Well I never got the chance to pull those tubes , can’t run it with no vertical.

For something like losing vertical sweep, you will have to set the chassis up in the service position, if you have not done so already.

The makers of the set have anticipated the need for this, and normally left all wires long enough to prop the chassis up behind the set for easy access and still hook everything up, you just need to be sure the CRT is grounded.

Vertical deflection is dependent on 640v boost via 3 points, vertical height, vertical lin, and the output via C5, if this 640v boost has failed, or the parts it feeds have failed, vertical sweep will fail.
But to have boot voltage in the first place, horizontal sweep/ HV has to be working.

Yeah not sure how I’m going to do that being I don’t have the plug harnesses which would have been nice I’ll have to check into things first hopefully there’s something obvious. For no reason the vertical just dropped dead nothing I did except remove the 6cg7 tube for no more then 20 seconds. Well the wires may be long enough.

On k1 the schematic shows what looks like 24meg but on the schematic it looks like a dot next to the 24 so I checked early television museum schematic and it to looks like .24 meg is there a .24 meg resistor or is this a typo error.

clearly 24meg 2w, hooked to 275v, going down to .4v it has to be.
not a typo, scan error.

No telling what could have happened, :(
Gonna have to re-check the whole circuit, including tubes, power resistors, potentiometers, caps, etc..
I see no real reason for vert to fail w/o V10 being in there, but on the other hand, if you hot plugged it in/out, that may be different, no telling. :/

Well this tv has tell tale signs of it having been in humidity and dampness so I think it may have been a momentary loss in one of the vertical pots as I turned the vertical linearity pot and was alittle stuck at first and I still have boost voltage and all the vertical pots check out fine and vary with turning them. That 24 meg measures 30.59meg slightly high.

at 20%, which is what it was most likely what it was made as, 28.8 would be the top, so 30.59meg is just a hair over, prob nothing to worry about.

The other resistors check good except for that 24 meg all I have is a 22 meg that measures 25meg so I may insert it in there with the one lead clipped. So I checked the other couplets and the both measure 115k while it should be up around 150k so I don’t know what’s with that.

or, you can hook this across pins 1-2

588-SM108031006FE Mouser part #

100 meg 2 w resistor.

the 2 in parallel = 23.424458228 meg.
or just leave it, it should be OK for a while. :yes:

While the other 2 couplets are measuring 115k don’t seem to low ? And that 4 volt source with no load should be higher then 4 volts.

again, it's very unlikely that the couplets are a source of trouble, they would have to be well out of 30% before you should even think to start to replace them.

now, they seem to be well on the edge of OK, and would be more of a pain to replace at the moment.

also, which 4 volt source do you mean?

The tuner pin 3

That shows .4 on my scanned copy, and by nature, AGC is going to change based on given input demand signal, so (if working) don't expect to see what it says there on the schematic, the AGC voltage should change reactivity to the strength of the rf coming into the tuner, adjusting it almost scan line by scan line,

You will note that AGC keying has a link to horizontal pulses via C59, & link to video via r58, this is how it monitors video level and times ACG control for the tuner & IF gain, with no video, it has no control reference.

http://www.earlytelevision.org/Deksn...implified.html

way more info on AGC :p

C59 is 470pf I measured 410pf does ceramic caps go down in value? As for the vertical it does have 640v boost.

ceramic capacitors rarely ever go bad, and most in the set are 20% values unless otherwise listed, and it's very had to test in circuit unless you have a tester that was specifically made to test capacitors in circuit with leads that compensate, then a simple DVM will always give bad (deviated ) readings, especially with lower value capacitors because the length and position of the leads themselves used will skew the test results.

Notice the leads on this $1200 pro tester.
https://media.digikey.com/Photos/BK%...os/LCR-600.JPG

And yes, and mentioned before the vertical uses the 640v boost in 3 areas.

Vertical Height pot R17, Vertical linearity pot R18 and it also goes to C5 to R109 / C3.

Any problem here, and you would most likely lose sweep.

If c59 was bad that would upset the video and possibly sound path.

The chances of being bad are very small, the way to be sure would be to use an oscilloscope on pin 3 of V6 to check for the 450v signal.

again I have never had to replace a Disc cap unless they were physically damaged, IE broken / burned, they pretty much never wear out in these sets..

I don’t know how the hv oscillator has anything to do with IF and sound again hv comes up no sound no pic pull the plug then back on and again one hot gets red about had enough. I could have 2 defective caps 0068 and 0039 for the oscillator so if it don’t start then the tube can get red plate. But the IF is definitely another on going problem.

The problem is multifaceted, look at the block diagram page 5, AGC uses pulses from horizontal output to control tuner gain, if horizontal oscillation is not running, or not correct, or AGC itself is not working, then tuner gain will be wrong and you won't be able to tune anything.
Sometimes, when AGC is not working for whatever reason, an external bias can be used ( battery or the like ) to force the tuner into the right range of gain for test purposes.

You don't know at this point if the horizontal oscillator is stable at the right frequency, or the right amplitude, or the right waveshape, all of this matters.

True I don’t know but I do know that recently I tuned the horizontal coil and was able to get a perfect stable -45 from pin 5 of the hot. Now it changed and cannot get it back to -45 so something is not right and maybe it’s defective caps because I found nothing in the circuit whatsoever that was wrong different tubes both oscillator and hot and still so all I have left is the caps in the oscillator circuit. So if it’s not a defective cap what else could this be it’s not a resistor I checked them several times and the horizontal coil 85 ohms.

Not having it in front of me, I really don't know what else to add, other than if the horizontal circuit keeps being unstable, go full shotgun, EVERY resistor, replace with new carbon film 2% 1w, there is 1/2w in there now, but the new type 1w carbon film are about the same size, and much more stable, it does not matter if the old ones stlll test ok, new ones will last another 50+ years, the same goes for the higher power ones, sizes have come down a lot, so if it has a 2w, put in a 3w , replace a 3w with a 4w and so on.

Replace all caps with higher tolerance and voltage ratings, except for ceramic discs, UNLESS they show physical signs of distress, disc caps almost never fail, as mentioned before, other types do, film types are less likely but the do sometimes.

Like resistors, film cap technology has much improved since the set was made, caps can be gotten with much better tolerance and voltage ratings at the same values now.

this all of course is just a suggestion ! :yes:

So the bottom line is if the horizontal oscillator is not right then the agc won’t be right and that can affect both sound and video even though in the beginning I did have sound but was alittle scratchy. All the film caps I put in are rated for 630 volts.

correct, horz is used as ref for AGC.


example

mouser part # for C83
667-ECQ-E6392JF
$0.69
5 %

So would using a 10% make that much difference in the oscillator circuit compared to a 5%.

The lower % part you can get, IE 5% 2% 1% and so on, the more stable it will be and less prone to drift with temperature change and age, and so on, you buy a 100 ohm resistor at 10% rating, expect it to BE within 10% of 100 ohms and stay there, 5% 2% 1% respectively.

when needed, I replace the carbon composite resistors with metal film 1% types.

The schematic shows only the .0039 400v but no % for that cap so how am I to know what was in there. The horizontal.

It normally has it listed on the part, if it has no listing, a general rule of thumb is that it's a 20% part, unless otherwise indicated, and as always in these cases, it always helps stability to put in a higher tolerance part than you remove, because back when it was made it was a cost issue, putting in 10-5% or more parts was costly, but now, those parts are very cheap and effective.

Well now I look closer and the 2- 0068 and 1- 0039 are all 10% and that’s what I put in the print was small.

I read an article about AGC that the agc is for antenna connections but it’s somewhat not needed for a cable or any other video source so I don’t know if the agc is not working will it still knock out the video and sound from another source such as vcr cable line dvd.

It absolutely will take out RF from a VCR or DVD player I've seen it happen on my own sets more than once.

The amp bias is controlled by the AGC circuit. If AGC is defective you can get absolutely no reception like the IF tubes are removed all the way to problems like signal overload and red plating IF tubes.

Ok I’m at it again the search continues for a cause for this horz oscillator agc problem I have yet to find anything obvious resistor or tube or anything else for that matter.

I don’t understand exactly if the 2 couplets or even one was bad if it would effect the horizontal drive because the 2 resistors within the couplet are 94k and 56k in series should be 150k it measures 114 and 115 k but the cap inside shows it should be .002 and my cap checker measures 3 times above the marked rating so I’m not sure at all if this would effect the horizontal drive along with the agc. Correction the 2 resistors do check ok at 165k and 170k so not so high on to the next.

One crazy thing after another this set is unreal it’s cursed. So now whatever was going on with horizontal oscillator it finally died and at the same time the 190 v source is dropping down to 38v and the 6hs8 is red plating. And yet again went over resistors and double checked the new caps I put in and nothing I can find. I hope the new flyback I put in is not defective.

Get an oscilloscope, already

Well, Good. A dead ocs. is better than one that only works partly. Ok, No Scope, Go find
an amplifier, make probes, couple the input of the amp through a cap. to protect it.
Horiz Osc. is 15khz, take your amp and put it on the Horiz Osc. of a tube tv that works, See
if it delivers sound, and does not kill the osc. Then you can see if your tv from hell has
any osc. action at all. You might have to use a coupling cap, and big resistor, 50K?
so as not to load the test circuit with the amp input. Be aware of that...

Also Remove the plate caps from the H. Output tubes and focus on fixing the osc. And
only focus on fixing the osc. Now that I think about it, you should forget about the tuner,
and other stuff, and focus on fixing the Osc. Use Voltage checks, on the Osc. tube & the
AFC. tube. Use the amp to see if you can hear the osc. Test the sound against another
tube tv, if it sounds faster, or slower, etc.

When the osc. is dead, what happens to the -45V on G1's of the H. Output tube?

Also with this tv working some time, and not others, working in the cabinet, and then not
have you thought there might be some intermittent bad connection? Have you tried
whapping the chassis really good a bunch while it's on to see if symptoms change??

I mean whapping it like Onslow from Keeping Up Appearances......
Anything less is not considered a whap.....


.

A scope would help but it will tell you a tube is bad or resistor or flyback or capacitor or horizontal coil all of which i ruled out except the new flyback I put in. The ohms on the original flyback is different then the new one I won’t say drastic but different.