1960s Sweet 16 RCA television help

[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?

[zeno]

Resistors should be check with one leg lifted IF they check
bad in circuit. After a while you get the hang of which to
do & speed things up.

For now check pin 2 of the horz out tube & be sure its about -20 VDC.
If not its a dead horz osc stage.
Also check voltages on the 8FQ7 & 22JU6 & post them.

73 Zeno
LFOD !

[Dubis7]

Okay, well, the new Mixer/Oscillator tube came in today. I swapped that and have been running it with the back on for hours now. Haven't had a single issue, everything seems rock solid, and it considering the previous behavior it would have started acting up by now. So I'm going to say I had some sort of intermittent issue with that tube. I may swap the old one back in later and see if the failure comes back, just to prove it, but so far so good.

[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.

[zeno]

Originally Posted by Dubis7

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.

Continuity is zero or near zero ohms. My fluke has a beep & a scratchy
tone. A beap is 0 ohms. If you wiggle something like a connector with
a rusty connector it will make the scratch sound.

Many meters have range select & auto range also so watch for that
when measuring,

73 Zeno
LFOD !

[Notimetolooz]

Usually a continuity test is for things where you expect the resistance is very low, maybe no higher than 10 ohms. It is really for testing wire, contacts and switches. You can also use it on things like filaments and modern speakers. If it is a resistor use the ohms measurement, otherwise you will just confuse yourself.

[Dubis7]

Okay, so I may have broken something, but it may not have been something I did.

I got the voltage measurements. For my 22JU6:

1: Unused
2: -20V
3: 0V
4: .3V
5: .15V
6: Unused
7: 120V
8: 37V
9: Unused

For the 8FQ7 (I checked then all because it's easier to access the pins above the chassis):

1: 0V
2: 5V
3: 8.6V
4: 109V
5: .04V
6: .06V
7: 5V
8:2.3V

Then, I measured Pin 9 on my 8FQ7, and the yoke started squealing and sparking. I see no indication that I shouldn't measure that pin on the schematic, and I fact, looking underneath, I don't even see anything hooked up to that pin, nor any mention of it at all on the schematic.

It looks like a wire may have broken on my yoke. I'm attempting to attach a picture, but I'm on mobile so I may have to do a separate reply for that.

So basically here's where I am: I don't think I should go any further without looking this yoke over. Is there a way to check if it's okay? If I do have a broken wire (it's accessible, but small) what are my repair options? If the yoke was having trouble, could that be causing my low high voltage problem? Also, from the schematic, should I be safe to measure pin 9 of my 8FQ7? How do my other voltages look? Some of them seemed off to me.

[Notimetolooz]

Your 22JU6 voltages are fine except pin 8, you got 37V but it should be 25V.
You should measure on the other side of R77, the voltage should be near 145V. Also check the value of R77, should measure 47K.

Your 8FQ7 are nearly all wrong! Did you measure the wrong tube?

Yes, check out the yoke. Perhaps there is a short or maybe is arced because the voltage got too high somewhere.

When you measure the filament pins you need to use the AC volt ranges.