first tube set - Videokarma.org TV - Video

mustang84 · #1 10-08-2008, 04:44 PM

i am new to this.i am the owner of the ctc25 rca.this is my first project of this type.ron said i should ask and learn from the guys here in this site. it currently has a picture.full screen and it has sound until the agc and sync tube warms up.if that tube is removed from the socket there is sound and a faint image on screen.i really like this set and hope to restore it to its former glory.when i got this from my uncle.it was a dead set.a wire was found in the power supply to be corroded.set was sent to the basement in the early 90s because of a slight weaving that drove people crazy.it had a new crt installed in 1990.cabinet is very nice and it is a good looking piece to display.i want to repair it and learn along the way.thank you for your help.

drh4683 · #2 10-08-2008, 05:12 PM

Hello+Welcome to the forum,

Is the picture still weaving with no other picture problems, or does it have weaving with purple/green tinting in the picture? Thats a sign of a leaky filter cap, or a bad degaussing thermistor respectively.
Just out of curiosity, what kind of tube tester do you use? Try to stay away from those lower end testers that only test cathode emission. It is very important that the tester be able to test for "grid leakage" or "grid emission" in TV work. both are the same thing. Do you have a schematic of this TV available? Id start checking voltages at the sync/agc tube and see whats up in that area first. I assume the AGC control doesn't help things. Does the set work like this regardless if an antenna or station is tuned in?

freakaftr8 · #3 10-08-2008, 05:17 PM

You said weaving. Kind of like a crawl in the picture? I would say that you have an issue with your set needing new power supply capacitors. These are the big aluminum can looking caps that stand up off the chassis. Imagine a red bull can stripped of it's color. These are what you are looking for. Be careful, the caps hold a nasty voltage for a long time. Your crawl is most likely those caps have gone south. You can get substtute individual caps for you set. Read up about how to recap a chassis.

As for your AGC/ blanking issue, sounds like a tube. check all your IF and bandpass, and AGC tubes. But remember this could be a faulty cap as well. Running your set on bad caps could and will most likely damage something soon.

The values on these caps are written on the cans. These cans usually have 2, 3, 4 or more caps inside.

mustang84 · #4 10-08-2008, 09:06 PM

cant tell if its weaving.all tubes checked out in another set that my buddy has.his is a ctc16 i think. agc control has no effect.you can see the color and the images moving,they are just like an x ray.service line is very bright. i think crt is excellent.it checked really well on rons tester.he got it to power up and cleaned up some repairs.i am really excited about it now and want to learn.he said to get online and ask questions.nice man,very interesting and modest.gives good advice if you ask.i need to learn basics.where do i start?how do you check a resistor,capacitor,diode,etc?how do you read a schematic?i hope to not drive anyone insane.

***Eric H*** · #5 10-08-2008, 10:00 PM

If you can see the colors but they look like an "X-Ray" it sounds like possibly you have the Chroma but not the Luminance?

mustang84 · #6 10-09-2008, 10:42 AM

yes ,it has color.when you turn the color off you get blank raster.rememeber,this is when the 6ka8 is out of its socket.could those caps (cans) cause this problem?i noticed a slight vertical issue also.i think it may have been attempted to be fixed long ago.a barrel type capacitor was found unsoldered under a can.looks like someone tryed to fix the weave?it fell out when we pulled the chassis.my friend said it was common for techs to "try" a part before soldering it in.maybe this caused the problem?

kx250rider · #7 10-09-2008, 12:33 PM

The weave is almost definitely a bad electrolytic can. Seen it 1000 times in the old RCAs. Probably an 80 uF @ 450 volt section. You can test by taking a tubular 80@450 cap and temporarily clipping it in place across the original, with the (-) connected to chassis ground and the (+) to the suspected can section terminal. That's not a permanent repair though, as you need to remove the old section from the circuit in case it decides to short later, or if it adds value to the new capacitor, causing a tax on the power supply.

Charles

mustang84 · #8 10-09-2008, 08:18 PM

really cant see the "weave" as i want to get as picture on this first.old cap was installed with the - on the can and the + was on the ground.maybe that was problem?i will recap this after i see video.

sampson159 · #9 10-09-2008, 08:35 PM

hey randy! glad you took note of that cap, i missed that.that could have taken something out in the if circuit.are you making any progress?these guys in this forum are by far and away,the best and nicest folks alive.it wont be long before your set is up and running.call me when you get it going.we will watch a game on it.i ll bring food and tubes!!!