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

[Chris K]

I might have a line on a refurbished and calibrated 8601 for a very decent price. PM me if anyone is interested.
I’m going to remove the T-103 trap transformer from the chassis. It’ll be easier to work on and it’s gotta come out anyway if Bob can provide a replacement

[Penthode]

So you had no success getting the slug out? What are you using for an alignment tool? It is important you use only the correct tools.

I should have said on the outset of this adventure, normally the alignent is fairly close. The sound IF is narower bandwidth and is best gone over more concisely. The traps too need a little adjustment but they should be fairly close.

Because the video IF stagger tuned stages are pretty tuved for a broad response, there was really no need to perform the steps to spot align each stage. All that needed to be done was first sweep the overall video IF and only perform a few touch ups to get the response in the manual. I would only resort to deeper investigation if the response is bad and not easily corrected.

When looking at the overall response, and knowing where each of the stagger tuned stages is tuned to, you would look at what part there is a deficiency and adjust only slightly the appropriate stage. For example, the 22.1MHz marker is too low or not in the right place. I would first slightly adjust T103 bottom in combination with T105 bottom to try and make that part of the response correct at that point. Or the video carrier is not at the 45% point, I'd adjust T102 bottom and T104 bottom only slightly to fix it there. Only vey slight ajustments would be necessary. If that fails, then I would shunt each stage with the 330 ohm resistors and check by sweep alignment of the T1/ T101 the overcoupled Tuner to 1st IF link. In every case only a small adjustment while looking at the bsweep and if the adjustment makes it worse to back off and put the adjustment back to where it was before moving somewhere elese to adjust.

Unfortunately the adjustments now appear all over the place. You will need to highlight how much you adjusted to try and undo what you have done.

I repair clocks and watches and fine machinery. I wind and make my own transformers if the originals are damaged. I do not know what experience you have repairing these things. But the core can be removed and I believe a standard hex hole core slug can be used as a replacement.

[Chris K]

Small world…I’ve restored dozens of mechanical watches. Disassembled, cleaned in a vintage Elma watch cleaning machine, reassembled with capstone and jewel pivots oiled with 9010…regulated on a time grapher.. I used to do all that! Then I started medication that made my hands tremble just a tiny bit but it was enough. No chance of doing it anymore.

[Chris K]

So the strategy the next time would be to do whatever needs to be done preliminarily, like in this case, the sound discriminator response and the sound IF response but at that point, before getting lost in the weeds of going through each step in adjusting traps and IF transformers, just go to the overall IF/RF response curve and see how well it's aligned. If changes need to be made, then individual transformers, coils, traps etc can be individually targeted to make subtle adjustments to firm things up on the overall trace.

If this TV is so screwed up now it's basically unsalvageable, that's fine. Just this learning experience has been so valuable to me I'd do it all over again! Remember, at the beginning of this, I had never seen a response curve for any TV I've ever worked on. It looks like the reason for that was bad and unreliable equipment as much as my inexperience. Where I am and this workbench is are miles more advanced from a couple of months ago!

I'm not giving up yet. I'll get this broken slug out and find a comparable one to replace it with. I want to get the transformer, T-103, out tonight as step one.

[Penthode]

Originally Posted by Chris K

So the strategy the next time would be to do whatever needs to be done preliminarily, like in this case, the sound discriminator response and the sound IF response but at that point, before getting lost in the weeds of going through each step in adjusting traps and IF transformers, just go to the overall IF/RF response curve and see how well it's aligned. If changes need to be made, then individual transformers, coils, traps etc can be individually targeted to make subtle adjustments to firm things up on the overall trace.

If this TV is so screwed up now it's basically unsalvageable, that's fine. Just this learning experience has been so valuable to me I'd do it all over again! Remember, at the beginning of this, I had never seen a response curve for any TV I've ever worked on. It looks like the reason for that was bad and unreliable equipment as much as my inexperience. Where I am and this workbench is are miles more advanced from a couple of months ago!

I'm not giving up yet. I'll get this broken slug out and find a comparable one to replace it with. I want to get the transformer, T-103, out tonight as step one.

The set is far from screwed up. I would stick with it as it is a great learning experience. And for me that is what it is all about: learning new things. I smile because once you have mastered this set you should have the experience to work on other stuff like this.

[old_tv_nut]

Originally Posted by Penthode

The set is far from screwed up. I would stick with it as it is a great learning experience. And for me that is what it is all about: learning new things. I smile because once you have mastered this set you should have the experience to work on other stuff like this.

Ditto! You have made progress all through this and never reached a state anywhere near "unsalvageable."

[Chris K]

Originally Posted by Penthode

The set is far from screwed up. I would stick with it as it is a great learning experience. And for me that is what it is all about: learning new things. I smile because once you have mastered this set you should have the experience to work on other stuff like this.

I know and thanks for the encouraging words. Not sure what to do about broken parts though. These 3 trap units are the same part number...they are just tuned differently.

[bandersen]

Ditto - not even remotely unsalvagable. Heck, you don't even need some of the traps for it to work. There aren't going to be any adjacent channels in your area.
By the way - this is why I don't align most sets and when I do it's often just the sound. Great learning experience none the less.
Yes, these are capable of excellent image resolution but that also requires you to feed it a signal with good bandwidth. Most sources are going to be band limited because of color info. There are ways around this but that's a topic for another thread.

[Penthode]

I would beg to differ on one point. The traps especially in this set help shape the overall bandwidth. If you want to achieve the full four megahertz, setting the traps as prescribed accurately is important. And with the HP equipment you can set it as good or beter than before it left the factory.

T103 is a little different: the trap set to 21.25MHz and this trap provides the sound IF take off point.

So providing the center tube is clear, the new slugs should fit.

I do have to admit that I recall over 50 years ago I took apart the T103 in my set for a simiar problem. The Canadian version I have, unlike the US version, uses a brass threaded screw to the ferrite core, similar to the width coil on your set. The bottom threaded clip insert snapped when I tried to adjust it. I had to remove also T103, unsolder the tap wire on the middle othe trap and take pull the black bakelite cover off to access the inside. once apart, I had to unsolder the fine wires to the tabs to pull the coil off and replace the broken clip which was nested at the bottom of the coil in the brass cup.I replaced it with a reshaped spring matching the original shape, I reassembled solder back the tap wire and reinstalled the transformer. The set aligned very well using the equipment I used then (having to set a generator marker frequency interpolated between beating with a crystal harmonic). In those days of a crowded VHF band, I had to ajust slightly the adjacent channel traps using off air signals. Eg. I would receive a weak channel 10 from WHEC Rochester. The fine tuning because it is of a split sound design is for best sound. So the fine tuning on these sets is very precise. Once set for best sound on channel 10, we had strong adjacent channels on CFTO channel 9 Toronto and CHCH channel Hamilton. So to minimize adjacent channel 9 sound in picture, I would touch up slightly the 27.25MHz traps and for CHCH channel 11 video ineterface in channel 10, I would slightly touch up the 19.75MHz traps.

It is with this alignment much later in 2009 I could use the set to DX when living in Southern Illinois. Look at the snapshot of WPTB Channel 2 West Palm Beach Florida received 1500 miles away despite a strong adjacent WSIL channel 3 Carterville Illinois located about 10 miles away. No other set, even much newer sets had the adjacent rejection capability of this RCA chassis!

The two photographs below show on off air channel 8 from KAET Phoenix. The four Megahertz resolution brings out a lot of fine detail. The second photo is a weak WPTB channel 2 received 1500miles on this set witha standard antenna atop a 50 foot mast direct to the receiver tuner with no preamp.

[Penthode]

With all that said above, there is of course no more over the air. But the traps accuracy, especially the 21.25MHz and 27.25MHz traps are important to obtain the correct Video IF response shape.

[Chris K]

So I was able to salvage one core slug out of the 2 in T-103. At this point I don’t have another slug with the coarse thread pitch of the original. I’ve looked on eBay for similar substitutes with no luck. There is a Merit trap coil that is available that’s close. I think this trap is 21.25/22.0 and the Merit trap is 21.25/21.8. I’m wondering if that’s close enough to do some creative tuning to get it to work in the RCA

[Penthode]

The trap in the RCA is mutually coupled to the 21.9MHz tuned stage part of the stagger tuned strip and you really must replace it with the same. It will be easier to fix the RCA transformer.

Looked like the other slug is smashed. Did you damage the coil former encased by the bakelite cover?

If the rest is intact and you need only the core. If the only replacements you have have a finer thread but is of the same diameter, that would work as the slug make the thread in the tube.

Can you show some more pictures? What is the diameter of the slug?

[Electronic M]

Don't know if the coils in a KCS-47 will have the slugs you need, but I did scrap one and kept the coils. If I can find them and one has what you need I'd sell it.

[Penthode]

Originally Posted by Electronic M

Don't know if the coils in a KCS-47 will have the slugs you need, but I did scrap one and kept the coils. If I can find them and one has what you need I'd sell it.

I believe the slugs in a KCS47 are the same going back to the KCS28. So that should work.

[Chris K]

Originally Posted by Electronic M

Don't know if the coils in a KCS-47 will have the slugs you need, but I did scrap one and kept the coils. If I can find them and one has what you need I'd sell it.

That would be great Tom. I’ll take whatever you have. PM me. Bob too. My fear is these other slugs have been manipulated way too much and may be fragile as well.