Rca Ctc9a/horiz Snaking And Blooming - Videokarma.org TV - Video

chipper · #1 02-27-2008, 11:02 PM

OK: This is chip again, just when I thought I had all my convergence problems taken care of, this happen last night. I have checked just about all my HV tubes ,V12,13,14,22,23. V-15 (1V2) V16 (6BK4) I do not have setting for on my tube tester chart, and need those settings to test. Some one on another sight said to ck the crt, it might be gaseous, so I connected the original RCA colorama crt and still have the same problem. The blooming only happens when you turn the brightness up to the normal setting, which is about halfway.

radio63 · #2 02-27-2008, 11:53 PM

Checking the HV and sweep tubes on a tube checker is not a very good indicator of their true condition. They might test OK on the checker but not function under full voltage in the circuit. The best test is to substitute each tube, one at a time, looking for any changes in your problem with a blooming pix. Make sure you don't touch any high voltage points that could retain a charge when swapping out tubes. If the tubes are not the problem, you may have circuit problems in the regulator circuit or HV related circuits.

Gilbert

freakaftr8 · #3 02-28-2008, 11:03 AM

You should also check the surge supressor in the power supply, (it's the ceramic disc) with the 2 leads. I have had these fail causing the symptoms you are having as well.

bgadow · #4 02-28-2008, 12:45 PM

Snaking? That is usually a bad filter cap. Can cause other weird problems. Feel the cans after the set has been on for a little while (maybe 10 minutes) and see if any are warm to the touch.

chipper · #5 02-28-2008, 12:49 PM

OK: I have ordered replacement tubes, and will see if that takes care of the problem, But when you get int replacement of resistors and ceramic disc's that a little out if my line, I have done a few recaps on sets and have been very successful, but would have to send the chassis out for critical repairs.

chipper · #6 02-28-2008, 02:32 PM

Quote:

Originally Posted by bgadow

Snaking? That is usually a bad filter cap. Can cause other weird problems. Feel the cans after the set has been on for a little while (maybe 10 minutes) and see if any are warm to the touch.

OK Bryan: C2 Gets very warm.(160/250-50/450-50/50 caps). thanks chipper

freakaftr8 · #7 02-28-2008, 03:29 PM

Sounds like a direct cap short to me! Caps should not get any wartmer that usually the room temperature inside the chassis.

julianburke · #8 02-28-2008, 05:20 PM

Cap short? NO! If a cap shorts, it will take a B+ fuse. If a filter opens, you will get a "crawl" in the picture. A filter that opens will not get warm-only when it starts to have leakage. (starting to short) Also a weak HV rectifier (3A3) will cause excessive blooming. Julian

chipper · #9 02-28-2008, 05:34 PM

OK: Is a crawl some what like a snake starting from the bottom to the top (very slow), And C-2 is much much warmer then the inside of the cabinet and C-1/C-3. If I tap lightly on the top of the cap I get a vibration type signal on the screen, which does not happen if I tap on C-1 or 2. I'm waithing on some replacement tubes and will go ahead and change those caps and see what happens. chip

blue_lateral · #10 02-28-2008, 05:52 PM

Check the voltages on the LOW VOLTAGE power supply first. I suspect you may have a cap or diode problem there. On the schematic, it should start out at 395? then drop to 270 or so. Use the actual values on your schematic. Check voltages all the way down the voltage divider chain, comparing to the schematic. Also check for ripple (meter on AC scale).

My gut feeling is one of the voltage doubler caps is open. Let us know what you find.

John

chipper · #11 02-29-2008, 01:28 PM

OK: From T1 looking at the schematic the first source voltage is 385v the second is 270v and the third is 140v, but the voltage range on my meter does not go over 250 and when I try my digital meter I do not get any readings on voltage settings. I must be testing at the wrong points.

oldtvman · #12 02-29-2008, 04:35 PM

Quote:

Originally Posted by bgadow

Snaking? That is usually a bad filter cap. Can cause other weird problems. Feel the cans after the set has been on for a little while (maybe 10 minutes) and see if any are warm to the touch.

I agree it is probably a leaky filter cap. I can't tell you how many times I watched techs chase their tails on repair jobs, when sometimes all they had to do is go back to the basics. Always make sure your power supplies are up to snuff, and you don't have any leaky filter caps.

chipper · #13 02-29-2008, 06:06 PM

YES: Most of the caps have been replaced, especially in the vertical circuits, But the electrolytic's have not. I have had the set running for about 3 months, until this happened. It was in storage for about 10 years.

chipper · #14 03-14-2008, 11:12 AM

OK: I replaced the hv tubes and c-2, and still have the same problem, also after removing the new speaker from set too fix the purity problem, I was haveing. Do you think I magnatized the chassis by touching it when removing the speaker. thanks chip

blue_lateral · #15 03-14-2008, 12:46 PM

I still vote for a voltage doubler cap. Got any pics of what it is actually doing?

P.S. Checking the low-voltage power supply is job 1. You are going to have to find a meter that works. Don't worry too much about speakers or what is or isnt magnetized....yet. You can deal with that after this problem is fixed.

John