Rca ctc-5h

[dtryon]

Guys,
Here is an unbelievable deal on a TESLA COIL that will do the gas test as described. It's so cheap it's hard to believe they can sell it for this amount. I have tried them and they work well. I bought 3 just in case one breaks and put it in a plastic project box to use as a piece of test equipment. here is the address: https://www.ebay.com/itm/15KV-High-V...19.m1438.l2649

Hope you guys can use this,

Dennis

[EdKozk2]

I pulled this quote from an old CTC-5 thread of Dave May in 2013. The quote is from Old TV Nut.----

" If the drives required for the red and blue guns were equal to make white, then the pattern would need to be elliptical, with the B-Y gain = 2.03/1.14 = 1.78 times the R-Y gain. (These are the ratios dividing the B-Y and R-Y axes before the chroma is modulated.) However, the red phosphor in the early tubes is weaker by about the same ratio, so equal (approximately) is correct (that is, the pattern is circular).

By a fluke of changing both the green and red phosphors in later tubes, the red gun requires less drive to make white; so there was a fix to reduce the red luminance drive; and at the same time, the yellower green sulfide phosphor means that the extra R-Y drive is still needed, to approximately compensate by making the difference between reddish and greenish colors greater. So, the matrix adjustment does not have to change, and can stay with a circular pattern when a new CRT (e.g., 21FBP22) is substituted. "

I was wondering if anyone has a schematic or an idea of which components were altered for the reduction in the red drive? I already found the contrast/ brightness fix schematic for the 12BY7a video cathode modification.
Thanks,
Ed

[Electronic M]

Given the existing mounts on your replacement tube ED it looks like you should be able to loosen the band, slide the brackets to the right position to bolt to the cabinet, tighten the band and be good...Don't know if the degauss shield can be kept, but it may not be needed in the mounting anyway.

[old_tv_nut]

Back in 2004, I used part of the mounting hardware from a CTC-7, along with some make-shift brackets, to mount a glass tube in my CTC-5. Unfortunately, all of the pics in that thread have disappeared. Of course, I saved all the CTC-5 hardware and used it later when I got a 21AX for the set.

[Tony V]

What i did on one of mine was remove the mask to get at the original mounting bolts and replaced them with longer ones. I then reused the plastic housing which slid back in place as it is only slid out about an inch and a half from the original crt position hence the longer bolts. Of course i had to take a hole saw to the side of the housing so i could hook up the anode lead. The outer magnets and hardware were removed from the mask. The good thing about this route is everything can be put back original if a good 21axp22 is found or if the old one can be rebuilt. The chassis had to be slid back an inch because two tubes were right up against the housing but this might not be an issue depending on what cabinet you have.

[EdKozk2]

Thanks for all the replies,
Thanks for posting those pictures Steve D.
I like the approach you took Tony V.
Tom, I not sure the Zenith brackets will work with the lack of space, but I'll check.
Old TV Nut I read your old thread from a few years ago, when you put a 21axp22 back into your ctc5 .
From reading everyone's suggestions, it looks like the purity magnet assembly should be removed that surrounded the old, first.
Thanks for all the help,
Ed

[old_tv_nut]

Originally Posted by EdKozk2

Thanks for all the replies,
...
From reading everyone's suggestions, it looks like the purity magnet assembly should be removed that surrounded the old, first.
...
Ed

Right - the edge magnets were totally unnecessary with the glass tube, and actually may be mechanically in the way and magnetically may make things worse.

[EdKozk2]

Originally Posted by Tony V

What i did on one of mine was remove the mask to get at the original mounting bolts and replaced them with longer ones. I then reused the plastic housing which slid back in place as it is only slid out about an inch and a half from the original crt position hence the longer bolts. Of course i had to take a hole saw to the side of the housing so i could hook up the anode lead. The outer magnets and hardware were removed from the mask. The good thing about this route is everything can be put back original if a good 21axp22 is found or if the old one can be rebuilt. The chassis had to be slid back an inch because two tubes were right up against the housing but this might not be an issue depending on what cabinet you have.

I ended up trying Tony 's approach to mounting a 21FJP22a crt in the CTC5.
Four longer bolts and cutting a hole for the HV lead.
I encountered two issues and was wondering if Tony had the same issues? One is that the deflection yoke is now 1.5 to 2 inches further back from where it used to be positioned. Tony do you remember if you made any changes to reset the deflection yoke?
The other is arcing that looks like lightning across the sky between the inner old plastic cover and the dag coated crt. In my case I have grounded inside and outside of the plastic cover. I also grounded the crt's dag. The charge builds up, discharges then does it again. How large is the diameter of the hole you drilled for the HV anode lead? If I enlarge the hole I already have , I'll start cutting into the plastic cover's ribbing.
A few pictures of the first tests tonight. I think all three color guns are working. When I tested this crt a few months ago the green tested the weakest.
If anyone has encountered the same issues, please feel free to chime in.
Thank ,
Ed

[ohohyodafarted]

I would try un-grounding the dag on the crt and let the grounded dag on the outside of the plastic shroud act as the HV smoothing capacitor.

[EdKozk2]

Originally Posted by ohohyodafarted

I would try un-grounding the dag on the crt and let the grounded dag on the outside of the plastic shroud act as the HV smoothing capacitor.

Thanks Bob, your suggestion worked. A big improvement.
Ed

[EdKozk2]

I ended up removing the inner 1/2 inch circular deflection coil stop. Had to cut it flush to the inside surface. This allowed enough space for the deflection coil to slide through and seat all the way against the crt neck. I drilled a hole 3-7/8 inches inward on each side from the covers' rear. The holes were kept along the same horizontal plan as the existing slots for yoke adjustment. I cut some 1/4 inch thick plastic spacers to fill the gap between inside housing and deflection coil clamp bracket. The trickiest part was placing a washer and nut on the inside end of each adjusting screw. I didn't want to drop them in the yoke or crt housing.
Two of the pictures below show the longer bolts I installed to extend the plastic housing rearward about 2 inches. I used 1/4 inch thick plastic sleeves as spacers over the four 1/4-20 hex head bolts. The upper two bolts are 4 1/2 inches long and the lower two are 4 inches long. The shorter bottom are to leave more clearance for the chassis.
These modifications made it possible to get the convergence coil assembly in the correct location on the crt neck.
I have yet to deal with purity and degaussing the screen, it's really bad. I also have to get the chroma circuits going yet. There seems to be no color, I'll try a new crystal before I get carried away.
Ed

[UberVacTuber]

Originally Posted by EdKozk2

The other is arcing that looks like lightning across the sky between the inner old plastic cover and the dag coated crt. In my case I have grounded inside and outside of the plastic cover. I also grounded the crt's dag. The charge builds up, discharges then does it again.

This is the section of the post I am referring to. It was mentioned to unground the CRT dag and let the boot "act as the HV smoothing capacitor". This was reported to correct the issue, but it seemed backwards, hence why I asked about it.

[EdKozk2]

Originally Posted by Tony V

The chassis had to be slid back an inch because two tubes were right up against the housing but this might not be an issue depending on what cabinet you have.

I had the same issue with two tubes hitting the plastic crt housing. One tube only required cutting down the height of the tube metal tube shield. With the other tube I made a right angle extension socket.I used some 3/64 inch brass tubing bent at 90 degrees to support the socket. The chassis now slides into the cabinet where the chassis bolts line up. It's a very tight fit.
Ed

[EdKozk2]

A few pictures after I adjusted the chroma board slugs to try and duplicate NTSB color bars. I found the 3.58 MHz oscillator to be out of tune, which was causing barber poling. I was able to adjust the convergence and purity a little better following the procedure in Riders' for RCA 22-149 through 22-169.
Ed

[Tony V]

Excellent job so far Ed! You took the adaptation to another level than what i did and after seeing your results, i will be making a few changes on mine. This thread is going to help others who are in the same boat as we were because as far as i know there isn't much out there on this problem as far as the CTC 5 goes. I'm looking forward to seeing the end result of your restoration.