OK guys. I've been asked to look this chassis over and see if I can find the problem. Well I can't.
The background is that it has been recapped and some of the resistors have been replaced. It did have vertical when first tried but then lost the vertical soon after. The Vertical Centering pot does move the trace up and down. The Vert. Lin. pot has little effect.
Here's what I did so far.
1) I checked out the Vert. Osc. and the Vert. Output transformers. Both ohmed out good.
2) I ohmed out the yoke and it checked good.
3) Checked the tubes in the Vert. section along with the tubes in the Sync section. All tested in the good range.
4) Traced all the components in the Vertical section to see if they went where they were supposed to along with their values. All looked good.
5) Checked and cleaned both the Height and Vert. Lin pots. Both checked good on the ohmmeter.
6) Did a through visual for shorts, solder blobs, etc.
7) Tapped on the chassis some but that didn't help either. :>).
Here's a picture and then a video of the situation.
Any ideas guys?

https://tvrestorerguy.com/wp-content/uploads/100_0184a.jpg

And the YouTube video:

https://youtu.be/RyM6xCjcXiY

What about the hold pot ?

What about the hold pot ?

Yeah, that ohmed out good. It was cleaned too.

Got scope? Checking the waveforms against the schematic (if sams that early have waveforms) should reveal issues.

Another method is to connect the heater to the output tube grid...That will inject a 60Hz signal and give the output some drive. If the output works with injected drive then you can also do the same at the osc. grid to check whether the isue is in the coupling between osc and output or a lack of oscillation.

Better to couple it through a cap. Value not critical, .047 - .1 mf or so.

Guys,
I coupled the grid of the output tube to the heater and then did the same for the OSC. tube. I used a .047 cap as suggested.

The first picture shows without any heater coupling to the grid.
The second picture shows the Output tube.
The third picture shows the OSC. tube.

https://tvrestorerguy.com/wp-content/uploads/100_0189a.jpg
https://tvrestorerguy.com/wp-content/uploads/100_0188a.jpg
https://tvrestorerguy.com/wp-content/uploads/100_0187a.jpg

Looks like when the heater is coupled to the grid of the OSC. tube I get the most Vertical.
I'm puzzled. I thought it would be greater vertical with the Output tube coupled.

I'm not electronically adept, but just wanted to chime in that when I acquired my restored 630 I had a heck of time getting the rear adjustments just right. It took a careful tweaking of all controls to keep the picture centered and steady. The "sync lock" thumbwheel control was particularly touchy. Once set it's been fine.

I'm not electronically adept, but just wanted to chime in that when I acquired my restored 630 I had a heck of time getting the rear adjustments just right. It took a careful tweaking of all controls to keep the picture centered and steady. The "sync lock" thumbwheel control was particularly touchy. Once set it's been fine.

Joe,
Where is the "sync lock" thunbwheel" control?

Joe,
Where is the "sync lock" thunbwheel" control?
It's on the rear chassis with the other controls. It's the small thumbwheel control that is positioned slightly higher than the rest of the controls. I believe towards the middle, right above the antenna input panel.

Where is this sync-lock control in the circuitry?

If I'm not mistaken that sync control is an aluminum square can with the adjusting screw in the center. I don't think it's on top it's on the under side of the chassis .

If I'm not mistaken that sync control is an aluminum square can with the adjusting screw in the center. I don't think it's on top it's on the under side of the chassis .

Yes... horizontal frequency slug B2, and the terminal strip below is "sync link"

jr

Vertical oscillator blocking transformer?

The control I was mentioning is on the back of the chassis directly above the antenna terminals. It's a thin control shaft with a thumb-wheel end. Here's a pic from the Net where you can easily see it:

The control I was mentioning is on the back of the chassis directly above the antenna terminals. It's a thin control shaft with a thumb-wheel end. Here's a pic from the Net where you can easily see it:

Sorry, the antenna terminals are in the upper left, above the power transformer, the terminal strip by the ul sticker is the "sync link" strip, see my previous post.

jr

Sorry, the antenna terminals are in the upper left, above the power transformer, the terminal strip by the ul sticker is the "sync link" strip, see my previous post.

jr
My bad- I don't have easy access to the back of my set. No, not the antenna terminal. It's above what looks like an antenna terminal near the center of the back the chassis.

Vertical oscillator blocking transformer?

Well maybe. It did ohm out good. I have another NIB that I thought I'd try to see what happens.

Primary to secondary leakage in the blocking trans could cause bias issues...Shorted turns could detune the frequency and suppress oscillation. Did you compare tube/schematic voltages in the vert stage yet?

Blocking xfmr was my first thought, once he got sweep by injecting at the osc. grid.

It was the blocking transformer! I had another one here and put it in. Bingo!
Thanks for all the suggestions.

:banana::banana:

:thmbsp:

Can you measure anything odd on the bad transformer? Seems as if we have seen several now that have appeared to be good, but did not function. :scratch2:

jr

:thmbsp:

Can you measure anything odd on the bad transformer? Seems as if we have seen several now that have appeared to be good, but did not function. :scratch2:

jr

I measured the leads each other and to the case. Everything seemed good. I then hit it with my heat gun and got this:

https://tvrestorerguy.com/wp-content/uploads/100_0196a.jpg
https://tvrestorerguy.com/wp-content/uploads/100_0197a.jpg

Yup, a transformer! I ohmed out the windings again and the values crept up from pri-1130 to 1533, sec-153 to 173. I also checked for shorts between the leads and shorts to the core. All seemed good.

Wondering if a shorted turn could kill AC operation, but change DC ohms only a tiny amount, so undetectable with an ohmmeter?

That's what I'm thinking. Or there is some leakage that won't be measurable with a low voltage ohmmeter. You'd need an insulation tester - AKA "megger"

Well now after getting a decent picture with direct video injection, I can't get a good picture through the antenna terminals.
So I replaced the resistors in the IF stages. The caps were previously replaced. Still not a good picture. I get decent sound though.
So I tried a quick alignment but the signal was very small going through to my VTVM. When I made an adjustment the needle moved just a little bit.
After that I tried it again. No joy. Here is the picture I get of a test pattern. You can see it is there, it just isn't very good. The tubes were tested and they are good.
Any ideas? Thanks.

https://tvrestorerguy.com/wp-content/uploads/100_0246a.jpg

Looks like some sort of regeneration (?)
Is this what it looked like before you attempted alignment?
It helps others to help you if you show a picture of the problem before you try to fix it.

Are all tube shields in place?
Could it be an AGC problem?
Sorry for a dumb question, but did you completely disconnect everything you used for direct video injection?

Looks like some sort of regeneration (?)
Is this what it looked like before you attempted alignment?
It helps others to help you if you show a picture of the problem before you try to fix it.

Are all tube shields in place?
Could it be an AGC problem?
Sorry for a dumb question, but did you completely disconnect everything you used for direct video injection?

Yeah, the same thing before the alignment.
All shields in place.
Everything is disconnected.
Actually the same thing before I replaced all the resistors too!

Warning: I would wait for more comments and ideas from others who have worked on this chassis, but here's my 2 cents anyway.

I forgot there is no AGC, just manual Picture control - I would check the voltages and operation of the control.

Also maybe a bad bypass cap in the IF (all those 1500 pF caps).

Good operation with direct video injection rules out anything after the injection point.

The 1946-48 630 chassis have a reputation for bad mica caps in the IF...One of the only cases where I advocate recapping the micas.

The 1946-48 630 chassis have a reputation for bad mica caps in the IF...One of the only cases where I advocate recapping the micas.

Yes, I replaced those micas and the one coming from the tuner.

Might be a good attack to take a spare 1500 pf and bridge the replaced ones one at a time. (?)

Might be a good attack to take a spare 1500 pf and bridge the replaced ones one at a time. (?)

The micas in the IF stages are all 270pf. Are you saying to bridge each one with a 1500pf one?

Sorry, I meant the 1500 pf bypass caps that are everywhere. Did you replace any of them? If not, that is even more reason to look for trouble with one of them.

Sorry, I meant the 1500 pf bypass caps that are everywhere. Did you replace any of them? If not, that is even more reason to look for trouble with one of them.

OK, that makes sense. None of those were changed. There's a bunch of them. I'll let you what I find.
Thanks.

OK, I jumpered each 1500pf bypass cap with some clip leads attached to a 1500pf mica cap. It wasn't as hard as I thought it would be. Still no joy. I'm suspecting the tuner.
Anymore ideas I could try?

Even though the IF tubes test ok, I would try swapping them out to see if the symptoms change. :scratch2:

jr

Even though the IF tubes test ok, I would try swapping them out to see if the symptoms change. :scratch2:

jr

:thmbsp:

I take it you found no hot spots that changed the behavior when touched.

How does the picture react as you turn the Picture control up and down? Do the streaks move? Or is there only a contrast change?

Another question: what do you get if you disconnect the input signal? Can you get snow without streaking?

Even though the IF tubes test ok, I would try swapping them out to see if the symptoms change. :scratch2:

jr

OK, I swapped out each one, one at a time with another NIB RCA 6AG5 that tested like new. Still no joy. Basically the same with each swap out. Good idea though.

Another question: what do you get if you disconnect the input signal? Can you get snow without streaking?

When I disconnect the mica capacitor going to the 1st stage IF, the streaking goes away, but I also don't just get snow. I get some lines that I go away with the H. adjustment on the back. But never get any snow. When hooked back up, the streaking is there with the picture.

I think he meant test pattern gen to tuner not tuner to IF...

If you have a B&K analyst or another set that uses the same IF freq, you could inject a signal into the IF and check it's function.

I think he meant test pattern gen to tuner not tuner to IF...

If you have a B&K analyst or another set that uses the same IF freq, you could inject a signal into the IF and check it's function.

OK. I'm uploading a video of what I have and what happens. It'll be ready shortly. I appreciate everyone's help.

That was quick!

https://youtu.be/RG8w20No1Ew

I didn't understand what it was you disconnected in that video. I did intend for you to disconnect the antenna input, not the IF.

Anyway, I think the next thing I would try (after disconnecting and reconnecting the antenna) is removing/swapping the RF amplifier (V1).

I didn't understand what it was you disconnected in that video. I did intend for you to disconnect the antenna input, not the IF.

Anyway, I think the next thing I would try (after disconnecting and reconnecting the antenna) is removing/swapping the RF amplifier (V1).

Yeah, I disconnected the ant lead to the 75/300 ohm adapter.
I swapped all 3 tubes in the tuner (6J6) with a good one from stock. Still no joy. I also subbed out the 6AU6 DC Restorer tube and that didn't help either.

If the mica caps have been changed in the IF strip, the IF strip most certainly requires a proper sweep alignment. It looks like the alignment is truly and well out.

Proper alignment is not too huge a task. It just require a bit of knowledge, some patience and the pro power equipment. I learned to sweep align a TV if strip as a teenager more than 50 years ago and the knowledge once gained will remain useful.

I have a BK 1077B and injected video on the grid of the Video amp. Worked well. Then used the IF mode to inject a signal from each of the 4 IF stages. Same problem.
I'm suspecting the Video Detector circuits. It is a 6AL5. Is there anyway to use the 1077B to check this section out? The manual and Kiver's book seem to skip over this section of circuitry. BTW I substituted the tube with a another one that checked good. No joy.

You should be able to inject your IF signal directly into pin 1 of the PIX 2nd detector and see something if it's strong enough to drive that point.

When injecting into the grid of each IF stage, did you pull the preceding stages' IF tubes (to make sure they are not driving some garbage in with your injected signal)?

Edit: have you checked for open coils in the detector circuit?

Silly me, but it sounds like the sound is good and clear..... Not the IF ???

Looks like the streaking may be the set trying to sync off any dark spot
in the picture..... You will recognize this if you ever played with over the
air scrambled pay tv.....

What's going on around the video detector circuit....

Not sure where all that stuff gets picked off on a 630.....

Good long video by the way... Hard to get anything off the ones
people post that are only 20 - 30 seconds long.....


.

I found the problem. It was one of the Peaking coils from the Dectector stage.

Item # L188 in the RCA manual and #L119 in Sams 54-18. This Peaking coil came form the junction of another Peaking coil from the plate (pin 7) of the 6AL5 Dector and the Coupling cap #c138 (.05uf) RCA, and C50 in the Sams manual. From the junction is the bad Peaking coil, then it goes to a 3900 ohm resistor to ground.

I couldn't not fix it. I had one end, but could not locate the other. I looked up the properties (8 ohms and 250muh) and looked up a similar coil in a spare parts Motorola chassis that I have. Sure enough there was one that was 7.2 ohms and it was a "Yellow Dot" coil. I found it and clipped it out and soldered it in. Bingo!

The picture isn't all that good but it does confirm the bad coil was the problem.

Thank to all you offered help. old -tv-nut got to thinking I need to recheck those coils. That was the key.
I'm locating a replacement coil from a parts chassis that my buddy has so when I get that soldered in. I'll do a quick alignment, and declare this off my bench.

I could have sworn I checked all those coils before! Sigh......

https://tvrestorerguy.com/wp-content/uploads/100_0264a.jpg
https://tvrestorerguy.com/wp-content/uploads/100_0265a.jpg

hooray!

The coils in the detector circuit are not for peaking, but for suppressing the IF frequencies and harmonics. They must have continuity to pass the detected video to the first video amp. I think what you see with the coil open is a weird DC clamping effect involving the first video amp grid.

Oops - I read it wrong - L188 is a peaking coil.

hooray!

The coils in the detector circuit are not for peaking, but for suppressing the IF frequencies and harmonics. They must have continuity to pass the detected video to the first video amp. I think what you see with the coil open is a weird DC clamping effect involving the first video amp grid.

Being pretty new to this I have heard about peaking coils going bad and I was wondering what is usually the cause of failure? Is it always a open coil or does the resistor ever go open or change value. And what causes them to go open -excessive current -physical damage?

The resistor in parallel (if the peaking coil has one) affects the bandwidth of the peak (or null, if it is used in a trap circuit). The DC resistance of the coil is usually much lower than the parallel resistor, so the resistor value could change a lot and you might not notice the effect. Coil failure hypothetically can be either opening, or shorting of one turn to another.

I think that these low power peaking coils usually fail open due to corrosion over a long period. Coils and transformers that carry high power (like in the deflection circuits) can fail due to heat or arcs causing shorted windings. In this case, the AC operation is ruined, but the DC resistance may not change much, because only one turn is shorted out of tens or hundreds.

Maybe some others can chime in on which types of failures typically occur in different coil applications.