Here is a plot of 1 up to 250 seconds. Is that what you mean?

Hi All;
I would like to see a circuit diagram ?? So, I can build one as well ..
THANK YOU Marty

And the SW for the Arduino...

Does anyone know if the black cardboard tubes you have used are available anywhere new or even new old stock?

I used to see them in the mfgr.'s catalog and in the radio supply stores but
no more. Seems like these would be a good sale item for restorers.

Cliff

Caps are cheap, why trust a nice old set to 50, 60 yr old caps that MIGHT have reformed, or maybe are just "Playin' Possum", as it were ?!?

I'll see if I can figure out how to draw a schematic using the free Eagle CAD program. I will need to clean up my rather messy code, but I will post it. I will make a new thread when I post them.

Hi All;
Sandy G., Maybe to you caps are cheap.. But, for me they are a major outlay.. It will take me a long time to come up with the funds for just the electrolytics, to say nothing about the paper caps.. Yea, I know, I just got the 630TS, which means I am going to have to sell alot of Stuff to make up for it..
THANK YOU Marty

[QUOTE=DaveWM;3058394]Also if you reran the test on the old caps does the graph change (reformed) so the low current target at rated voltage is reach sooner.
QUOTE]

I ran the reform process again on the two old RCA caps and attached are the plots. Yes, they got a better result from a second reforming. They both still show a lot of dielectric absorption, as seen by the LC75.

The cost of capacitors will be a lot lower than the cost to construct this Arduino cap reformer. Although I may be able to save a few old electrolytic caps, most will still probably need to be replaced in my 630TS.

Hi All;
I asked about the reformer circuit for a couple of reasons.. 1. for all those beside me who would want to build one.. 2. I am cursious about what all is in it, maybe I have something else that is lying around that would work.. 3. Maybe someday I won't be a broke as I am now..
THANK YOU Marty

Yeah, the cost of the new caps would be INFINITESSIMAL compared to trying to find a 10BP4...or some other virtually Unobtainium component that gets destroyed because of a cap failure..

Hi All;
Yes, that is why I am in wait mode, and Not plugging in anything.. I couldn't afford replacing many of the items that would be vital.. But, I can do other things, like check tubes, check resistors, and the like.. Making a list of what is needed.. These are no cost things, that I can do in the meantime..
THANK YOU Marty

Yeah, man, I wasn't makin' fun of you or anything like that...Shit, Money's pretty damn TIGHT around HERE, too.. First thing, first, last & ALWAYS is SAFETY... NEVER get yrself hurt..Second is to always BE CAREFUL & make sure you're doing things right, 'cause you DON'T wanna "Woof" some expensive parts...Or even some cheap ones, for that matter..Thirdly, but maybe most importantly, in a way, is to try to PRESERVE these wonderful old devices, so FUTURE generations may marvel on them as WE do..Just think of the JOY some guy in the year 2150 or so will have owning an OPERATING 200-year old TV...Shit, they MAY pull out the 150 yr old Honda generator from the back of the cave & worship the snow on the raster...

Well, the cap was indeed original....all of the wax caps have now been replaced with new mylar jobs. Since the set was working prior to this, I decided to plug it in at this point, and check my work. Everything's up to snuff, and the picture is much crisper than it was.....now for the last leg, the electrolytics.

The issue that brought about earlyfilm's post was my set losing horizontal lock when I change the channel, and having to power down the set for a period of time to get it to lock back in. The picture locks in fine as long as the set is left on the channel that it's set at when I power the set on.

Now I probably shouldn't have done this, but I did it anyway.....without a scope available, I applied the "golden screwdriver" technique, and tweaked B6 all over the place, using the rest of the controls to try to tune everything in......

Well, it worked, kind of. Whereas before I had to power down the set for an hour or longer to get the horizontal to come back, now I just have to flick it on and off, and it pops back into alignment. If I made any improvement, it was by dumb luck more than anything else. Picture size, linearity, etc, all seem close to dead on.

At the moment, the horizontal hold is at the end of its range clockwise....I can now bring it counterclockwise almost 1/2 turn without affecting the picture, and before I had to leave it buried to the right for the picture to lock in.

In the setup procedure, it says "If more than 9 bars are present Just before synchronization, turn the horizontal locking range trimmer (B5) slightly clockwise. If less than 7 bars are present, turn B5 slightly counterclockwise. Turn the hold control counterclockwise and momentarily interrupt the signal and check the number of bars present at the pull-in point. Repeat this procedure until 7 to 9 bars are present."

I never got down that low, there were about a dozen bars at best, maybe 20+ at worst. The horizontal locking range control seemed to have almost no effect on anything.

Something is telling me that I'm dealing with a resistor out of tolerance rather than a setup procedure, but I could be WAY off in that assumption. Thoughts?

[QUOTE=Zenith6S321;3058457]I see from your graph that full rated voltage is applied after only a minute or so. I believe this is too fast. I generally reform much more slowly and I use a limit the initial current to no more than 3mA. I will then leave the capacitor and return, say 15 minutes later, up the current again to 3mA step-by-step until the rated voltage is reached and the current reduces below 0.1mA.

I have reformed quite a few capacitors with a simple variable DC supply. (I first used an old variac, rectifiers and series resitance but now use my Sprague T06 capacitor checker).

I assume by diectric absorption you are referring to leakage? Certainly the older capacitors leak more than newer capacitors. But that was normal. What is important is the leakage is kept under control and that it remains low. I find gently reforming and lengthened testing results in a higher percentage of saved capacitors.

The leakage current scale on the graph is too high which does not allow you to see the resultant leakage current accurately. You must be able to ascertain that the leakage is below 0.2mA inn order to determine whether the capacitor is good or bad.

The resistance indication on the graph is interesting. Perhaps the fluctuation is the dielectric rebuilding process?

If you have the original RCA notes or the Rider notes, you can find how to adjust the horizontal blocking oscillator transformer without a scope.

The RCA Synchroguide oscillator circuit used by RCA and others for over a decade is quite straightforward to adjust. It comprised of the oscillator tuning adjustment and a separate sine wave stabilization coil. In the earlier sets, these were mounted on the same coil form.

In this set you are first told to short out the stabilzation coil (I believe terminals C and D) and adjust (under the chassis) to frequency. Because it is a blocking oscillator it behaves similarly to the vertical blocking oscillator in the way it locks. The best lock position for the horizontal oscillator is to sync at just the point where the sync bar just disappears to the left with this adjustment.

After adjusting the oscillator, remove the short from C and D. Turn the horizontal hold to the far left, interrupt the signal and you should find the picture out of sync. Adjust the sine coil (from outside of chassis) so that about five to seven bars are seen before it pulls into lock. The adjustments interact so that you may have to go over it a few times.

You can tell if the sine coil is misadjusted: if the sine coil is adjusted to far one way you will get double triggering and you will hear a "chipping" sound when you adjust the horizontal hold. Too far the other way and the noise immunity is lost: verticals in the picture will look coggly on weaker or noisy signals.

I do not think there is likely a resistor problem. You need to ensure the oscillator and sine wave coil are set up correctly first. I would simply leave the locking range trimmer at about 1 1/2 turn from fully clockwise and see to the oscillator first. These adjustments all interact.

Try and find the RCA notes as they are pretty clear on how to do this. Also my memory is not as good as the written notes!

I searched the internet for capacitor reforming current limits and found a wide range of values. The highest value I saw was from my Sencore LC75 manual that describes your supply setup and says to limit the current to 50 mA! I thought that value was way too high so I used 5 mA. To make it visible on the graph I multiplied the current value by 100, so 500 for the current on the graph is actually 5 mA (sorry for that confusion factor). I will try using your 3 mA value on the next caps I reform.

Until I bought and started using the LC75 I had not heard of dielectric absorption. Here is a good description that echoes what is said in the Sencore manual:
http://en.wikipedia.org/wiki/Dielectric_absorption
It goes on to say that all capacitors have some amount of this and its generally not a problem for capacitors used in power supply circuits.

I was not able to find a way to show multiple scales on the graph to make it more readable. I started out using a value of .2 mA for the target final leakage value. I have since found formulas in the LC75 manual that they got from EIA RS-395. The manual provides a table of acceptable/expected leakage values calculated from those formulas. I ended up using those formulas in my program so that it calculates the target leakage value and terminates the reforming when it is reached. During the reforming process the program prints out, on the Arduino serial monitor, the voltage and current applied to the capacitor. That data is what I cut and paste into a spreadsheet to make the plots. The Arduino analog inputs have a 10 bit (0-1023) resolution so the voltage sensing resolution is 1 volt (0-1023 volts) and the current sensing resolution is .01 mA (0-10.23 mA).

The resistance shown is calculated by taking the sensed voltage and dividing by the sensed current. So it is an equivalent DC resistance due to the leakage current (not ESR). Some of the fluctuantion probably is the rebuilding process, but I suspect a good bit of it is from the limited resolution on control of the pulse width modulation used to drive the two step-up transformers shown on the schematic this thread: http://www.videokarma.org/showthread.php?t=256919
The pulse width has a range of 0 to 255 with a value of 127 producing a 50% duty cycle waveform that I use as the upper driving limit. When the leakage current gets low a single increment in the transformer drive can make a sizeable change in the quadrupled output voltage.

If you ever get down to Buffalo, would you be willing to give me a hand with the adjustments? I'm sure you could claim some of the television booty in my basement to make it well worth your while ;)

In any event, I watched Lawrence Welk on the set last night, and for the hour that the program was on, the set was perfectly stable with a bright picture.....probably because I didn't change the channel ;)

I accidentally replaced a couple 1 kV caps with 630V caps, so I have to go back in there and do that so I'll be able to use it safely. It's shelved for the time being, figured I'd do the cap replacement at the same time as the alignment.

A lazy Sunday, so I decided to go in and replace those caps.

After that was done, I started to reassemble the set, and noticed a control that I'd missed before, because it was half-covered with a sticker.

"HORIZONTAL LINEARITY". Well son of a gun!

Powered up the set, and went to adjust it when I realized that the adjusting screw that would be IN the pot, is missing! :eek:

I have absolutely no idea how it's locking in at ALL, given that. The pot itself is slightly askew, so I'm gonna be posting in the classifieds for a horizontal linearity control, unless someone happens to read this post, and has one to spare.

I sit here scratching my head as to how it's even working, and how I missed this before!

Hi All;
Could you please give the rest of us the Value of the Horizontal Lin Pot.. Maybe, we can all go and look thru our extra spare parts or junk drawer.. (under the fridge) And see whether we have anything that will work..
THANK YOU Marty

Another interesting thing has cropped up as well. Watched the set for a bit, and I noticed that after about 15 minutes, the horizontal sweep shrunk about 1/2" on each side. The picture itself didn't seem to compress, the sweep just shrunk. It didn't shrink beyond that, but the picture did seem to dim somewhat. I can bring the picture back to the edges with the AGC, but then it goes out of focus. If I tune the set to a blank channel, it gives a full raster.....

The 6BG6 was very slightly gassy, and now it seems to be more so. Didn't check the tube yet, but I have a spare that I'm going to plunk in to see if that changes anything....

Kamakiri,

Lets determine what happened. The Horizontal Linearity in this set is a coil and not a pot. I assume that your typing got a little ahead of your thinking.


On the apparently missing slug in horizontal linearity coil, find another slug from a junk chassis about the diameter as the hole in the present coil and try it. It probably won't be correct, but it will be a lot closer than no slug. After finding a slug and adjusting it for more or less correct horizontal linearity, repeat the horizontal alignment instructions in the sequence that RCA and Sams gives them.

http://www.earlytelevision.org/pdf/R...-Sams-74-8.pdf

Sams page is 18, the PDF page is 21 for the alignment instructions.

Make a paper print of the page and check off each as you do it.

You will notice that Horizontal Linearity adjustment is in the 8th line of those instructions.

Misadjustemnts here could cause the shrinking that you mentioned in your next post, and so could an incorrect horiz drive setting, or a cathode resistor heating.

Consider finding a 1950's or early 60's era scope. They are not expensive. After a simple recapping, they will be as good as new. Be sure to pick one where the schematic and service instructions are available. The newer scopes are more expensive and they are not as rugged when used around tube era voltages. After you have a scope working, see how far you are out on the "peaks" that you assumed were perfect.

James.

Yes, I'd meant to say "coil", thanks for the correction :)

I've got a Hickok scope that would fit the bill, just needing a recap....something that I've been meaning to do.....actually was going to be my next project after this one.

Just so I'm following correctly, a misadjustment in this would potentially cause cathode resistor heating......is it likely that the resistors that were weak to begin with? I'm assuming the heating would cause failure, if the set were operated long enough, and the heating is being caused by an overload.

You'll need a little patience with me at this stage, as I'm trying to understand what is happening, electrically.

Arrrrgghh! No. I was talking about sweep shrinkage that could be caused by misadjustment. This would be the result of the problem and not the cause.


I was also typing without thinking and changed subject in mid-sentence.



My one sentence expanded and written as three sentences:

Misadjustments in the syncro-guide circuit (page 18 above) could cause the sweep shrinking that you mentioned in your next post.

Other causes for this shrinking might be an incorrect horiz drive setting (the trim-cap), or a cathode resistor heating or one of the low voltage electrolytics in the horiz sweep. In short, anything in the horizontal sweep and sync circuits that causes a tube to pull too much current or simply a gassy tube can cause sweep shrinkage.

(Reasoning: Normally when a picture blooms, as you described, one assumes that it is a weak 1B3 or an isolating resister in the HV circuit. However, you mentioned that the image seems to be cropping while shrinking. This latter clue may or may not indicate a sync issue, especially the timing and/or pulse width, in the circuit where the horiz sync pulse is feed back to the sync tube, or simply a syncro-guide misadjustment.)
_______________________________________________

On your Hickok scope, make sure you either have the original probes, or the circuit diagrams of the original probes, so you can repair or make new ones, as they are a needed part of the scope. A set of correct probes is needed not only for use, but for the safety of your scope.

My suggestion for now is for you to go ahead and set the TV by eye. After you have repaired your scope, you recheck the sweep and set the peaks and then recheck the whole process. My guess if that you will find it works better after being scoped. These controls do interact and can sometimes confuse an experienced repairman.

For the record: During the era that these sets were in use, one would sometimes find the linearity coil slug or both the slug and brass screw missing!

Horizontal linearity has nothing to do with locking the picture. It is meant to make the picture physically more linear.. That is Not squeezed, stretched, or, oblong. It has nothing to do with the oscilator. That control is an adjustable capacitor. Looks like someone lost the screw. Hope they didn't als lose the sheet mica.
Bill Cahill

Hi All;
I am truely again amazed at the Knowledge and Insight of a number of the People in this forum..
As I have said in many other groups that I belong to, that the Knowledgeable people in the group should write a Paper or Book, so the knowledge can be passed on to those of us who are either too young or who have just gotten into that particular hobby. And so the experience and knowledge will not be lost, atfer they are gone..
It is a real education to save and print out this and many other postings that really get into the meat of a particular problem.. Thank You to those who help in the education of the rest of us..
THANK YOU Marty

I get where you're going here. I was going to ask, then why does the set have a full raster on blank channels, but as I'm understanding this, there wouldn't be, because there is no signal for the syncro-guide circuit to do anything *with*. Since there is a full raster off-channel, I'm not dealing with a deflection or HV issue, that would be the wrong circuit to even think about. Am I on track here?

Being responsible, the first thing I have to do is re-check all of the tubes in that section (might as well re-check them all).

Should I do any further component checks (as in resistors, etc), before I begin eyeballing the setup? The set has about 8 hours run time on it since the re-cap, I just don't want to let any "bugs" it may have do any damage.

Yes! And also why adjusting your AGC shifted this!

Many newbies mistake this for image bloom from high voltage issues and it is kinda hard to locate the trouble when looking in the wrong place.

As you just said, check all your tubes, but remember, the final check on a tube without any shorts is how well it works in the circuit. Actually, I usually check tubes, especially for shorts, before the first power-up, to lessen chances of frying a newly installed part.

This would be a good flow plan to complete the electrical work:

1) Check the 39 & 47 ohm resistors from the cathode of the 6BG6 to the -120v source.

(Not related to the problem at the moment, but also check to see if the fuse in the damper circuit is the correct value. I've seen some of these increased in value by servicemen to prevent callbacks as the sets got older.)

2) Find a slug that fits the horizontal linearity coil and then adjust the horizontal linearity. (Sams # L42 and Adjustment B4) Use your DVD alignment pattern for this. If your linearity does not change, your coil may be shorted, or there may be a wiring error from recapping. The set should be in its working position (not on the side) when making the final linearity adjustment.

If you think the used core you are testing makes too much change, try a smaller core.

3) At this point get yourself a red grease pencil and mark the Sams "B" numbers on the correct parts, so you won't accidentally align the wrong part. (Don't ask me how I know this is important. :dammit: )

4) If the image looks reasonably OK and only a minimum of overscan, follow the Sams page 7 for setting the AGC Threshold, but do it visually for cleanest picture (ie, back off to just before overload) for now.

5) Follow the Sams page 18 synchro-guide instructions in order, except for checking the waveform. Since you have no scope, yet, you will judge the correct position of B6 by the most stable lock-in range.

6) After finishing step 5, set the set aside for now. If it is behaving better, it is OK to temporarily slide it in the cabinet watch it, since a little running time might help to drive out any remaining moisture.

7) When you get the scope working and you have either built a low capacity probe or confirmed that yours is not leaking, check the B6 adjustment again and if it is out, correct, and let us know what you found.

After correcting the wave form, you probably will have to re-tweak some of the other adjustments.

James.

Tube test done. Geez, found more bad ones than I'd suspected. None that were "toast", but a few that were very weak. Since the set powered up on a variac when I got it to a full raster, and worked after I replaced a few capacitors, I worked the whole thing backwards and never did a complete test of the tubes till now. Dummy.

Replaced the 6BG6, and one 6SN7, listed as "Sync amp - 2nd sync sep". The 5U4 was nearly shot, and the 6AV6 tested as very marginal in one of the three tests.

Going to order some tubes, as I'm out of 5U4s and 6AV6s....on to the resistors.

Update
 

After some more investigation, I encountered a newbie mistake. It seems that I didn't get the bumblebees on the first time around :rant:

Replacing the bumblebee cap on the horizontal linearity coil did the trick. It now locks in solidly when changing the channel.

Also replaced one of the two damper filter caps. The other, as it turns out, I have to order, as I must have used it for something else.

After the capacitor replacement, here's what changed....

Now, though it locks in solidly, I cannot change the horizontal hold at ALL. Nothing seems to affect it. It does lock in properly, but crank the horizontal hold to both detents, and you get no change. Same with the horizontal range control.

It also seems that I'm now getting a buzz in the audio. I can tune it out for the most part, but it's still there. At the beginning of this, I aligned the audio by ear, and got it perfect. Wonder if something is now off, now that I'm replacing components.

The high voltage is low also, as I'm getting blooming with the brightness control, and on screens that would have a very bright picture, such as all white...it goes out of focus. Still some screen shrinkage, but now only on the right side of the picture, and now the screen shrinkage is apparent off channel somewhat as well.

Now the one thing that I DID notice is that if I'm reading this correctly, some TV repairman stuck a .01 bumbebee in instead of a .05 at C91 in the sams, which is the other damper filter cap. Is this a possible cause of this stuff?

I realize that I'm not exactly following the suggestions, but as light bulbs light and I get the time, I've been working on the set with the parts I've got. I'm just going to order the cathode 6BG6 resistors on the next parts order, as it seems that I've got more work to do.....

Yep. In fact, now, if I crank the brightness, the whole picture will disappear.....

Tim, I'd have to see what you mean by picture dissappears, but, on horiz. hold control having no affect, congradulations. That's how the synchro lock works!
Bill Cahill

Okay, "picture" it this way ;)

The picture is expanding and defocusing as the brightness control is turned up. After the set has been playing for say 15 minutes or so, if I crank the brightness all the way up, the picture gets very dim, and just goes dark. I can get the picture to come back to a dim light by turning the brightness down, and I can get it back to its previous level by turning the brightness ALL the way down, then bringing it back up.

From my reading, this seems to be caused by insufficient high voltage, that the pulse from the horizontal output tube is too low, or the HV rectifier is weak or dead (which isn't the case).

I do know that this issue is worsening progressively as I replace capacitors and tubes, leading me to believe that it's the whole "weakest link" thing, and that it's all coming down to replacement of one stupid component. Once I nail that one component, I think everything will work perfectly.

If that's the way synchro lock works, well then, dammit, mine is perfect :)

Just discovered that the link above is the wrong schematic. Mine is a later production 9T246, and uses a 6W4 damper, and not a 5V4.

Sort of explains a few things. Time to go sort that out....

By the way, many thanks to Bill Cahill, for pointing out the above :)

You're welcome, Tim. Always glad to help.
Bill Cahill

Help!
 

Since last post, I replaced the incorrect valued cap I'd installed on the horizontal linearity coil.

Since it seems I was using the wrong Sams, I had originally put in a .01 @ 600V cap. Solid lock on horizontal. Now, I replaced the cap (C85) with a .039 @ 1 kV, and I'm back to square one with the horizontal, and being out of lock every time I change the channel.

Also replaced the .018 @ 1 kV damper filter with .02 at same rating. The bumblebee had a huge crack across the back side, which I couldn't see until removed.

Next, replaced the line filter caps (C93 & C94) with the correct stated value of .01, but upped working voltage to 630.



That said, here's my question:

Would changing the horizontal linearity coil BACK to the .01 uF from .039 cause any harm? It had solid sync lock with that cap in it, but it was wrong according to the Sams, so I switched it back in fear of causing damage.

I'd switch back to the 0.01 cap. It worked for you before, and the other caps you replaced should have no effect on the horizontal hold circuit.

No. I know what's wrong.
You were loading down the poser supply before, so, horiz. osc. was right on. You changed it to correct values, taking some of the over load off, so, now, horiz. osc. needs re adjusting.
On the damper caps. not high enough voltage. They MUST be 1KV.
Tim, you are closer than you thought. The lin. coil doesn't adjust the oscilatr. Power supply was being overloaded before. Remember? Low hv?
Set was drawing more current.
Leave the correct caps in, and, re align the horiz. osc. according to instruction.
Bill Cahill

I re-read what I wrote, and went back and corrected it. I meant to say "line filter" caps, not damper filter.