Mighty Monarch of The Air

[VintagePC]

Originally Posted by vts1134

"
Forgive my new guy ignorance but I don't know how to do that. I know how to check continuity with a meter but I'm not sure where you're suggesting I check. Could you elaborate on that some more for me?

Certainly - I had to start somewhere too, so I know how it feels But, we're always happy to explain if you don't understand. I suspect the terminology we throw around doesn't help either...

If you look at the back end of the picture tube itself, you have the end that is wired up to the rest of the set, where the guns are. Moving forward towards the wider [bell] area of the CRT, you may encounter some rings with a bunch of tabs on them [purity magnets]. You won't need to touch those at this point. Further towards the bell, around the part where the tube begins to widen, will be a cone-shaped form [the deflection assembly, AKA the yoke]. This contains the coils of wire that the set uses to move the beam of electrons within the tube. One pair of coils is for the horizontal deflection of the beam, the other pair is for the vertical deflection.

(from the picture in the first post, yours appears to be boxed in in that metal cage that rises up from the main chassis).

Essentially what you want to do is find where those are wired to the rest of the set, and use those points to test each of the vertical coils in the deflection assembly for continuity. If it's closed in, you can't tell which leads go to which coils, so you'll have to go by the schematic. I don't have one on hand, so perhaps another member can tell you exactly where they are. You should be able to locate them by wires running to the vicinity of the vertical components just mentioned (R3, R4, V13, V14).

If you get an open reading on one of them, then there's a break in that coil, and you've found your problem. If not, then the problem is somewhere else... and hopefully it is, because coils aren't exactly easy or fun to repair.

Apologies for the wall of text, but it'll have been worth it if you learned something, and my job will be complete for today

Originally Posted by vts1134

Wow! You guys are so helpful here it's hard to believe. Please don't go that overboard for me yet. Let me do some due diligence of my own before we get to that point.

It's what we do here. Everyone was really helpful while I was restoring my Fleetwood console, and some people go above and beyond to help you. I guess we are dedicated to preserving these sets too much...

[vts1134]

From what I can tell there is continuity across the coils. I looked at the schematic and I think the areas I pointed to in yellow is where to test.



I pointed to those leads in yellow below and there is continuity across those two leads. For some reason the wire on the output side of the transformer is soldered on a "landing strip"(I'm not sure if that is what you really call it but that is what I came up with). Maybe it's so you can test things easily, it certainly did make it easier for me.



Could the next step be firing the set up and testing voltage out of the vertical output transformer(T4)?

[wa2ise]

Originally Posted by vts1134

For some reason the wire on the output side of the transformer is soldered on a "landing strip"(I'm not sure if that is what you really call it but that is what I came up with).
Could the next step be firing the set up and testing voltage out of the vertical output transformer(T4)?

Terminal strip.

Anyway, be careful with the vertical output tube plate, when it's working normally it has pulses about 1 to 2KV tall.

Before firing up the set, check that you have continuity on the primary of the vertical output transformer. Likely a few hundred ohms. Oh, on the yoke, getting continuity across the secondary either tells you the yoke has no opens or the secondary has no opens. Or both have no opens. You'll have to disconnect a lead on one of these to tell for sure.

[jeyurkon]

Besides T4, you should also check for continuity on both the primary and secondary of T2 in the vertical oscillator. That one will be easy because you won't need to disconnect anything.

R3 is in the cathode of the vertical output and sees quite a bit of power which is hard on it. You should check to see that it has the correct resistance.

R4 supplies the plate of the oscillator and could be bad too, but it doesn't see as much power.

You might need to try substituting the 6C4 also even though it tests good. It might have too much grid leakage which might not show up on your tester.

John

[vts1134]

T4's secondary reads spot on at 7.5 ohm. T4's primary which is supposed to read 700 ohm is reading twice that 1.4 k ohm.
T2's secondary which is supposed to read 1.3 k ohm is reading 1.4 k ohm. I'm assuming that is well within accepted tolerance levels. T2's primary is supposed to read 160 ohm. It is reading wide open.
R3 is good to go at 5 k ohm and adjusts as I turn the control.
The tester that was used to test the 6C4 had a leakage detector and it tested good there to.

So it looks like my problem is T4 and T2? Are those parts that one can find?

[wa2ise]

Originally Posted by vts1134

T2's primary is supposed to read 160 ohm. It is reading wide open.


So it looks like my problem is T4 and T2? Are those parts that one can find?

Sometimes the open happens at the spot where the enamel magnet wire is soldered to the lead wire. The old rosin sometimes corrodes the wire, causing the break. You could dig into the outer paper tape wrap to see if that might be the case. At this point the transformer would be trash if that's not the cause anyway, so nothing lost.

As for the output primary showing twice the resistance listed, well sometimes the schematic services have errors. Or the manufacturer made a production change. But T2's primary being open would kill the vertical. So pay that more attention.

Vertical transformers are somewhat similar to audio transformers, and also power transformers. Getting the turns ratio close enough would be trial and error, also getting the phasing correct is important. I don't know what turns ratio and impedances would be correct, or what would be close enough, so it would look like black magic...

[jeyurkon]

Originally Posted by wa2ise

Sometimes the open happens at the spot where the enamel magnet wire is soldered to the lead wire. The old rosin sometimes corrodes the wire, causing the break. You could dig into the outer paper tape wrap to see if that might be the case. At this point the transformer would be trash if that's not the cause anyway, so nothing lost.

As for the output primary showing twice the resistance listed, well sometimes the schematic services have errors. Or the manufacturer made a production change. But T2's primary being open would kill the vertical. So pay that more attention.

Vertical transformers are somewhat similar to audio transformers, and also power transformers. Getting the turns ratio close enough would be trial and error, also getting the phasing correct is important. I don't know what turns ratio and impedances would be correct, or what would be close enough, so it would look like black magic...

It's a blocking oscillator. I wonder if they rely on the core saturating? Sams only gives a Majestic part number for it so it might be difficult to find a replacement.

I think your point about the connection at the lead is a good one. I've seen that a couple of times. Refresh my memory. The primary is usually the inside winding isn't it?