Rca CTC-9A set: Just when I thought I had all the problems worked out , this happened last night. It is more of a snaking in the picture from the bottom to the top and when you bring up the brightness to the normal setting , the picture bloomes. I have checked damper and horiz output tubes on the tester and they ck ok. and V-11,12,16,23 also V16 The Focus tube a 1V2 I don't have the setting on my tube chart to test it. Could this also be a bad capacitor problem. thanks chip

How olds' the picture tube? sounds like its gaseous. I had the same problem with an old '65 color vintage RCA. Bad pic tube. I also had a bright stripe that ran top to bottom just to the rite of center screen. All the experts back then told me that the flyback was mismatched impedance wise. It was an aftermarket as opposed to an RCA OEM part. Who knows??? Anyhow, it sounds similar to the problems I was having. Also check the hivolt regulator tube.

Steve

:How olds' the picture tube? sounds like its gaseous. I had the same problem with an old '65 color vintage RCA. Bad pic tube. I also had a bright stripe that ran top to bottom just to the rite of center screen. All the experts back then told me that the flyback was mismatched impedance wise. It was an aftermarket as opposed to an RCA OEM part. Who knows??? Anyhow, it sounds similar to the problems I was having. Also check the hivolt regulator tube.
:Strike the hivolt reg tube you said that, NEVERMIND.
Steve
:Steve

OK: Steve I did replace the picture tube a few weeks ago with a GE 21CYP 22A , so today I hooked up the original RCA Colorama tube and I have the same problem, so I know its not the crt. The HV rectifier tube is a 6BK4 and I don't have that tube listed on my tester chart, so I cannot test it to see if it is good, can you tell me what socket and setting it takes.thanks chip

6BK4 is the voltage regulator tube. The high voltage tube is most likely going to start with a 1 or 3.

Also be sure to check any resistors in the high voltage circuit. A drifted resistor in the kilovolt circuit can cause blooming. 6BK4 should definitely be checked, too. If you have a high voltage meter, you can check to see if the regulator circuit is operating properly. My 1957 Pict-o-Guide says that the voltage should normally hold at 19,000 volts (for a 1957 set). An inoperative regulator circuit will go from 20,000 volts at full raster to about 27,000 volts for a dim raster. I think that I have settings for the 6BK4 on my EICO 625.....which may or may not be meaningless to you. I will look in the morning.

If you are also actually having problems keeping the horizontal circuit in sync, you should of course check resistor values, tube emissions, and frequency adjustments, but you should also check capacitors for arcing, and replace capacitors if in doubt. I don't think that you are actually having a horizontal oscillator adjustment problem, but I had a jittery oscillator in my RCA 630TS, and it was due to an arcing 82 pf (if I remember correctly) capacitor that feeds sync. into the horizontal circuit.

T.

OK: I have a TEST O MATIC tube tester which has X Y Z selector settings A-I for X and Z and Y is a number setting. not a very good tester but all I have . I do know that capacitors were changed in the vertical circuits awhile back . The cans are all still original also. chip

For my EICO 625, the settings are: filament: 6.3; for the pins: down (common): 1,2,3,4,6,8; center (filament): 5 and 7; up (meter): 10. 10 connects to the grid/plate cap lead. The grid/plate cap lead is then to be connected to the plate cap on top of the 6BK4. The meter shunt setting, labeled simply SHUNT, is to be set to 100, which inserts the greatest resistance across the meter, allowing for maximum deflection. The SELECTOR switch, which controls voltage and current, is to be set to #4, which is the maximum current and voltage setting. I think that it sends 200 volts to the meter circuit through a 1200 ohm 5 watt resistor. I can't be too sure, though.

If you have a schematic for your meter which gives voltage and resistance values, you may be able to adjust it so that it performs a similar test on your 6BK4.

T.

Sorry....should say, "if you have a schematic for your tester..."

T.

The tubes in the horizontal and HV section cannot be tested on a tube tester, the results are meaningless. First replace the high voltage rectifier tube and start from there.

Dave

OK: I don't have that kind of meter anyway and I did order some replacement tube last night, But when you get into replaceing resistors and such, that way out of my line,I have done a few recaps on a few sets and have been successful. But would need to send the chassis out for critical repairs,would any of you be interested in checking my chassis if the tube replacement does not work . thanks chip

Checking and replacing resistors is easy. You just disconnect one lead of each resistor as you test it, and then measure its resistance.

Checking frequency alignment is more difficult (requires a signal generator, and possibly a scope), and checking coils for troubles is even more difficult.

Your problem most likely lies in the high voltage circuit, though, as Dave said. Start with the high voltage rectifier. Then test any resistors on its socket. Then try replacing the 6BK4 with a NEW one. Then, if that doesn't do anything, check resistors and capacitors associated with the 6BK4.

Testing the 6BK4 and the high voltage rectifier does tell you a little bit. It at least tells you that the tube has fair emission. However, a tube tester cannot begin to put those tubes under the stresses that they normally see, so a tube tester's indication is somewhat meaningless. The best test for the 6BK4 is with a high voltage probe--check to see that the high voltage is being regulated properly. Blooming pictures happen when the high voltage goes down a bit from a bright raster. It takes more energy to focus a higher voltage beam than it does to focus a lower voltage beam, and so if the beam voltage goes down, the focus circuitry won't be focussing for that voltage, but instead for the higher voltage.....unless, of course, the focus circuitry is also automatically regulated. An ideal television has good regulation in both the high voltage and focus circuitry.

Fluctuating high voltage is caused by several things: weak high voltage rectifier, drifted resistors in the high voltage circuit, or an improperly functioning regulator circuit, either caused by a bad 6BK4 or its associated circuitry.

T.

OK: I did check my Electrolytic caps and found that after having the set on for 10 to 15 mins C-2 is running very warm and when I tap lightly on the top of the can I get a vibration type effect on the screen. This does not happen when I tap on the other cans. thanks chip

Not sure why the screen is vibrating, but caps should not get warm. Perhaps they may during re-form, when a set is turned on after decades of being off. However, during otherwise normal operation, they should not get warm. Any electrolytic that has had at least 30 minutes of use should have no less than 1 megohm of leakage value-wise. That is, numerically, it shouldn't be lower than 1 megohm. Even 1 megohm is questionable.

If you are in doubt, replace the electrolytic.

T.

OK: At the T1 I was checking voltages,

: OK: At the T1 I was checking voltages, the source point of C1 and C2 the schematic says 385V and at C2 270v and at pin 2 of V-8 140v. But when using my digital meter I cannot get a reading (with the set on). I must be testing at the wrong points. chip

If you haven't replaced the filters and caps there is no sense in trying to troubleshoot it. You just can't fire up an old set and expect it to work for any length of time before something burns up.

Dave

Yes: Most of the caps have been replaced, I know in the vertical circuit boards, But the cans were not, I have had the set working for about 3 months until this happened, But it was in storage for many years.