I would check resistors around and downstream of the oscillator, R65 and R66 especially, also R67 and R68 while you're in the neighborhood. You have partial deflection, suggesting that your oscillator is working somewhat, but its sawtooth is attenuated. You have already replaced obvious capacitors in that area. There ain't much left but resistors, so I would check those to eliminate 'em from the equation.

Also, C48 is the coupling cap for the oscillator. With a value of 4700 pf, I suppose it is a mica, but micas do croak sometimes.

Phil Nelson

I tested R65-R69 previously and they all passed. I'll look into C48.

Any chance somebody could post the schematic of the entire vertical section? I re-read the thread to see if I'd missed it, but dint see it. oc

Here ya go.

http://antiqueradio.org/art/temp/Majestic1600.jpg

Grid and plate voltages of the oscillator tube are low. It would be interesting to sub that tube, or even look at things upstream.

Phil Nelson

Arr. Now we're cookin'. First assuming the output transformer and yoke coils have proved good, I wouldn't worry about the oscillator just yet, but first prove whether the output stage is working or not. Just inject some AC at the control grid (pin 5) of the 6V6. No need to disconnect anything, since everything 'upstream' is high impedance and DC-isolated by C50. Just run a jumper from pin 7 (heater) to pin 5. That'll put 6.3VAC directly on the grid, which should give a few inches of deflection (and it should vary somewhat with the linearity adjustment). If it does, that would indicate the output stage is working, and the failure lies upstream in the osc. area.
oc

Should I get a few inches of deflection total? or a few inches more deflection than I have already, which is already a few inches?

A few inches total, since all the grid will be "seeing" is the 6.3VAC. Also, before doing this, try grounding pin 5. You should get a flat line. Then do the 6.3 jumper trick. How does this deflection compare with what you already had?

OC- Grounding pin 5 did indeed give me a flat line. Jumping pin 5 to pin 7 gave me a lot of deflection as you can see below. The two pictures below display the range I got from adjusting the linearity adjustment.

http://farm4.static.flickr.com/3274/...09f1bc924c.jpg

http://farm3.static.flickr.com/2229/...67bdf6394b.jpg

Very exciting to see something different! Also kind of interesting to see 60hertz through the second picture, which I only noticed on the picture and not looking at the set itself. Thanks so much to all of you for all the help again, I'm having such a blast with this!

:banana::banana::guitar:Hey cool. Now in one fell swoop you've proved that the output stage, transformer and yoke are all good, and the failure lies back in the osc. area. Basic isolation technique 101. :D

I spent some time looking over the schematic to get familiar with things down stream from the vertical output stage. I traced each connection from point to point on the schematic and on the set itself and found my first mistake. I had connected the secondary of T2 to the wrong place. I connected it correctly and got this.
http://farm6.static.flickr.com/5186/...93f5b52535.jpg
I also found the the ion trap was a bit out of place so I tried to align it as much as I could by site. I also adjusted the vertical controls to see if I could get an aligned picture but the picture above is as good as I could get it. I'm not sure if you can tell by the picture but the bottom of the picture is brighter than the top, and the left hand side of the screen is brighter than right. Any ideas on where to head next?

Looks to me as though something is clamping the vertical sweep wave... i.e. it's rounded off on the bottom instead of a nice sawtooth.I'd be tempted to say it's a passive component (resistor, capacitor) that's the culprit, but if that's the case, you'd see it at the top of the sweep too.

Does anything happen if you adjust the vertical centering control, and if so, can you bring the top edge of the raster in to view?

I don't know where the vertical centering control is on my set. I don't see mention of it in the schematics.

Try jumping a known-good electrolytic across C1 (the 100mf one going to the cathode [pin 8] of the 6V6). That's exactly the effect you'd see if that cap were open. oc

The bottom is brighter than the top because the vertical linearity is way off. It could be an adjustment, or a symptom of another problem.

That's correct.
An open (or absent) electrolytic (C1) on the cathode of the output stage will cause severe non-linearity with insufficient sweep at the bottom. I'm wondering too if the problem isn't related to T2 (the coupling xfmr.) being different from the original.. and also if this difference is gonna cause the vert. frequency to be off. oc

I don't have another 100uf cap to replace C1B, nor do I have a capacitor tester. What I did do was fire the set up and take a visual check, then remove the cap that is in place and fire it up again. There was no change at all in the picture. I'll get another 100uf cap and try swapping it in.

Seems to confirm what everyone says... Fingers crossed once you get that replacement! :)

New cap same problem :(. Might R3 be the problem? I've tested it for impedance but could it fail in another way? I'm going to try again to get the real replacement for T2 to eliminate that from the equation also.

Well doggone. Did you connect the + end of the cap directly to pin 8, and the other end to ground? (Some foreign-sourced electrolytics have an arrow pointing to the [-] end of the unit, which can trick you as to which polarity it's signifying.)
Not likely if it measures (approx.) 5K and shows no dead spots or drop-outs throughout its rotation.

R3 reads 5k on the high side and just a couple of ohms on the low side. There are no dropouts or dead spots in the rotation. C1B used to connect to pin 8 with a wire. I removed the wire since I was no longer using a multi stage can and now have the electrolytic directly on pin 8 and the negative right to ground. Here's hoping a new T2 will be the answer.:worried:

If you have the proper resistors to match the new T2's resistance to the original, you can try that too. I doubt it would work, but if it does, it might save a few bucks on trying to locate a matching part elsewhere.

New transformer same problem :headscrat. I will return to the schematic for component by component tracing soon.

Sounds like it's time to break out the scope :)

Tracing waveforms can get you a good idea of where the problem lies. Do you have a reference of what they should look like? (Usually in a Sam's)

Also, if you have substitute tubes, it may be worth trying those too. Some sets drive them to their design limits, and the result is a set that works perfectly with one tube, but not another that is slightly out of spec. Both tubes will still test good, of course, so the easiest way to find this problem is what's called the "tube roll" (swapping tubes in the problem areas with another one).

I have found that to be the case with oscillator tubes, especially. Sometimes I have had to swap in several horizontal oscillator tubes before finding one that the TV "liked."

Speaking of oscillators, are the voltages on V13 still as far off as before?

Looking at waveforms with a scope seems sensible. This schematic doesn't give models, but you could start by looking at the grids of V13 (oscillator) and V14 (output) and posting photos of what the scope traces look like there.

Phil Nelson

Well tarnation. Just out of curiosity, what voltage are you getting at the low/wiper end of the vert. size control? oc

**I forgot about the recent progress and was commenting about an earlier state.** :o

Um.. just to reiterate what was suggested back in post# 62, the plate load resistor of the
V.oscillator is a very common failure point and should be double checked if you haven't already done so. Now that we got the schematic to look at, that would be R66, 470K (half a megohm +/- 10% or so).

And does the V.size control (R4) measure correctly at 2.5 meg or so?

How about the voltage at the bottom of R4? Since it's supplied from B boost, it should probably be somewhere around 400-450 V.

oc

I think I might have found my answer... Well let's all cross our fingers and hope so :yes:. Being a rookie at this restoration business I mistook black beauty capacitors for resistors. I missed five of them in the set including C49- the vertical discharge cap. I have the replacements on order and I'll let you know if that's the solution.

R66 is good to go btw.

Sounds promising. They look pretty but are evil.

But they're so pretty!

Yeah, C49 could sure as heck be pulling down the 6C4's plate voltage if it's leaky. Just for the heck of it, try disconnecting C49 and see if the plate voltage goes up. That resistor in series with it (R67), what does it measure? It's kinda hard to read from the print but it looks like it says 8K.

With C49 disconnected, what happens to the sweep?

oc

I know R67 reads good, I checked that off of my list. I'll disconnect C49 and and report results but I can't do it tonight. I've already started :beer: and I made a rule, no TV time after beer :D.

Aww, but that is when it is the most fun! Last new years(or was it christmas) I had a couple, and droped a Color chassis on my foot. It took me a while to realize that it cut me!... the little bugger.

Back when I encountered my first set with those bumble bee caps(it was a zenith transoceanic) I made the exact same mistake. To this day it still has those caps in it.

Tom C.

After you get the C49 thingy sorted out, take another look at the 6V6 output stage and see if it's "version 1" or "version 2".

With the revisions shown in the schematic, the output stage itself has seen a fair bit of engineering fudgery, probably to optimize linearity.

In "version 1" the plate and screen (pins 3 and 4) were simply strapped together. Kind of unusual.

In "version 2" the screen is supplied from B boost (again kinda unusual), through added-in resistors R96 and R97. Cap C69 is added from the plate to screen, probably to tailor the waveform. And bypass cap C71 is added to filter the boost line.

If your set has "version 2", those two caps should definitely be replaced if not already. And the two resistors checked for value. oc

Because I'm not afraid to look like a rookie here, and in the hopes of teaching some one else, I'm going to tell you what I didn't do. I didn't test the tubes in this set (except the two vertical tubes, and even then I don't think the tester was good) until today. I know some of you will be thinking :wtf:, I am thinking :wtf:. My new rule is tubes will be tested before I even begin recapping. Ten tubes were shot... 10! I came home to replace the tubes in question and found two things. #1- my set uses V10 and I don't have a 6AT6. I had a 6AV6 left after replacing all of the other tubes. I'm not sure if I had a mix up at the shop when I was replacing tubes, or if a 6AV6 was in V10 in the first place. At any rate I simply left V10 out and fired the set up. #2- When I give the set more than 90volts I start to hear a sound in the high voltage cage that I don't like. The sound get worse as I cranked voltage higher. It kind of sounds like a very faint snap...snap...fsst...crackle...fsst..snap...crackl e. It could just be a different sound and I'm paranoid but it sounds like something is eating itself. I don't know how to test such a thing as I can't tell exactly where it's coming from. I'd rather not "test" by waiting until what ever it is to finish eating itself and whatever other components around it that it wants to take with it. Any thoughts on what the noise could be?
BTW the vertical is now full height.
Sorry to all of you here for wasting trouble shooting time by not completing step one.

The 6AT6 and 6AV6 are interchangable. if the 'V6 is good just leave it in.

Do you smell anything burning, or smell ozone? Is the aquadag (conductive coating) on the CRT securely grounded?

Hey, you didn't waste anybody's time so don't feel bad :) We all enjoy the heck outa this stuff no matter whut.

Where is this connection?

I may not have wasted any ones time, but it was a forehead slapper for me that's for sure. It sure has been a learning experience on my first set.

When the CRT bell is coated with aquadag (black graphite-looking stuff), there is usually a pair of thin wiry springs (sometimes one spring) that push onto it when it is fully installed. These connect to chassis ground, often through the metal yoke housing.

If the sound is a sort of faint hiss or fsst noise, it might be corona (high voltage arcing) somewhere inside the high voltage cage. Did you ever open that cage and clean the stuff inside? It's often covered with very fine, sooty dust. Rubbing alcohol cleans it off easily.

If the inside of the cage is clean, you could open it up and briefly power up the set with the room dark. HV arcs look bright blue or blue-white. If you see any, note the location and power down immediately, then investigate.

Phil Nelson

I remember reading this from your 630ts. When I first heard the sound this is what I thought of so I took a look at the area through the bottom of the set with the lights out and couldn't see any arcing. I'll try looking at it from the top of the set tomorrow and see if I can't pinpoint any arcing.

Found the source of the noise. It is V18, the high voltage rectifier. The base of the tube is sparking bright light blue. Could this be a bad tube itself, or possibly a fault elsewhere causing the problem? R89 and R95 are both reading right on.
I'm sorry to be such rookie but I'm still don't quite get the ground connection for the aquadag. I've google searched the spring connections and saw a couple of examples but my set doesn't have anything like that that I can see. The only connection that I can see is a rigid wire connected to ground with a u shape around the high voltage wire. Is this supposed to be making a connection for the aquadag, or is it just to hold the high voltage lead in place? I've tried to show as much as possible of the tube in the three pictures below.
http://farm4.static.flickr.com/3009/...d5be2bed5c.jpg
http://farm6.static.flickr.com/5065/...69fe9c32a4.jpg
This next picture you can see the high voltage lead and the wire I mentioned with it.
http://farm3.static.flickr.com/2729/...80d76cf28c.jpg