Rca? - Videokarma.org TV - Video

DaveWM · #1 03-09-2011, 02:40 PM

http://orlando.craigslist.org/atq/2220903462.html

Picking this up today, free so I guess is better me than the scrappers

radiotvnut · #2 03-09-2011, 03:02 PM

That looks like a delta gun CTC8x or 9x chassis from the late '70's. It could also be an inline gun CTC10x chassis from the early '80's, since the design didn't change much during the late '70's-early '80's. I don't think it's old enoough to have the upright CTC68 chassis in it.

At any rate, if the CRT is good, it should make a nice picture.

DaveWM · #3 03-09-2011, 03:06 PM

I am mainly just getting it for parts, I really don't have room for it, but I know its fate if it goes to the street...

I am hoping for a decent 25v delta gun.

radiotvnut · #4 03-09-2011, 04:45 PM

Don't expect too much out of that tube, unless it's been replaced sometime in the sets life. Those "late" delta gun RCA tubes from '77-'80 didn't hold up that well. I saw plenty of these sets, when they were younger, with weak and/or shorted CRT's. And, rejuvenation didn't always help. At present, I have a 19" RCA delta gun colortrak from '79 that got a new CRT when it was less than a year old.

DaveWM · #5 03-09-2011, 05:18 PM

here it is. The CRT is a delta gun, the CTC number is rubbed off, all the guns tested ok, but the Blue setting had a much different cutoff, and it did not track well on that gun. I dont know that I want to mess with this.

there is a fuse and its ok, the degausser works, but thats it. I can hear a rapid ticking coming from the side where the fly is, beside that and the dial light coming on I get no sign of life.

oh the CRT is a 25vCZP22

sampson159 · #6 03-09-2011, 06:33 PM

late 70s colotrak?decent sets bit not as good as the earlier xl100s and the fold down chassis colortraks.seems crts went south on these sets.they will take a jolt periodically though.there is a diode in the power supply i can remember that was a problem.same characteristics of your set.good luck with this and i have a good crt if you need it

DaveWM · #7 03-09-2011, 06:35 PM

well for fun I checked the HOT, seems ok (.4v diode mode BC,BE nothign CE.

I will look around for that diode

DaveWM · #8 03-09-2011, 06:48 PM

from what I can tell the AC interlock connects to a board with a fuse, thru the degausser, then a bridge rectifier, I get lost after that. But there is this odd looking can, looks like a small can cap, about 3/4 wided and tall, has 3 thick metal legs. I dont think its a cap, just a guess but some kind of relay in a can?

Gunslinger · #9 03-09-2011, 08:01 PM

what you need to do is use a variac and isolation transformer on that set. Pull the regulator board out. Jump out the coil (forget the number of it; it separates reegulated from non-regulated voltages). See if it runs. You have to put 27 vdc from an external supply to start the horizontal.

There is a electrlytic capacitor in the 27v supply that used to go bad. Also, a 680k resistor opens at the regulated coil leads. I made a living repairing those sets. RCA called that chassis the extended life chassis. I called them "no life sets". They did have a great picture.

DaveWM · #10 03-09-2011, 08:23 PM

well that was too easy. the only thing I did was pull the HOT and re-seat.

Also pulled what I think is was the sweep board (just to check some transistors).

decided to put it all back in to look for voltages, instantly got audio noise, (it wad dead silent before),

Bingo

DaveWM · #11 03-09-2011, 08:30 PM

That was so easy I am going to see if the orig owner wants it back.

DaveWM · #12 03-09-2011, 08:51 PM

there is a little bit of noise in the pic, I think its from the conrast control (touch it and the noise comes and goes) so I will go thru the pots and give them a quick cleaning. I was really kind of hoping this one would not work so I could just scrap it for parts. But the convergence is PERFECT, the color bars are PERFECT, I mean better than anything I own. Oy Vey.

Gunslinger · #13 03-09-2011, 09:17 PM

the sweep board you mentioned...if it's a board 2inches by 3 or 4 inches mounted on the right side of the aluminum wing, that is the regulator board. Part # 142709

DaveWM · #14 03-09-2011, 09:41 PM

the board I pulled is in the 4th pic on my chassis shot, 3rd board on the right, just above the horz adj (long red pot shaft).

a couple other thins, the horz hold is super critical, it will flop one way then the other. You can get a stable lock, but it only has a couple degrees of rotation at best to hit the right spot (which is in the aprox middle).

The vert lock is strong so I doubt its a problem with the sync sepearater, I am thinking the AFC circuit in the horz. Maybe some drifted resistors or dual diode (I assume this is how its horz AFC works if its like tube sets), perhaps even a weak cap in the feed back pulse, just guessing. I am going to let it run for a while and see how it goes.

This thing would be a "green" tv by todays standards, its barely pulling 1 amp, my tube sets are amp hogs by comparison.

Gunslinger · #15 03-09-2011, 09:49 PM

that is the horizontal drive board. Uses a count down circuit. Those adjustments were rock steady. Scope the 27 volt line for hum. Also, if you have a marginal regulator, it will fall out of horiz sync due to the horiz disable ckt. I may still have the training manual. Will give a look see tomorrow.