CTC-15 restoration

[mstaton]

I had a set that did a similar thing. If I turned the contrast one direction it looked like this(see thread: http://www.videokarma.org/showthread.php?t=252862) but id I turned it the other way, I got a weak but full raster. ALL the canned electrolytics were dry. Good HV and B+, screen volts OK.

[6GH8cowboy]

The quad E-can at the end has been replaced (bad seal, dripped, dried out) others are OK. I have subbed to make sure any way. Replaced the .1 on the agc line to the IF strip and the video from the detector looks more stable on the scope. Looks good going into the 12BY7, bad coming out I may just shotgun all the related components and reflow all the joints. I hate black magic fixes like that, I would prefer to know what exactly the fault is, but this is getting time consuming for this one problem alone and I have not yet seen what other things will have to be addressed.

[DaveWM]

screen resistor/contrast pot/service switch for trouble with the Video out.

I have also replaced the grid coupling cap on the video, but if you are good at the grid then that should not be a problem, unless is just a bit leaky. That "could" account for the low plate voltage. I know you did voltage checks but don't remember the results.

I am assuming the 50uf cap on the contrast control is not shorted.

[6GH8cowboy]

Brief raster on the left dark screen with close focus. Drum roll please


The focus rectifier! Likely shorted. After seeing decent signal on the scope (after soldering all the parts in the area and grounds I still had the strange symptom yet wave forms and DC on the CRT grids and cathode looked good. The last thing to ponder "the focus grid. The voltage was a bit rich in AC content so a rectifier change was in order. I also discovered the previous person had a 100 ohm resistor in place of the 1 meg in series with the focus lead also.

I now have a picture in near focus but a unresponsive focus control. I can now view a picture and see there is much to do like AGC and sync issues. Vertical gain next, then color. The CRT is looking decent but the cap is scary loose and I've had to re-flow the solder in some of the pins.

Any suggestions to secure the base to keep it from moving short of JB weld? I don't want wires to break from movement

Progress is being made

[DaveWM]

if there is still some of the brown glue left but just not stuck, I have had luck with a product called "flex zap" you can get it at model shops. Its a kind of CA glue but has some give to it so as not to shock break in heat cycles.

If the focus is not responding, 1st check the focus voltage and make sure you are getting an adjustment of at least 500v. I use a simpson 260 in the 5kv mode.

does the focus coil look cooked?

[6GH8cowboy]

I'll look for those two parts in particular. The cathode cap is on the change list for sure. I'll also be checking for about a 150 ohm path between convergence pins 1 and 2. I'm going to verify the B Boost voltage but I suspect it's close as the screen for each gun is pretty perky.

Parts changed

Pictures added

Still suffering a lack of vertical deflection.

I now have a remote unit but I believe its for another RCA set but I think it could work. A freq counter loosely coupled shows 35 to 50 khz depending which button is pressed. That seems a bit broad to me and there is only one adjustment. I was expecting there to be only 1.5 kc apart for each function.

[6GH8cowboy]

This set has a CPT10-A reciever and the handheld does not match the Sams schematic. The diagram shows a different component layout and has trimmer-caps to tweak each function.

The handheld I have has only one adjustment and the measured freqs dont match up even close to several functions. Some do. The only ID on the inside on the PCB indicates E-143365-1 RCA-5.

The only trimmer was soldered so it was replaced. The channel freq is right on and I'm back to the original issue. I get the idea this is not the remote for this chassis or I'm going to have to play capacitor roulette for each function.

Is this the wrong one? Is there a practical solution.

[Charlie]

Did you change the lytic on the sweep board? I think it's 50uf... can't tell in your photo if that's a new sprague or and old one in the cardboard sleeve. That capacitor usually opens up the picture if adjustments do not.

Other than your picture not opening all the way, it looks really nice. I'm jealous that your Vislanda is a remote set. Mine is not.

[6GH8cowboy]

That (cathode) cap has been replaced and checked and subd.
At this point all parts have been replaced with the exception of the yoke and V. transformer. The path through the convergence is good at about 130 ohms. I have not replaced the VDR. B- boost checks about 1100 volts with a triplet meter.

Wish I could say this ones mine. It belongs to a local VK collector, I'm helping him out with the varied technical issues.

This one (CTC-15) is a beast as far as this vertical issue goes. This is a high hours set and had a number of problems you'd expect to sometimes find, but all at the same time. It also has had a lot of previous attempted repairs.

Odd thing is I recently had a CTC-16 that fought for Vertical as well. It just barely makes it and I'm taking a wait and see, figuring if it gets worse, it'll be easier to find.

[miniman82]

Hard to tell if it's a linearity problem or height problem, can you post a pic with crosshatch pattern? If it's not lin, is the correct voltage reaching the vert out tube plate? If not, I'd replace the vert out trans or sub a yoke to see if either of those solves the problem.

[6GH8cowboy]

This is the best I can get at the moment. The top tends to crush. I can get linearity with a smaller sweep but if I go for max the bottom streches and the top flatens out. I don.t think the DY is bad as there is not a whacked geometry. The VOTrans is quiet and cool. With the service switch on there is about 396 volts on the plate of the output tube section, Grid 0v and cathode 85v. so its pulling current and the plate volts seem healthy. I suppose there could be a shorted turn but I would expect a more visual symptom.

Now since the last chassis removal the brightness control has stopped working. Wish I had a jig and more room. argh...

[mstaton]

Does the vertical centering pot work? I has 2 go bad in my 2 16's and cause strange problems. Might just be a broken wire on the brightness pot. my 9 has extreme hours on it and all the wires want to just fall off when you look at them wrong. Looks great otherwise.

[6GH8cowboy]

That white cap is the buffer on the plate. A .001 2kv cap. I replaced with a 1600v unit and later put this NOS piece in to see if it made a difference. The centering control has been replaced by a previous person, measures 12 ohms and adjusts smoth on the screen. It looks to be good and both secondaries of the VOT to the centering pot and yoke as well.

[DaveWM]

there is a gold banded resistorcircuit of the vert multvibrator, 24k R508 and check the 2.7 meg R515. The 24k can make a big diff in vert sweep

[Charlie]

I can see a white ceramic tubular capacitor under the deflection board. Don't know what it's for, but I bet it needs to be replaced. Those are never good.