RCA CTC4: the barberized Seville

[miniman82]

What the tester says means squat when it comes to HV rectifiers, unless an open or short is indicated. They simply don't test at a high enough voltage to get reliable results.

[mstaton]

That is so true. I struggled with my 9 with strange HV issues. I could hardly adjust the HV up or down. the regulator and rectifier tested good. I replaced both with NOS and now works great. Tube testers cant always find problems with HV tubes like miniman said.

[Electronic M]

Been back on it for a bit, and here is what has been happening.

After my last post I scrounged a replacement slug from the width coil of my 9-T-246 that seems to be the best thing I have on hand. pictures below.



The HV was (and is still) at 20 KV. The dead IF intermitant that was bugging me devolved into a completely dead IF.
I then got too busy to touch the thing for several weeks.

I got back to it over the week end.

The IF has gone back to intermitantly not working from being dead merely by sitting around. I'm fairly sure this set will need an alignment at some point to work right as color sound and monochrome don't seem to lineup as well as they should.

I did not feel like messing with the IF and HV issues, and instead began tweaking the color circuits. It was hard at first because I did not have a nonmetalic alignment screw driver that was long and slender enough for the dual-core transformer let alone two to tweak both slugs at once. So I went to Radio Shack to see if they had those tools available, and let me tell you that I felt like I was in a grocery store that doesn't stock bread when I was told that those tools haven't been on the shelves for a long time! I ended up making my own alignment tools from some used up mechanical pencils I had laying around from the previous quarter of college which were waiting to be thrown out (good thing I didn't get to that). Shown below are my home made alignment tools.




I have the color adjustments a good deal better than before, but there is still much room for improvement.




Think I'll go at it some more tomorrow......I should really get to bed now.

[zenithfan1]

Hey Tom, this thing is really coming along. It looks good, I saw it in person before you got it. How's it going now? Have you had the time to keep working on it? Good job!

[Electronic M]

A heck of a lot has transpired since my last post in this thread: College finals, a move from an apartment into a sizable house, work on the CTC-4, and I have on going remodeling(my folks are counting on my skills), emptying out of my families HUGE storage unit and work to get my stuff set up and arranged(which is tough to do considering that the other two things eat up a comparable amount of time to college).

I have not mannaged to work on the CTC-4 since the move, but before that I was working to remove the rust from the tuner shields and making decent progress(I lost some screws though ). It was coming along nicely and almost done, but it is starting to rerust so I may just spray paint the offending surfaces silver and say 'good enough'. Part of me wants to use lacquer, but I don't have a great budget and want to save where I can.

About all the actual 'work' I've done on any of my equipment was setting up my stereo/video system (which not only is unfinished, but already needs to be mostly redone because of new finds changing the way I want to do things), fixing an Atwater Kent model 40 for (and with) a friend, and starting to spray paint a rusty TV cart that is a factory accessory for a Zenith set I like.

As the set sits the alignment is lousy, that damn IF intermittent persists, and I feel like, given the behavior of the color demods tinting the raster(or was it selective weak colors...crap I'm starting to forget things!), that there are probably off tolerance resistors that I need to look for and replace before taking Nick up on his generous offer to align it for me. Once it is aligned that may be it for the electronic end of the restoration unless I buy some fresh pots for the convergence board. I really doubt that I can preform the kind of cabinet restoration this set needs(I want to teach myself refinishing etc. later this summer if I can but don't know if I will have time), but I don't know if I will be able afford some of the repro parts I need for this set this year let alone pay for someone to restore the cabinet.

I've got a lot of projects calling for my services at present, but one of these days I'll get back on it.

[miniman82]

Tom,


There is a guy right there in Milwaukee that can handle the cabinet for you, he did my CT-100 for me and it turned out better than new. Didn't charge too much either. Hit up Bob Galanter for his contact details, guy's name is Dennis.

[Electronic M]

I'm back on the chassis after only a brief ~8 year break. lotta water under the bridge since then. I got my EE degree and a job. When I got this Seville way back when I had around 10 monochrome TVs, 2 tube rectangular color sets, and 2 CTC15 clones....I now own every RCA color before the CTC-7 (2 each CTC4 and 5), Philcos first production color and Motorolas third (which even combined together are rarer than any RCA). And own or have serviced almost every RCA roundy from CT-100 to CTC-20 except the 7 and 10-12....

This resto originally went on hold due to a move and the sets apparent need for an alignment....in the mean time I have acquired sweep alignment equipment a good 21AXP22 to install, some cabinet restoration skills, a replacement CTC4 Havilland bottom board to replace the bowed one in my Seville and even a complete CTC4 director in better condition than this Seville....when I stopped working on the Seville chassis it had the tuner bracketing and shields disassembled for cleaning and rust removal (it all rerusted since then), a number of kludgy parallel caps and lousy ancient 70s NOS lytics from Chester electronics that were slightly leaky when acquired but better than the originals I also had forgotten to solder some of the AGC caps I changed. ...I also had a mishap where I stepped on the selenium rectifier and bent it to heck....
So why am I picking this basket case up? Well I was trying to get the picture to look GOOD on my CTC4 director and was leaning towards doing an alignment on it, but decided to practice on my worse Seville chassis first so if I screw up there's nothing to loose... Also I have all the extension cables stiting out to use the director as a test jig and the Seville chassis has been sitting out for almost a decade so it couldn't be easier to pick it up and start on it. So I replaced the seleniums, the percentage of lousy caps I used last time, changed the junk 2nd IF tube socket, painted the tuner brackets and IF shield an automotive gray that looks better than rust and it lived again and ran as well as it did before if not marginally better.
Before trying an alignment I went through all the resistors in the IF changing any off tolerance and that helped, then I went through the luminance channel and AGC/sync sep resistors and that really helped....color sync and demodulation was still a bit wonky though so I did the resistors there too...now it looks like I may be able to call it done soon. The 2 issues I have left are the fine tuning needing to be at max to have a good picture (I'm going to adjust the channel osc slugs) and I need to check and address the low HV issue I had years ago.
Once I get it working I'm probably going to put it in the director till I can get the director chassis as good or better. The Seville cabinet needs a lot of work and I need either a new HV cable insert for the shroud or to fix the snapped off CRT contact spring on the old one (the one in the director was broken and arcing when I got it and I swapped the Seville one into the director.
I don't want to work on the directors original chassis until I can track down 5 more good 6AZ8s and a 6AG7... The 9 pin sockets especially the IF are delicate and I only have 1 correct good spare left. If someone has those tubes and wants to sell them I'd be grateful...

[old_tv_nut]

Onward!

[JohnCT]

Originally Posted by Electronic M

I got my EE degree and a job.

Congratulations sir!

John

[Electronic M]

Originally Posted by JohnCT

Congratulations sir!

John

Thanks.


Last night I checked the HV and it is measuring a steady 25KV.

I just need to go after the tuner, stick this in the director cabinet and converge it...the convergence yoke is the only cable I don't have the fittings to make an extension for. My solution was to leave the one in the director cabinet unplugged and grab the yoke from the Seville to act as a dummy load for the chassis. The convergence yoke plug is essentially a 6-pin version of the battery connector on a tube Zenith transoceanic...I have a 5 pin cable and socket off an old Baldwin organ, but no 6-pin connector.

When I do get the Seville cabinet done and ready for 21AXP I'm going to need to do something about the pictured cable. There used to be a contract spring (curved piece of flat spring steel) coming from the center of the bullseye that broke off and has been lost... I'm considering trying to solder a flashlight spring on and see if that works.

[Electronic M]

From the kludge department:

[Electronic M]

Friday night I got the VHF tuner dialed in had to adjust the slugs for each channel plus the hidden master slug for CH13 and a coarse osc adjust trimmer. The procedure I followed was to start at 13 making the coarse adjustments to give it enough range and work my way down the channels.
I started. By going the other way and made things worse before making them better.
All but one channel has good sound color and monochrome alignment on the fine tuning and all channels optimum fine tuning is in range of the fine tuning control...I would have liked to line up the osc so each channel is the same position on the fine tuning but that isn't easy especially with my body position effecting reception and affecting it differently on different channels...But it is good enough that it should work well on any VHF channel I'm ever going to pipe in to it and that's all that matters to me.

Last night I took a crack at making the UHF tuner work....it will tune in everything from 13-35 on one position of the UHF tuner and nothing elsewhere. Since I don't use a UHF modulator normally and only wanted to make the UHF channel indicator match the tuner position I decided to leave it alone.

I also removed the safety glass and trim and cleaned the rotten rubber gasket gunk off the bezel with isopropanol and off the glass with goof off. I then polished the bottom of the brass trim with brasso and steel wool and sprayed lacquer on it. I reassembled it upside down to hide some small dents and and minor color difference on the bottom. I may go back and hit a couple spots on the side which I notice more now that it is back together. I'll post some pics of the cleaned up trim/safety glass later.

All I need to do now is convergence and reassembly.
Once that's done I'll go back to my Moto 21CT2B and order the tubes the other CTC4 chassis needs and some slip plate to replace the silver foil that has peeled off it's CRT shroud.

That all has to wait for the folks to release me from work on the enclosure for our covid19 anti-starvation garden...

[Electronic M]

A week ago Sunday I assembled it and tried to adjust the dynamic convergence...It seems like only the blue H amplitude control behaves as it should (vertical seems to be okay).
I decided that I'm not going to sort about the dynamic convergence being poor. I ran it through the whole Wizard of OZ and at the end installed the back it was then that the only 2 original capacitors (the B+ doubler caps) decided to fail so the next morning I changed them and then gave it another OZ run through (this time with a little less pointless letter/pillar boxing from my settings challenged Blu-ray player. The next couple of days I gave it some run time too. Last time I ran it green seemed too strong in the grey scale.... I'm eventually going to check the green video tube as I changed its B+ resistor to match the red tube and sams (it matches the RCA issued schematic) to try and improve green demodulation response.

At some point hopefully soon I'm to try to spruce up the Seville cabinet....After t tubes I need for the director chassis arrive I'll try to make the director chassis work better than the Seville chassis does then I'll pull the Seville chassis out of the director and try to have both my CTC4s working....

[ohohyodafarted]

If your convergence controls are non-responsive, you may have to rebuild your convergence board. Those 100 ohm pots are notorious for wearing out. My Hallicrafter CTC4 clone that problem and after rebuilding everything it worked perfect. AS I recall there are 6 100ohm dual concentric pots. The carbon paths wear out.

[Electronic M]

Yeah I'll probably be looking into that after this covid mess is over.

A couple of months ago I bought a fixed resistor kit that I pulled from for the Seville chassis and somehow up until yesterday I thought they were 2W parts...I double checked last night and realized they are 1W so I'm going to have to go back over the Seville and ID every 2W I changed and replace those with proper 2W parts.