Ok. Let’s try this again…RCA 9TC240 Alignment

[Penthode]

Your 330 ohm shunts look similar to mine except yours look more snazzy.

Stuff like that when done goes into my alignment box where in the past i have created cable extenders and jigs to assist alignments. There is a good chance yoy will need them again someday.

[Chris K]

Well I’m just trying to be productive until Bob gets the parts to me. Once I get through this experience I have a Crosley that’s essentially a Dumont clone and the sound and video if circuits are all kinds of messed up. That would be next on my to do list. How different is the alignment protocol on different early RCA sets? I have a 630 in the works but on the shelf for now

[Penthode]

Originally Posted by Chris K

Well I’m just trying to be productive until Bob gets the parts to me. Once I get through this experience I have a Crosley that’s essentially a Dumont clone and the sound and video if circuits are all kinds of messed up. That would be next on my to do list. How different is the alignment protocol on different early RCA sets? I have a 630 in the works but on the shelf for now

The alignment is similar. I suspect the Dumont is easier. I know the RCA 630TS is simpler.

[bandersen]

Coils were shipped out earlier today. Should be there in a couple days.

[Chris K]

Thank u so much!

[Chris K]

Replacement trap coils should arrive today. I'll be getting back on the alignment procedure late tonight or early tomorrow. My intention is to replace the T-103 transformer I broke and start the coil adjustment with the VTVM over. Hopefully, Penthode will see the post and guide me once again!!!

[Chris K]

Coils are here. Thank you Mr Andersen.

[Chris K]

Replacement T-103 is in. I think the best strategy is to go back to step 6 in the alignment. I didn't do anything to change the discriminator or sound IF response curves in steps 1-4.

[Chris K]

I rechecked the discriminator and sound IF response curves anyway and they are perfectly symmetrical are the markers are correct. I think I should wait for some experiential brain input. I don't know if we should go through all of the transformer primary and secondary coil adjustments one at a time or skip to the overall look at the T-1 and T-101 trace in figure 15 and the overall IF RF response trace in figure 16 and see how much off these marker frequencies are from the service data. Maybe minimal adjustments are needed

[Penthode]

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

[Chris K]

Originally Posted by Penthode

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.

[Penthode]

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.

[Chris K]

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

[Penthode]

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.

[Chris K]

Will do. The top slug in T-103 is stuck solid. Ill use the mineral spirits. I have a variety of petroleum based penetrant lubricants, WD-40, PB Blaster etc but these slugs are compressed iron powder held together with a binder correct? I don't want to do anything that'll compromise that.