Rca Ctc-15
 

Another project I decided to start is a CTC-15. I have two of them in the garage... one in a metal cabinet and one in a Beauchamp wood cabinet. Currently, neither one has a CRT. The plan is to put the better of the two chassis into the Beauchamp cabinet, which will be stripped and refinished.

Since i didn't get very far with the Philco today, I decided to bring up the 15 on the variac. (I have a feeling that I'll be jogging back and forth between these two sets) I was glad when it started picking up audio from our local channels by the time I got it to 80 volts... at least I know the first few stages are operating. After finally getting it up to full power, B+ voltages looked good and audio was good and clear. I found one lytic that was slightly warm, but not too bad to worry with at this time.

Before powering it up, I found a couple of wires that had burned in two from being next to a 10 watt resistor. Also, looks like the HV anode lead needs replacing due to a crack in the insulation.

CTC-15 Update
 

Tonight I decided to hook up a picture toob to this CTC15 chassis. The only CRT I felt safe plugging in was in a wooden CTC11 set... this particular set's toob has severe cataracts and is weak on one of the guns, but works. I yanked the 11 chassis out, and half-ass squeezed the 15 chassis partially into the cabinet. It's not pretty, but will do for testing purposes.

After plugging the horz output tube back in, I had the pleasant sound of soft HV crackle, and then light on the screen with stations tuning in good... so good that I actually got a few Houston stations 90 miles away in addition to our own by only using an 18 inch jumper wire as an antenna.

The picture looked a bit out of focus, but that's likely from the cataracts... they're pretty bad all the way to the center of the screen. Looks like the color circuits are working as well. I let it run for 15 minutes and then decided it was way past bedtime.

Tomorrow I'll run it some more and do a few checks here and there. The chassis needs all of the pots cleaned, but was out of cleaner spray so I'll get some in the morning. Still got a few caps to upgrade with orange drops.

Since things are looking positive for this chassis so far, I'll get started on stripping the cabinet that it's going in. Feels good to know I'm making progress!

I was going to take some pictures of tonight's progress, but realized I left my camera at the camp today. Oh well. Here's a photo of the 11 that the 15 is squeezed into. As you can see, it needs some serious eye surgery! :eek:

This morning I ran the 15 some more. After running it for 30 minutes, the only problem I found was the flyback running hot. Man I hate having to deal with HV problems! When I yank the chassis back out, I'll check the caps under the hz-output tube.

Any other suggestions?

Re: CTC-15 Update
 

Charlie,

How can you tell just by looking at the front of the set the CRT is defective? (BTW, what are cataracts on a picture tube? I've seen them mentioned in threads here, but never really knew what kind of defects they actually are [never heard of them until now], even after 30-odd years of experimenting with old sets back in my hometown.) Looks to me like the screen is just very dirty (filthy, even), and a good cleaning should have it looking a lot better.

I couldn't believe it when I read in your post that you were getting not only your area's local Beaumont/Port Arthur, TX TV stations, but also Houston stations 90 miles distant, on your RCA CTC15, just using an 18-inch alligator clip lead. The signal propagation conditions that day must have been incredible or even phenomenal. I am an amateur radio operator and have gotten incredible distance reception on both my radios and TVs in the summer, but I had external antennas on my sets at the time. My best distance reception on TV was KTWO-TV, the then-NBC affiliate in Cheyenne, Wyoming, one summer about 15 years ago, when I still lived in suburban Cleveland, but I have also received one of your area's local stations (channel 4 in Port Arthur, Texas) during a temperature inversion about 25 years ago, give or take a couple years. The reason I was able to receive so many stations in the Southwest is that my TV antenna was aimed in that direction (the local TV stations in my area at the time, and where I live now as well, all transmit from a Cleveland suburb some 45 miles southwest of here). When the TV bands opened up to the Southwest, the floodgates opened up and I would get incredible reception from Wyoming, Texas, Oklahoma, Florida . . . literally, you name it. The pictures, as long as they lasted, were often good enough to watch, but much of the time I would get a hodgepodge of stations, almost impossible to decipher. When one signal would eventually fade out, another would appear underneath it, and so on.

I have cable where I live today (TV reception from Cleveland, at least on VHF channels, is fair to poor at best here without it or a satellite hookup, even with a fringe-area outdoor antenna with an amplifier; in fact I cannot get one channel, NBC channel 3, on an antenna--the irony, however, is that most of the Cleveland UHF stations come in clear as a bell even on rabbit ears), which has pretty much put the kibosh on distant TV reception for me (I cannot use outdoor antennas here as I live in an apartment building). However, a couple summers ago, there must have been a temperature inversion, as channel 4 (one of our local UHF stations is downconverted to that channel by the cable company) was a mess, with Venetian blind interference, co-channel, you name it. Couldn't make out what stations were wiping out the local station (UPN channel 43, downconverted to 4), though I think it may have been either WDIV NBC4 in Detroit or WCMH NBC4 in Columbus, Ohio (out here on the fringes of the Cleveland stations, one can never tell what might appear on vacant channels, or between the local stations on the FM radio dial for that matter, during an inversion or even during normal weather in the spring and summer). I called the cable company and was told the problem was due to weather conditions, as I had suspected all along.

BTW (2): I just took another look at your CTC15 in the CTC11's cabinet. Looks to me like the 15 fits rather well in there. Am I overlooking something? I ask this because it seems to me you've managed to fit the CTC15 completely into the other cabinet, not just partially (as you mentioned).

BTW (3): Once you refinish that cabinet you will have one fine piece of furniture. RCA offers only one console TV today, as does GS/Zenith; I suspect the cabinets are made by a cabinet maker in North Carolina (Thomasville comes to mind). However, most TVs today are table models; as I've mentioned elsewhere in this forum that most folks wanting consoles these days simply get an entertainment-center cabinet and fit the TV, VCR and possibly a bookshelf stereo in it. These cabinets are nice, but the large ones can take up an entire wall (a friend of mine has his TV, VCR and stereo in one of these monsters; I've seen it--yes, it takes up a good part of a wall in his family room). I put my own TV, VCR and cable box on a small utility cart just a tad smaller than a small console; it all fits nicely in a corner of my apartment (my stereo is immediately adjacent to my computer, with the speakers on the floor on either side of my desk; my avatar shows the TV installation.)

BTW (4): The armoire-styled console TV/stereo units made by RCA and Magnavox in the late '60s would have been great for people living in apartments as small as or even smaller than mine, as I've mentioned here before. I've often wondered why RCA doesn't offer this style of cabinet, with an up-to-date TV in it of course, today. (The company does have one console in its deluxe line of 27-inch TVs, but it is a standard floor model.) If I were a betting man (which I'm not), I'd be willing to bet the vertical console design, even without the stereo, would be an instant hit with apartment dwellers or folks with small living rooms wanting large-screen CRT-based TVs.

21FJP22's get this condition because the safety glass is coming unglued from the face of the CRT. 21AXP's, CYP's, and FBP's do not use the glued on safety glass.

The tube itself can be very good electronically.

If you'll look towards the bottom of this page, this is wide discussion on cataracts. In fact, there is a photo of Rob removing the safety glass.

http://www.audiokarma.org/forums/sho...5&pagenumber=3

Yes, every now and then I can get some really good DX-ing on TV. I have seen nights in which the distant stations are almost as clear as the locals. Several years ago, I was able to pick up Corpus Christi 300 miles down the Texas coast... for an entire week! That was really somethin! In fact, at night it was causing problems for picking up the locals here. The channel 6 in Corpus was bleeding thru the channel 6 here at home. Several months back, I picked up what I believe was a station in Mexico. At first, I thought it was a Mexican station out of Houston... till I realized the call letters started with neither a K or W.

Don't waste your time doing it with chemicals and such.....

http://www.audiokarma.org/forums/sho...?threadid=6740

Jeff,

The photo here shows a 21FJP22 with severe cataracts. As you can see, the only place in which the glue is still intact is the clean area in the dead center.

If mold or mildew starts to get between the two pieces of glass, it turns black like this one did. Sometimes, it may be light cataracts, which is the greenish looking "halo" seen around the outer edge of the tube.

If you have a FJP with cataracts and good emisions, you can take on the task of removing the safety glass, and then you have a FBP.

This can happen with some of the early rectangular tubes as well, but in most cases it is only the green halo.

Here is a photo of the 15 chassis squeezed into the 11 cabinet. It almost fits! I did this only for testing purposes since I dont have a 15 cabinet that has a tube installed in it.

The other photo you saw still had the original 11 in the cabinet.

Flyback Troubles
 

Went out to toy around with this CTC15 chassis some more. Last time I ran it, the flyback was running hot after 30 to 45 minutes of operation.

I checked the current off the 6JE6 HO tube. It was running about 220ma. The schematic says not to let it run over 210. I adjusted it down to 205ma, but the flyback is still getting hot enough to where the wax bubbles in the middle.

Everything else seems to be running just fine. Any suggestions?

Sometimes the 6BK4 circuit can load the HV down too much, causing the flyback to overheat...check the voltage drop across the 1000 ohm cathode resistor...should be between .8 and 1 volt (800-1000 microamps). If it is more, then check the HV adjustment, also use a probe on the HV if possible to see if it is low because of excessive 6BK4 current.

Resistors in the 6BK4 cathode/grid circuit can change value, causing excessive current draw.

Chad,

Thank you for the pointers. I never really cared for dealing with HV problems, and luckily they're few and far between for me.

I've made the checks you mentioned, and so far have made a few adjustments here and there. The 1000 ohm resistor you mentioned is not included in my set. From the Sams diagram, it looks like it isn't used in all of the models.

Since making these current adjustments involves using two meters at the same time, I made a trip to Rat Shack and bought another. Before that, I was having to joggle my meter back and forth between the HO tube and regulator.

My first readings on the cathode lead of the regulator was roughly 1500uA... far more than it needed to be. It would fluctuate some, but in any case it was somewhat high. A local friend suggested changing the HV rectifier, and so I did. This brought the current down to to 950uA initially, but I notice that it fluctuates and slowly falls as the set continues to run. In fact, it slowly falls as far down as 300uA after operating nearly an hour. In the meantime, Sam mentions not letting it fall below 850. I did try changing the regulator tube, but doing so had no affect.

The 1.5 meg resistors in the regulator circuit check right on the money.

The HV was running at 24,000 volts, so I tuned that down to 23,000. It seems to be pretty steady.

I've got the HO tube current tuned down to 202mA, and it's pretty steady as well.

With all this being said, the flyback still gets hot, but not near as bad or quickly as before. Before these adjustments and changing the rectifier, it would get damn hot after 30 minutes of operation... enough for wax to bubble. Now, it takes at least an hour to get hot... but this time without wax spitting out of it. So, it has cooled down some, but not enough. BTW... I still have a good stable picture.

Could my flyback simply have a minor short? Or could there be something else causing my problem?

Charlie, compare the flyback temperature to some other tube sets with similar characteristics...the heat you feel now that you have fixed the problems may be normal.

I had considered that some heat is probably normal, but this flyback eventually gets hot enough to where you cant touch it in some areas.

I do recall that the flyback in my Curtis Mathes (a CTC15 clone)gets "warm" after a good while. I had never bothered with checking the current in that one because I didn't feel it was warm enough to be evidence of a problem.

Perhaps I am worrying over this too much, but I hear so many of the guys mentioning their flybacks being cool as a cuke. :dunno:

I guess i'll just run it some more... maybe for a few hours straight... and just keep monitoring it.

---

Still Bubblin
 

Well, it turns out that the flyback is still getting hot enough to bubble... it just takes longer. Started bubbling wax after 75 minutes of operating. :(

The cathode current on the regulator tube slowly dropped all the way down to 100 microamps! That can't be normal.

RCA's always have drippy flyback cages. Their flybacks were junk from day one. I don't think it should get that hot tho to have a continual drip. Also IIRC isn't high-voltage for "roundies" supposed to be 21.5K? I think I remember that my Uncle always set the rectangular tube RCA's at 24.5K and the roundies at 21.5. It's been years tho, and so you may want to check the sams to be sure.

Sam says 23 to 25.5K on the HV.

Yeah, most of the RCA chassis I have here show drips. I have a cTC16 chassis that was doing the same thing, but it had leaky caps and stopped dripping after I changed them out.

I guess I am going to give up on this for now. Not making any headway, and tomorrow I must start getting ready to return to the ship. i had hoped to have this chassis finished before going back to work, but looks like that isn't going to happen.

I am starting to think this flyback has a short somewhere. After letting it run, I can feel around on the tire and find this one spot that gets too hot to touch. I guess that's where the short is. When it gets near time for me to come home again, I'll contact Moyer's and see if they have a replacement for it.

This set otherwise seems to play well. It's kinda hard to try examining the picture too closely because of a weak CRT and cataracts so severe that the safety glass will probably fall right off. But, from what I can see, it's got decent color, a stable picture, and tunes in stations great! A fresh picture toob will probably look really good running off this chassis... and look good sitting in a freshly refinished cabinet!

Here is the cabinet I plan to refinish and put this in. As of now, it's just a home to a bunch of crap!

Being that I now have a new flyback on it's way from Moyer's for this CTC15 chassis, I've decided it was time to start working on the Beauchamp cabinet I plan on putting it in. Although I really HATE stripping and sanding furniture, I knew this set wouldn't be presentable without the cabinet being refinished.

This project is coming together from two sets. I had two 15's... one was in a metal cabinet that I got from AK-er peverrett in Austin, and the Beauchamp set came from the old local tv shop here. Both sets had weak crt's, but the chassis in the metal set seemed the better candidate for repair. I have a rebuilt 21FBP that will go in when the time comes.

The other chassis will be used for spare parts. If anyone is needing any major 15 chassis parts, let me know. Polaraman already has the tuner, so that part is not available. Now that I think of it, Rich, weren't you needing some other 15 parts? like a convergence magnet assembly?

Here is my Beauchamp cabinet in it's beginning stages. I really hate working down in those little cracks. But, I know in the end it will all be worth it!

Charlie, do you have an extra HV cage door? Mine is long missing. I was also looking for a couple center convergence magnets but the ones I made up with popsicle sticks work alright so I'm not going to worry about that.

Bryan,

I do not have HV cage doors for either one. it appears that both of these chassis had flyback troubles, and I am assuming that the shops that originally looked at them tossed them to the side or reused them on other sets.

However, I do recall another 15 in that old tv shop. Next time I go I will take a look for you. IMS, most of the color sets I saw in that place had flybacks that went south, so that set may have a missing door as well... but I'll look for ya. :)

Flyback has arrived!
 

I was outside sanding on my cabinet earlier, and the big brown van drove up! Tell me, how many of you have a sexy long-haired brunette girl making your UPS deliveries? This girl here really redefines "brown is better". :D

Uh... okay back to the tv... so i was excited cause my new flyback arrived. Wow this baby looks like it was manufactured yesterday! Not to mention feels like it's built like a brick shithouse! The side of the Thordarson box says IMPROVED RCA REPLACEMENT. Just by the way it feels, it's got to be better!

Looks like I know what I'll be working on tonight! :yes:

Charlie, was she impressed that you were re-building a 40-year-old TV? Could be a great icebreaker for a cute girl! :naughty:

BTW, If you ever need tailights for that Duster, I have a set that I've been trying to unload on Ebay since forever!

Actually, one look at her and I completely forgot about the TV!

I think I will be looking into replacing the Duster if I can find another like it. I saw one on ebay just like mine, but it was a slant 6 instead of a 318. For the money I would have to pour into mine, I could just buy another one. I'm gonna think on it some more, but, i'll be keeping my eye open as well.

You sure that delivery gal wasn't a TV herself? :naughty: Here in San Fran these sorts of questions do come up!

Anthony

Focus rectifier
 

As I was swapping parts from one flyback to the other, I decided to put a meter across the focus rectifier to check it. According to the meter, this one is open (checking it in both directions). For the hell of it, I pulled the focus rectifier from my spare 15 chassis, and it gave me an open reading as well. Hmmm... being that these are so large, will they not check on a meter in the same manner as a modern diode?

As I recall from some time ago, seems I remember checking the focus voltage a while back and it was within specs. However, when running this chassis in a set, the picture was a little fuzzy. At the time, I had blamed the fuzziness on the 21FJP's safety glass being completely delaminated all across the face of the crt.

I am going to go ahead and re-install the old one because I do recall checking the focus voltage before and it was good.

If it turns out that i do need to replace this, what do i need to get? Sams has a listing for the original part number, but no measured current. I am going to assume that this is not something I can go grab off the shelf at the Rat Shack.

Focus update
 

I called the guy that has the old tv shop in town and gave him some numbers. He cross-ref them and found he still had some NOS focus rectifiers from way back. He pulled them off the shelf and tried checking them the same way I did, but got the same results I did... nothing.

Is there a reason for not being able to check these on a meter?

He is going to save what he has for me incase I need spares since he no longer uses them. :)

---

Hi Charlie,
Older high voltage diodes are usually made up of a string of lower voltage diodes in series to get the desired breakdown voltage. A meter usually uses about 2 volts to measure a diode which is sufficient for any type of single diode. When they're in a chain like this you need to provide enough voltage for the sum of the diodes. Using 0.7 volts each, and guessing at 5 diodes, you would need more than 3.5 volts to forward bias the focus rectifier. You can try using a 9 volt battery and a resistor sufficient to keep the current to a milliamp or so, and set the meter to DC current to check the diode.

Darryl

Looks like Andy beat me to it :)

Thanks guys... I am going to continue with the assumption that it's good. :yes:

During all of this, I did discover a 100k resistor connected to the focus coil that was way off... it was reading 16k. Hmmm... maybe this was the reason the old flyback kept getting so hot after running it for a while. :scratch2:

Flyback update
 

I got the new flyback installed today, and so far, all is looking good. :) No bad surprises when I fired it up, and it has been running a little more than an hour with hardly any heat at all. There is a slight warmth, but feels like it should be normal. Nothing compared to the heat the old flyback was putting out! Currents at the HO tube and HV regulator are all within spec and steady. Focus voltage is good, too.

Can't say much for the picture right now. The crt this thing is currently connected to is very weak and has severe cataracts. The raster fills the screen and the color is working, so that's all I can say for the picture.

As of now, this chassis still has all of the original lytics in it. I have been debating whether or not to install the new ones. I probably will.

The cabinet is ready for stain, so, i'll start on that tomorrow.

At least my flyback troubles are solved! :D

Charlie,

I still need the convergence magnets. Plus the ring with the slides that goes behind that. My set would be complete then. Have just replaced the vertical output transformer in mine. I just got outbid for a CTC 15 in maryland.

What year Duster is that? My folks had a 72 lemon yellow twister with a 318 and 3 speed combination. It had the houndstooth interior. I want to get one and recreate my parents car.

polaraman

I'll be able to fix you up with those items. :yes:

The Duster is 72. Houndstooth with a yellow exterior? Man I bet yall had to wear shades whether you were in or out of the car! :beatnik: :smoke: :beatnik: :smoke: :beatnik:

Not meaning to hijack the thread or anything...

I learned to drive on my dad's '74 Gold Duster. Had the 318. Lotsa power but no traction.

Color was "Tahitian Gold" (metallic brown, really) with the snakeskin half vinyl roof. Interior was white with horizontal earthtone stripes.

Looking back at the old ads, Plymouth made a big deal about how compact the car was. Always seemed like a bigass land yacht to me. Heaven forbid I'd ever have to parallel park it. :D

Yeah, they aren't much for traction with any V8 and standard width tires. :no: You need to have AT LEAST 70 series tires to be able to grab the pavement. I think mine had E78-14's on it when I got it. They lasted a week (and that was after rotating them at least once). :D

Still making progress here! Got all of the sanding finished on the Beauchamp cabinet and just completed staining it. Next will be the varnish. That will take forever! Varnish, sand, varnish, sand, varnish. :worried: Oh well... it will look good by the time it's all done! :yes:

In the meantime, the chassis has been running for the past five hours straight and monitoring currents and heat at the flyback. All is good there. :)

Charlie, you are gonna have to start photoshopping that Duster out of your pics! It's a scene-stealer!

My parents 1972 Duster Twister was a dealer ordered car. It was supposed to attract attention to the dealership. It was lemon twist yellow, Black vinyl top, black side stripe, houndstooth interior with black trim. All other interior components were black. 318 with a 3 speed on the floor with a bench seat. I have only seen one like it. It was a 1971 with all the same options except it was a 225 slant 6. I was tempted to buy it but it was hammered on the left quarter. It would have needed a whole new body. All the parts were there to duplicate my parents car. I am going to Big Daddy Don Garlits Mopar show tomorrow. It at his Drag Racing Museum in Ocala Florida. Yee hawwww!