look amazing but it might help.

Yes, please post a current video.
jr

Ditto: please post another video.

But before you do, did you set the channel selector to channel 3 and then adjust the fine tuning? Most games, VCRs, etc. output to channel 3. They may have a switch to select channel 3 or 4, but most commonly they are used on channel 3.

Here's the vid. Should be on channel three. I am now in the process of cleaning the channel selector pot.

https://www.youtube.com/watch?v=8aVixtKT1cQ

EDIT
I cleaned the channel selector and fine tuning pots and it seems to be much smoother but still am not getting it just right yet.

I guess my next question would be how do I know if the fine tuning is adjusted correctly without the hfreq being in the correct position?

At this point you are wasting de-oxit. If there is something left needing cleaning, it's internal, not reachable from the knobs outside,

It's hard to see in your video because it's overexposed, but it appears you did not find any good fine tuning spot. When the tuning is correct, the diagonal stripes should change to dark diagonal bars (sync and blanking pulses) about 1/10 the width of the screen, and the horizontal and vertical should then lock in solidly.

The picture you are getting is like a bas-relief of the normal signal, showing only the edges of the sync pulses and not nice solid black pulses, and the sync circuits can't lock to that. This normally happens when the fine tuning is way off or the TV and game system are not set to the same channel, but there could be some other cause, I guess.

Can you post a video of how your game system is connected to the TV, in case there is a problem there? Show: where the cable is connected to the game and where the cable is connected to the TV, and any adapter between the cable and the TV.

Here are some images, all with good fine tuning, for reference. I was not able to find an image of bad fine tuning, but it is essentially what you are seeing. All three pics show a standard "Indian Head" test pattern.

Normal picture with test pattern
https://live.staticflickr.com/65535/...4b217ea0_o.jpg

Picture with normal fine tuning, but sync is floating. (You have floating sync, but it's probably due to the poor tuning, not due to a sync circuit failure.) Note the dark horizontal and vertical sync bars.
https://live.staticflickr.com/65535/...e4909f05_o.jpg

Picture with normal fine tuning but horizontal hold (H) control or horizontal frequency control is misadjusted
https://live.staticflickr.com/65535/...9690ce41_o.jpg

Okay here's the third update. This ones a bit longer cuz I went through and did all your requests. There is a bit of talking too. Feel free to put it at 2x speed.

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

Due to age, some capacitors simply leaks, or lose value. Is common with electrolytics. Since this small TV uses a lot for inumerous functions, various curious symptons can occur.
Even with some "half bad" caps, the TV can be adjusted to almost normal operation, but some controls become very picky.
I have one TV-700U working and one spare (with dead CRT). One had ALL electros >5µF bad, and other had 1/3 bad. Statiscally, I bet that at least some can have problems.

If are some bad caps at same time with some RF/IF misaligment, the TV will be very difficult to use.

Are you aware of a full cap kit anywhere or should I just go through and find each one? I wasn't able to find a service manual for it online, or much info about it to begin with.

A kit I believe it don't exists...

I have the SAMS of this model. If you not able to find the schematic, I can take photos of it.

Sounds good. I should probably be able to find everything I need inside. What is SAMS?

At about 5:00 minutes, the "tangent lines" you point to are the edges of what should be the solid dark bars. Although this is the best fine tuning you have obtained ar this point, it still looks like you are far off the proper tuning point. This effect of seeing edges only means that you are getting only the higher video frequencies (which make edges) and not the whole signal (which would inlcude lower frequencies as well that make solid areas).

The blurry vertical black bars you see earlier in the video are from being very far mistuned, such that you are picking up almost none of the signal and instead are seeing effects of the TV interfering with itself somewhat. (The very high currents in the horizontal sweep can produce a weak interference signal that is invisible compared to a good, properly tuned-in signal from your game.)

"Bas relief" is pronounced "bah relief" and means a shallow carving in stone.
https://www.britannica.com/art/bas-relief

Your sync is not totally floating - the image jumping around or tearing the way it is indicates that the sync circuits are trying to work but are not getting a solid signal to work with.

Turning the H frequency and H hold should find a condition where the diagonals go more or less straight up and down (but still jumping around) and then go diagonal the other way as you adjust further. You had this condition in the earlier videos.

At 8:49 you turn the horizontal frequency and you do get this condition. :thmbsp: This is an indication that the H adjustments are good, but again, the sync circuits can't work properly without a solid signal.

Around 9:00- 9:30 you can see a hint of the solid dark sync bar on the left but the main effect is the white "bas relief" edges.

There is still a possibility that the tuner or IF (intermediate frequency) amplifier section is bad in some way worse than just fine tuning. It would be hard to diagnose without opening the set and having the right test gear.

I don't know what the mechanical details of the fine tuning are on this set. I would expect a range of multiple turns with a stop at each end, but the stop could easily be broken. In that case it is possible that the tuning element would fall out of its place fi you tuned too far, but that hasn't happened because you are still getting a tuning action.

Have you been able to go beyond the current best fine tuning point and see if it continues to get better or gets worse again?

SAMS, people from USA can explain in detail, but for short, was a North American service specialized in making own drawing schematics (generally clearer than from some brands), and, amongst other things, making a local replacement/equivalent list.

In other words. I have it's schematics and parts list.

Any chance you could send them over?

Also man, taking apart this thing is a nightmare, there's so many wires everywhere. You guys make this stuff sound easy!

Am I cooked? I think I broke what looks to be a resistor. It's hard for me to tell because I've not worked on hardware this old. Will I need to replace this piece or will it still work without the outside blue part?

Link is to a Drive folder with pics.

https://drive.google.com/drive/folde...Rz?usp=sharing

This is a coil***. It seems to have damage only on it's externals. Is easy to test if it is ok. You can measure continuity, since it will have some low ohm value.
***is good to check to be sure in the schema, but seems to be one coil and not a thermistor etc.

1) It looks like both your VHF selector & VHF fine tune knobs are missing.
2) try a VCR on it.
3) IIRC the RF input is a 3.5 mm jack. To hook up you need the right adapter (s)
for the coax. That would be F- fitting to 3.5 MONO.
4) That is a coil. Looks like it had glue on it.

This is not an easy set to deal with. Forget about a re-cap until you
work on some more forgiving sets.
Easy for us ? Most of us are former techs or long time hobbyists.
You do learn a bit after being inside tens of thousands of TV's

73 Zeno:smoke:
LFOD !