1960s Sweet 16 RCA television help

[Dubis7]

Is the schematic showing up? I'm not seeing it. I have to run but I'll post it later tonight if not.

[Dubis7]

Okay, here's a copy of the schematic.

Also, this slipped my mind, but I did notice one of the leads to the electrolytic can was broken off when I was removing it. I've fixed it, and didn't consider it worth noting since I was planning to move it to a terminal strip anyway, but if memory serves it was the positive lead to the triangle symbol. Either that or the semicircle. Either way, Unless the symptoms persist once I get a picture, I'm tempted to chalk at least part of the "percussive maintenance" response to that lead being broken or almost broken.

Does anyone have any recommendations for what kind of wire I should get to replace the anode? Are CRT anode leads still sold, and will a standard piece fit most CRT sockets?

Also, I was a little confused on some of the information regarding my 1G3GT HV rectifier. If I'm understanding it correctly, that tube is not part of the series filament string, and is powered directly by the flyback transformer. I verified that my old 1G3GT was bad by testing for continuity between pins 2 and 7, which I believe is where the filament is. Those two points tested no continuity, and further testing on a tube tester also showed no life.

Also, since I'm on the subject, and I apologize for asking these novice questions, what's the standard on numbering tube pins? If I've read correctly, I find the key on the center post, or gap on a miniature type tube, and count clockwise from there. Am I doing that right?

If everything I'm doing so far checks out, My next step is going to be to test that resistor and, assuming that checks good, verify that there is an intermittent break in the anode lead.

[dieseljeep]

Originally Posted by Dubis7

Okay, here's a copy of the schematic.

Also, this slipped my mind, but I did notice one of the leads to the electrolytic can was broken off when I was removing it. I've fixed it, and didn't consider it worth noting since I was planning to move it to a terminal strip anyway, but if memory serves it was the positive lead to the triangle symbol. Either that or the semicircle. Either way, Unless the symptoms persist once I get a picture, I'm tempted to chalk at least part of the "percussive maintenance" response to that lead being broken or almost broken.

Does anyone have any recommendations for what kind of wire I should get to replace the anode? Are CRT anode leads still sold, and will a standard piece fit most CRT sockets?

Also, I was a little confused on some of the information regarding my 1G3GT HV rectifier. If I'm understanding it correctly, that tube is not part of the series filament string, and is powered directly by the flyback transformer. I verified that my old 1G3GT was bad by testing for continuity between pins 2 and 7, which I believe is where the filament is. Those two points tested no continuity, and further testing on a tube tester also showed no life.

Also, since I'm on the subject, and I apologize for asking these novice questions, what's the standard on numbering tube pins? If I've read correctly, I find the key on the center post, or gap on a miniature type tube, and count clockwise from there. Am I doing that right?

If everything I'm doing so far checks out, My next step is going to be to test that resistor and, assuming that checks good, verify that there is an intermittent break in the anode lead.

There's probably nothing wrong with the anode lead. The schematic shows a 1000 ohm resister in the HV rectifier socket, check that.

[Notimetolooz]

Originally Posted by Dubis7

Also, I was a little confused on some of the information regarding my 1G3GT HV rectifier. If I'm understanding it correctly, that tube is not part of the series filament string, and is powered directly by the flyback transformer. I verified that my old 1G3GT was bad by testing for continuity between pins 2 and 7, which I believe is where the filament is. Those two points tested no continuity, and further testing on a tube tester also showed no life.

Very few tube testers check HV rectifiers well. They don't apply high enough voltage and the tubes can't pass very much current even when good. The filaments are higher resistance than normal because they run on low voltage and draw little current.

[Notimetolooz]

You should check the voltages on the CRT socket, they have to be correct also in order to get light on the screen.
You might have got on the wrong track looking at the HV because some of your tests weren't conducted right.

[Dubis7]

Thanks for all the advice. I went back and did another filament continuity test of the original tube, and it looks like my original tube wasn't faulty.

I also went ahead and restested that 1K resistor under the rectifier socket. The results were mixed. An ohms test across the resistor with the tube removed is reading just about 1K, within tolerance, but a continuity test across the same resistor is showing no continuity. At the same time, doing another reading of the anode wire is showing stable continuity when I flex the cable, so I'm inclined to believe that's actually fine, but I'm also getting no continuity across that cable when I measure from the opposite side of the resistor. Is that normal, or is the resistor suspect?

If my high voltage turns out to be fine, will it be possible to be seeing the same results if I'm not getting a signal to the tube? I'll have to go back and check with the anode lead plugged into the CRT, though I'm not sure of a safe way to pull back the rubber cup and look for the spark. Gloves perhaps? If anyone has a method for that, I'd love to hear it.

[dieseljeep]

Originally Posted by Dubis7

Thanks for all the advice. I went back and did another filament continuity test of the original tube, and it looks like my original tube wasn't faulty.

I also went ahead and restested that 1K resistor under the rectifier socket. The results were mixed. An ohms test across the resistor with the tube removed is reading just about 1K, within tolerance, but a continuity test across the same resistor is showing no continuity. At the same time, doing another reading of the anode wire is showing stable continuity when I flex the cable, so I'm inclined to believe that's actually fine, but I'm also getting no continuity across that cable when I measure from the opposite side of the resistor. Is that normal, or is the resistor suspect?

If my high voltage turns out to be fine, will it be possible to be seeing the same results if I'm not getting a signal to the tube? I'll have to go back and check with the anode lead plugged into the CRT, though I'm not sure of a safe way to pull back the rubber cup and look for the spark. Gloves perhaps? If anyone has a method for that, I'd love to hear it.

Take a small thin bladed screwdriver, use a clip lead clipped to the blade and to the chassis and work the blade under the rubber cup. You should hear a arcing sound even before the blade is fully inserted, if HV is present.

[Dubis7]

Okay, I just ran that test, and I did see a blue spark at the anode cup, so it's passing high voltage. I didn't hear anything, but I saw it, so I presume that's enough of an indicator?

Anyway, I suppose my next step is going to be to pick up one of those tube extenders so I can check the voltage going into the base of the CRT. I'll go ahead and re-verify that I didn't screw up any wiring or values when I replaced the capacitors. I've checked it multiple times, but since it was working before I got in there and isn't now, it's worth taking another look at what I did.

Does anyone have any suggestions on where to check next, in case I missed something?

[Notimetolooz]

Originally Posted by Dubis7

I also went ahead and restested that 1K resistor under the rectifier socket. The results were mixed. An ohms test across the resistor with the tube removed is reading just about 1K, within tolerance, but a continuity test across the same resistor is showing no continuity. At the same time, doing another reading of the anode wire is showing stable continuity when I flex the cable, so I'm inclined to believe that's actually fine, but I'm also getting no continuity across that cable when I measure from the opposite side of the resistor. Is that normal, or is the resistor suspect?

Is that continuity test on your meter a GO/NO-Go kind of thing? Is the indication a tone or light going on? If the test is this sort, then you must realize that the meter has a threshold to determine the result. If the threshold is below 1K then when you measure something with a resistance of 1K the meter will call it an open.
If the boost voltage on the CRT is that low it probably would prevent the beam from lighting the screen. It also would suggest that your HV was low. If the horizontal frequency is far off it would decrease the HV.

[Dubis7]

Originally Posted by Notimetolooz

Is that continuity test on your meter a GO/NO-Go kind of thing? Is the indication a tone or light going on? If the test is this sort, then you must realize that the meter has a threshold to determine the result. If the threshold is below 1K then when you measure something with a resistance of 1K the meter will call it an open.

I looked this up after the fact, and yes it appears that my meter was probably responding to the functioning resistance of that resistor as if there was no continuity. That was my bad, but at least now I know that's how that works.

Sorry for the late response, all. I was out of town over the weekend, but I'll run those voltage checks sometime today or, if not, Thursday and see where I am.