Mighty Monarch of The Air

[old_coot88]

Originally Posted by VintagePC

Hmm... it might well be an inaccessible direct connection between the coils in the yoke itself.

The connection is most always inside the yoke housing.

If that's the case, the best you can do for steps 2/3 is test across the yellow arrows. the result can indicate if coils are open.

Yep, but he's gotta disconnect one end, either the ground end as you suggested, or the top end. Doesn't matter which. While it's disconnected is a good time to also check continuity of the secondary winding of the transformer.
To the OP (original poster): is the capacitor across that winding (shown with dotted lines) actually in the set? If so, have you replaced it and/or verified that it's not shorted?
oc

[vts1134]

Originally Posted by old_coot88

Yep, but he's gotta disconnect one end, either the ground end as you suggested, or the top end. Doesn't matter which. While it's disconnected is a good time to also check continuity of the secondary winding of the transformer.
To the OP (original poster): is the capacitor across that winding (shown with dotted lines) actually in the set? If so, have you replaced it and/or verified that it's not shorted?
oc

Looking at the schematics I see that both coils are 2200 ohms. If I meter on my yellow arrows am I correct in thinking that it should be 4400 ohms?
The secondary of the transformer is good.
The third question about the capacitor across the winding in the schematics I cannot answer. I didn't see that before you mentioned it. It says that it's 75mmf, but it's not listed in the part list. Could that also be located inside the yoke housing?

[VintagePC]

Originally Posted by vts1134

Looking at the schematics I see that both coils are 2200 ohms. If I meter on my yellow arrows am I correct in thinking that it should be 4400 ohms?

Not quite - the schematics show resistors in parallel with those coils, and those resistors are each 2200 ohms. (Look at the horizontal coils - there's no resistance marking/parallel resistor).

The only time you'd read ~4400 ohms is if both coils are open.
If you read ~2200, one coil is open.
If you read something closer to zero, then the coils are probably OK (but you can't infer anything about the state of those resistors - see my parallel resistance calculation in the previous post).

BTW, if you can see those two resistors sticking out of the yoke or anywhere on the chassis, it gives you some test points for your red/blue arrows.

Originally Posted by vts1134

The third question about the capacitor across the winding in the schematics I cannot answer. I didn't see that before you mentioned it. It says that it's 75mmf, but it's not listed in the part list. Could that also be located inside the yoke housing?

It's possible, but doubtful. The easiest way to find it is to carefully trace the entirety of that vertical deflection line which your arrows point to and try to locate it. If you can't find it, you can do a test to see if it's there- disconnect BOTH ground points at each end of the line, and apply a few volts (no more than 20) AC to the line. (it will float, since it's not grounded at either end).
Then, see if some AC appears on the chassis ground. If so, that capacitor is hiding somewhere and passing AC (or it might be shorted). If not, it's probably not there.

Also, look at the connections running in to the yoke - there should be 4, two for vertical, and two for horizontal. (You may see only 3 if the lower ground is directly accessible from the yoke.
If you see more/fewer, it may indicate additional components have been hidden... try to trace them on the schematic to find out what those wires do.

[jeyurkon]

Since the 75mmf is inside of the dotted line for the deflection yoke it would seem that it is part of the yoke. Unless I'm looking at the wrong 75mmf.

[VintagePC]

Originally Posted by jeyurkon

Since the 75mmf is inside of the dotted line for the deflection yoke it would seem that it is part of the yoke. Unless I'm looking at the wrong 75mmf.

My understanding is we're talking about the one above his upper yellow arrow. The one you refer to is part of the horizontal circuit, whereas we're diagnosing the vertical

[vts1134]

Old Coot- Are you referring to the capacitor just above the dotted lines indicating the yoke in my picture? The schematics say that it's C70 and rate it at .25mmf at 200v. The thing is I can't find it on the schematic pictures of the top and bottom of the set that indicate where everything is. Jeyurkon maybe you can confirm that?
The schematics make me think that the capacitor would live at the end of the right hand yellow arrow in the picture below.

As you can see there is nothing there but a termination point for the wire coming from the secondary of T4 and from the vertical coils. I had mentioned this in an earlier post and postulated that maybe it was just there just to make my job easier. Is it possible that it is just missing from the set? That seems improbable to me.

[VintagePC]

To what are those two little "domino" looking things connected? (hiding behind the big resistor that's dead center.). Those are mica capacitors, and it looks like they have one lead on the left-hand connector to which an arrow points.

Also, if that orange-brown square with three leads coming out of it is connected to anything relevant, beware that those are usually a package containing a resistor and capacitor network. It doesn't look like it's attached, but just something to keep in mind. Some schematics show the separate components, some show a "magic box", and others will show the internal components outlined with a dashed-line box.

It's also possible that that capacitor is hiding somewhere in the yoke, especially if there's a nearby accessible ground point to which they could run it... It could well be bridging BOTH deflection coils to the ground connection on their other side.

Since most capacitors short on failure (unless they're special line safety caps), the AC test I mentioned will show if it's present regardless of condition... and at least knowing that eliminates some of the guesswork.

[jeyurkon]

Originally Posted by VintagePC

My understanding is we're talking about the one above his upper yellow arrow. The one you refer to is part of the horizontal circuit, whereas we're diagnosing the vertical

Thanks, that explains my confusion. That one is actually 0.25 uF, or would be if it were used.

I should have paid more attention and noticed that the discusion was about the vertical.

[vts1134]

I took an early day at work to spend some time on the set tonight. I also read through this entire thread a couple of times to come up with a game plan of tests for this evening. Here is what I'm thinking.#
I'm going to recheck the vertical height control selector.#
I'm going to check voltages on v13 and v14. I will connect my lead clips to the set and to my meter, then fire the set up for a measurement. After taking a measurement I'll remove power from the set and move on to the next voltage measurement.#
I'm going to disconnect both primary leads on my new t2 and connect them to the two leads on my variac. I'll fire the set up and turn up the variac to line voltage or robust deflection, which ever comes first.#
If deflection does not occur I will move on to OC's next suggestion of driving the coils directly with the variac. On this test I'm a bit hazy on. There is only one lead from the yoke on the vertical side. What would I do with the other lead on the variac?
After completing those test if I have time I'll move on to more.#