A quick CTC 16 question

[JohnCT]

Don't put on a brightener or otherwise "clean" or boost the tube with a tester.

Put the service switch into the service position and advance the G2 controls to get a dim line on all three colors (just extinguished is better). Move the bias switch if you need to in order to get a line across the screen. if you can achieve this, put the switch back to normal and you should have a raster.

If you can't get a service line with your three G2s up or you can but aren't getting a raster, you need to troubleshoot this and not just guess that the tube is weak. For all we know, the last guy put the booster on it for the same reason you think it needs one - it may not.

John

[Aperna1985]

Originally Posted by JohnCT

Don't put on a brightener or otherwise "clean" or boost the tube with a tester.

Put the service switch into the service position and advance the G2 controls to get a dim line on all three colors (just extinguished is better). Move the bias switch if you need to in order to get a line across the screen. if you can achieve this, put the switch back to normal and you should have a raster.

If you can't get a service line with your three G2s up or you can but aren't getting a raster, you need to troubleshoot this and not just guess that the tube is weak. For all we know, the last guy put the booster on it for the same reason you think it needs one - it may not.

John

Honestly I don't know if it needs a booster. But I turned the service switch and got 2 lines I forget what color but I didn't see red. I want to say it was blue and white but I'm not 100%

I am getting snow on the screen and it changes with turning the dial.


I would like to make a test adapter if someone could help me out with that. This way I can tell if the guns are infact weak.

[JohnCT]

Originally Posted by Aperna1985

Honestly I don't know if it needs a booster. But I turned the service switch and got 2 lines I forget what color but I didn't see red. I want to say it was blue and white but I'm not 100%

I am getting snow on the screen and it changes with turning the dial.


I would like to make a test adapter if someone could help me out with that. This way I can tell if the guns are infact weak.

OK, you've got a raster. From what you're saying, there's a high probability it's got a weak tube. For the service line, the "screen controls" (I called them G2 in my last post) should give you a red, green, and blue line. White is most likely the green and blue superimposed. Normal procedure is to advance them until they light, then back off until they just extinguish. If you didn't see red, the red gun might be very weak.

Best thing to do if everything else seem good and there's no smell of something getting hot (btw, check the filter cans - none of them should be much more than room temp) then let her run a few hours. If the TV hasn't been run in 20 years it might pick up emission.

Regarding a tester, you can make a universal adapter using color coded clip leads that will work on any tube. I did this on my B&K 467 during the last of the RPTV years when I kept running into new projection tubes and B&K no longer supporting the 467.

What kind of CRT machine do you have?

EDIT: oops, didn't see you had a 465.. Those adapters are fairly easy to find and cheap enough, but while the 465 is a good tester, it's *brutal* on the tube for any restore functions.

John

[old_coot88]

If that's an isolation brightener and not just 'brightener', there's a chance it was installed due to a heater-cathode short. In any case, you need a decent tester to be sure what you got.

[EDIT.] If the britener has a switch, what position was it in?

[Aperna1985]

Originally Posted by Yamamaya42

OK..
THIS looks like the one.

If you really want to test the tube that is,

https://www.ebay.com/itm/12630797673...Bk9SR4689I7qYw

I actually Just bought it!

Originally Posted by Electronic M

One thing on the CTC-16 is the jumper wires on the chroma board tend to corrode open and they can kill individual guns and mess with HV regulator behavior...A number of newer chassis also have this and it's something to be aware of.

Thank you I wasn't aware of that. So I should be able to probe that plug and see if the voltages are missing right?

Originally Posted by zeno

Follow JohCT first with isolation on. You can follow almost any delta tube directions. We did the "just gone line" method.
Isolation is for H-K short. When it happens its usually int. When it shorts the bad guns cathode gets pulled to GND. This makes the screen BRITE of that color
with streaks & retrace lines. You can often LIGHTLY tap the CRT neck
to make it come & go.
SO try a set up & see if you can get a B&W raster. If you cant check the
CRT voltages on the K's, G1's & G-2's for next step.
BTW you can make a universal adapter. You need checker
schematic, cable connector, & those hook on test leads. It can check almost
any jug.

73 Zeno

I don't see any retrace lines, other than being blue it's a good picture. I'm wondering could I turn off all the colors then bring up one color at a time to see if all the guns work?

Originally Posted by old_coot88

If that's an isolation brightener and not just 'brightener', there's a chance it was installed due to a heater-cathode short. In any case, you need a decent tester to be sure what you got.

[EDIT.] If the britener has a switch, what position was it in?

I didn't see a switch, and it looks like it just does isolation not brightening. It would be nice of it was a chassis problem that someone tried to fix with the isolation transformer. Wouldn't the cups the dark if it was shorted? Like wouldn't it need to be a high hour tube?

Also surprisingly the filters didn't really get hot

[JohnCT]

Originally Posted by Aperna1985

I don't see any retrace lines, other than being blue it's a good picture. I'm wondering could I turn off all the colors then bring up one color at a time to see if all the guns work?

Certainly, that's the way we accessed the condition of those tubes back then. Turn all screens down and advance each one. They should roughly be the same but be aware that due to the color spectrum, the green will be the brightest, the red close but not as bright, and the blue (even with a strong gun) won't look as bright and crisp and the green and red.

If your blue looks good, the red and green should look better. From your description, you have a soft tube. It might perk up if you run it a few hours continuously.

Originally Posted by Aperna1985

I didn't see a switch, and it looks like it just does isolation not brightening. It would be nice of it was a chassis problem that someone tried to fix with the isolation transformer.

We don't know who worked on it and we don't know why he tried it or if he even knew what he tried was simply an isolation "brightener" (he may not have know the difference between a brightener, and isolator, or a combo device).

I worked on tons of those when they were daily drivers and while soft guns were common (I must have changed several hundred 21" roundies), heater to cathode shorts were not all that common in these tubes.

My guess is that they correctly diagnosed a weak picture tube and added the isolator thinking it was a heater boost brightener.

John

[zeno]

Follow JohCT first with isolation on. You can follow almost any delta tube directions. We did the "just gone line" method.
Isolation is for H-K short. When it happens its usually int. When it shorts the bad guns cathode gets pulled to GND. This makes the screen BRITE of that color
with streaks & retrace lines. You can often LIGHTLY tap the CRT neck
to make it come & go.
SO try a set up & see if you can get a B&W raster. If you cant check the
CRT voltages on the K's, G1's & G-2's for next step.
BTW you can make a universal adapter. You need checker
schematic, cable connector, & those hook on test leads. It can check almost
any jug.

73 Zeno