My Brand New CTC-7! - Page 13 - Videokarma.org TV - Video

ChrisW6ATV · #1 08-21-2015, 01:26 AM

Swizzy-

Look up "line bucking transformer" or similar. If I remember right, it is a setup where you use something like a 6-volt, 4-amp output (in this case) transformer in a wiring setup where the six volts gets subtracted from the input (122 volts in your case). Such a transformer should cost a lot less than a Variac, for ongoing use of your set.

SwizzyMan · #2 08-21-2015, 05:44 AM

Hmm a bucking transformer seems like a handful but I might give it a shot. But it says that it will lower the voltage from 120 to 110v isn't that too low?

MRX37 · #3 08-21-2015, 09:14 AM

You could also add a PC cooling fan, maybe attach it to a part of the chassis that outputs ~6 volts DC. that would run the fan at half speed and keep it nice and quiet, and keep the TV running nice and cool.

roundscreen · #4 08-21-2015, 07:27 PM

Electronic m I am sorry for the poor choice of words to get my point across.

SwizzyMan · #5 08-21-2015, 07:32 PM

Hey Roundscreen would it be OK if I ran the set just for about an hour right now?

roundscreen · #6 08-21-2015, 08:14 PM

You have been running your set to repair it. So I think it should be ok. What I do when working on a set is put my hand on the fly back tire to feel how warm it is getting. If it feels warmer than the power transformer, Shut the set down. If you do this make sure you discharge the hi voltage first. You have had to discharge the hi voltage before to remove the chassis, But still be careful.

SwizzyMan · #7 08-21-2015, 08:21 PM

Alright will do. One thing I've noticed that my horizontal hold is very bad when I first turn the set on but then 5 minutes later it gets stable. What is going on?

SwizzyMan · #8 08-21-2015, 08:22 PM

What about the ampereage? That one runs at 3 amps is that ok?

SwizzyMan · #9 08-21-2015, 10:13 PM

Quote:

Originally Posted by SwizzyMan

What about the ampereage? That one runs at 3 amps is that ok?

Back to my previous question... Is 3 amps ok in the transformer I will use for bucking?

old_coot88 · #10 08-22-2015, 10:58 AM

Yikes! I didn't notice the xfmr you were looking at is only rated at 3 amps. No, that would give it very little 'headroom' since the TV draws pretty close to 3 amps.
You may not need bucking at all. First measure the heater voltage as Roundsreen suggested.

SwizzyMan · #11 08-22-2015, 10:58 AM

Well against my better judgement on money I just decided to get a variac. It is safer and a lot less complicated. Horizontal hold for the first 10 minutes is still a problem. But at least I am being nice to the set and giving it proper line voltage. Going to refinish the cabinet tomorrow.

roundscreen · #12 08-21-2015, 08:40 PM

Quote:

Originally Posted by SwizzyMan

Alright will do. One thing I've noticed that my horizontal hold is very bad when I first turn the set on but then 5 minutes later it gets stable. What is going on?

Replace the 6cg7 and see if that helps

SwizzyMan · #13 08-21-2015, 08:44 PM

Replaced it twice once with another RCA used one I had that didn't work so then I put a Nos sylvania tube in and still no luck. Horizontal has been a big problem since the beginning. Is the high line voltage causing this?

roundscreen · #14 08-21-2015, 09:01 PM

The best I can tell you is I have never seen high line voltage cause a drift problem.
Take your volt meter and measure the heater voltage. Is it 6 volts?

SwizzyMan · #15 08-21-2015, 09:07 PM

I have no idea how to measure vacuum tube voltages... Can I use my DMM?