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  #31  
Old 05-10-2011, 12:46 AM
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After you check the deflection coil, check R3, the vertical linearity control and R4 the vertical size control.

I assume you've already checked V13 the 6C4 and V14 the 6V6.

The way they've drawn the alternate circuits is confusing to me and I'm not sure where this section is getting it's B+.

I might have to pull my chassis and see what they really did.

John
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  #32  
Old 05-10-2011, 03:52 PM
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"The easiest place to start is with the vertical deflection coils (the ones on the neck of the CRT) - check them for continuity with a multimeter."

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?

"After you check the deflection coil, check R3, the vertical linearity control and R4 the vertical size control.

I assume you've already checked V13 the 6C4 and V14 the 6V6."

I've tested V13 and V14, they both check good. I've also adjusted R3 and R4 to no avail.

"I might have to pull my chassis and see what they really did."

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.
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  #33  
Old 05-10-2011, 06:09 PM
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Originally Posted by vts1134 View Post
"
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

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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...

Last edited by VintagePC; 05-10-2011 at 06:18 PM.
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  #34  
Old 05-10-2011, 08:56 PM
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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)?
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  #35  
Old 05-11-2011, 12:21 AM
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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.
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  #36  
Old 05-11-2011, 10:54 AM
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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
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  #37  
Old 05-11-2011, 12:10 PM
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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?
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  #38  
Old 05-11-2011, 01:17 PM
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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...
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  #39  
Old 05-11-2011, 03:22 PM
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Originally Posted by wa2ise View Post
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?
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  #40  
Old 05-11-2011, 04:53 PM
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I cut through the transformer in haste and cut too deep totally screwing up the winding so I don't know if it was the leads or not. I did pick up a new vertical block oscillating transformer to replace it though. The impedance on the primary and secondary are lower than the original but I put it in and I'm going to hope it'll oscillate. I may have to tweak the circuit with resistors inline with the new transformer to make it linear but I'm crossing my fingers it'll be ok as is.



Again I don't have a variac at home so I'll have to wait until tomorrow to fire it up and see what how I did.
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  #41  
Old 05-11-2011, 06:26 PM
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Sadly, if it doesn't work, adding resistors won't help- the transformer's magic comes from the # of turns of wire inside, not from the resistance of the coil; less resistance probably means fewer turns, unless the wire gauge is thicker than the original. (if you add a resistor, you make an RL circuit which behaves very differently from a coil by itself)

Also, if you can get replacement "magnet" wire [copper wire coated in enamel] of the same thickness as that of the original transformer (a yoke from a crap modern tube TV is a great place to get some), you could always give re-winding it a shot. It requires some patience and finesse, but it couldn't hurt to try if you can't get a good replacement for a reasonable price (i.e. reasonable hourly pay for how long you spend to wind your own), or are up for a challenge. It seems daunting, but it's not excessively difficult to try.

To do that, the two magic numbers you need are a) the # of coil turns, and b) the total length of wire. Both of these can be obtained while you unwind the original. As pointed out before, you also need to pay attention to the polarity (winding direction) of the original. If you can match the winding pattern of the original, even better! Note that if A number of turns does not use near B amount of wire then something's wrong and you need to try again, unless it's because you use a different winding pattern.

[I managed it with just matching the length of wire and winding pattern in an oscillator coil for my Fleetwood console (wire was ripped beyond repair, so I couldn't count turns and had to lay the pieces end to end to get length), and it worked... but I don't doubt a TV circuit is much more finicky, so YMMV]. I'd be happy to offer more details if you have questions... but no guarantees since I've only re-wound one coil myself, and that may just have been dumb luck!

Last edited by VintagePC; 05-11-2011 at 06:32 PM.
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  #42  
Old 05-11-2011, 06:59 PM
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I looked in my Merit catalog and they do list a replacement. It's an A-3003.

The A-3003 has a turn ratio of 1:4.2, the A-3006 that you have is 1:3.5.

www.oldradioparts.com has the A-3003 for $7.00. They have a $25 minimum order.

John

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Originally Posted by vts1134 View Post
I cut through the transformer in haste and cut too deep totally screwing up the winding so I don't know if it was the leads or not. I did pick up a new vertical block oscillating transformer to replace it though. The impedance on the primary and secondary are lower than the original but I put it in and I'm going to hope it'll oscillate. I may have to tweak the circuit with resistors inline with the new transformer to make it linear but I'm crossing my fingers it'll be ok as is.



Again I don't have a variac at home so I'll have to wait until tomorrow to fire it up and see what how I did.

Last edited by jeyurkon; 05-11-2011 at 06:59 PM. Reason: spelling
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  #43  
Old 05-11-2011, 07:04 PM
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but I put it in and I'm going to hope it'll oscillate.
If it doesn't oscillate swap the leads on either the primary OR the secondary, but not both.
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  #44  
Old 05-14-2011, 08:29 AM
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Tried the transformer and got deflection!

I'm emailing oldradioparts now to enquire about the correct transformer. Does any one else need any parts and want to go in with me to meet the $20 minimum order? I suppose I could always just give them $20 for the transformer instead of $7.
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  #45  
Old 05-14-2011, 04:51 PM
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Tried the transformer and got deflection!

I'm emailing oldradioparts now to enquire about the correct transformer. Does any one else need any parts and want to go in with me to meet the $20 minimum order? I suppose I could always just give them $20 for the transformer instead of $7.
You might look at his book and magazine section. You might be interested in some of the TV related ones.
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