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Old 10-05-2024, 08:31 PM
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Penthode Penthode is offline
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I think first checking and confirming the traps are correct. Following the RCA notes is best. But do it slowly and step by step.

Remember that it is easy to tune incorrectly and make the IF strip break into oscillation. We it is oscillating, it will give false reading. As pointed out, you and test if it is oscillating if you get a large signal at the video detector when the signal generator is off.

If it does break into oscillation, the notes suggest the solution.

The main thing is if the slugs appear tight, don't force them. Stop and let's discuss
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Old 10-05-2024, 08:59 PM
Chris K Chris K is offline
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Quote:
Originally Posted by Penthode View Post
I think first checking and confirming the traps are correct. Following the RCA notes is best. But do it slowly and step by step.

Remember that it is easy to tune incorrectly and make the IF strip break into oscillation. We it is oscillating, it will give false reading. As pointed out, you and test if it is oscillating if you get a large signal at the video detector when the signal generator is off.

If it does break into oscillation, the notes suggest the solution.

The main thing is if the slugs appear tight, don't force them. Stop and let's discuss
Yes top of T-103 is not turning. Using a plastic tool with the tip formed to fit exactly the slot on top of the slug.
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Old 10-06-2024, 09:57 PM
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Penthode Penthode is offline
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Yes I anticipated you might run into this. I would be inclined to remove the slug and use it on the original transformer. That is if you did not damage the original transformer when trying to remove the broken slug.

To loosen and remove the slug, you might try first a drop of mineral spririts to dissolve the wax.

A further solution which I have done on these sets is to remove the transformer and disassemble it. I use a heat gun gently on the tube holding the slug and heat it until the slug moves. I remove the slug, checheck the tube and ensure the slug moves with sufficient friction to hold it in place but loose enough to adjust.

Try the mineral spirits (turpentine) first. Add a drop and leave it a few minutes and then try to adjust.

The other slugs on the other transformers I assume are near where they originally were and can move enough for the touch up adjustment?

Remember, there is nothing magic about these transformers. I have replaced and made many coils and transformers for various sets. I have successfully remade the quadrature coil used in early Zenith color sets which are prone to going brittle and snapping. I have even reused the original wire failing to have on hand the correct gauge wire. It is just logic and perseverence.

Last edited by Penthode; 10-06-2024 at 10:05 PM.
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Old 10-06-2024, 11:48 PM
Chris K Chris K is offline
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I will try the mineral spirits first very conservatively. I have disassembled several coils like these in the past and I’ve been surprised at how much space is in these Bakelite shells. The coil windings are around a cylinder that’s thinner than a pencil. The damn problem is finding the sweet spot between downward pressure on the tool enough to keep it seated in the slot without so much the core is pushed out of the threads and down. This is really the only adjustment that’s significantly displaced from where they were originally. I have pictures of the chassis bottom and the screw type if coil threads are the same as they were before I started messing this up. Let me see what a little lube will do. I don’t want to put a drop of spirits in the core. I think I’ll soak a Q Tip in it and place the cotton end in the tube and just press a small amount out
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Old 10-07-2024, 09:34 AM
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Penthode Penthode is offline
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I do't believe you need to provide much downward pressure if the screwdriver tip properly seats in the slot. With a good slug removed, you may wish to check the fit and alter the tool as necessary to provide a good fit.
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