you can still get a solid 25kv on the raster from full bright to full dark right?

if so you need to focus on that crt setup. starting with the checks of voltages at the yellow stripped leads as detailed above. The setup does not seem to be working, need to find out why is so touchy.

So lets say you put on the Honeymooners, there is a nice steady watchable picture...?
And this blooming that happens, it's during regular programing ?? And if it is -
when you leave the G's Screens, and Kine Bias alone, and turn the front of the set
brightness, and contrast back and forth slowly it seems to work ok.... or not...?

And if you turn to a raster only spot no snow between stations between detentes,
you have a blank screen and if you leave it, the screen is steady...?

And in that spot, adjusting only screens, or bias, causes the blooming...? Are the drives
not effected.... They don't cause any blooming....?

.

i just looked at the crt ground where the chassis makes contact with the foil strap and its black on the chassis like coal dust as if its not making good contact and some wipes off.

yr 200v hi low 232v yg hi217 low267 yb low 216 hi 266 v bias pot up and down bright screen

all 3 of those yellow with stripe should be closer to 300v (crt cathodes)

all 3 of the solid color RGB wires should be closer to 200v (crt control grids)

all 3 of the white with stripe should be around 600's (crt screen grids)


the yellow strip gets it voltage from the plate of the 12by7 should b about 300v pin 7

with the raster set to normal full brightness check those yellow striped wires again.

yellow wires red 250 green 255 blue 258 v
white wires red 730 green 622 blue 750 v
solid wires res 192 green191 blue193 v

these voltages are from setting it up for best picture and b&w screen. i can set them by voltage readings from sams but it wont be right. and the hv is at times low and does alittle dipping.

looking down on 12by7 going counter if thats 7 its 145 volts

and that is with the kine bias fully CCW? no wonder it blooms instantly
and turning the kine bias CW just reduces those even more?

You did say this CRT tested fine for emissions and cut off right?

the crt cutoff was close for the red but better on the other, and the bias is ccw. otherwise emissions good

that cant be right, pull 12By7 the tube out and check that voltage again (with tube out), should be at least 300v

One thought on the HV regulation that only works without video issue: On my CTC-12 clone Silvertone, the HV regulator circuit has a lead (from it's control grid IIRC) that goes to the output of the luminance video amp through a high value resistor. I think that allows the video to have control over the HV, and if that line is bad on your set it could help explain the poor regulation with video present.

I asked him to look for that, think it was a 12meg. I know it was added starting on the CTC-15's

would be interesting to add it to an earlier set just to see if there is any noticeable difference.

I have him running down bias voltage on the CRT. they just seem way off.

I think the best idea is set it up for the decent brightness raster (not using the setup procedure since that does not work). with a solid 25kv from full bright to cut off.

then

get both the silvertones out, and compare one CRT lead at a time mainly looking for the bias between K and G1 and the required screen voltages, maybe even the horz out cathode current. set up both with rasters of approx equal brightness and HV both at 25kv.

tough dogs require really thinking thru the issue, in this case getting the HV under control (by having good shunts that do not short out) is just eh begining.
the hard part is determining just how bright max bright, how strong is the CRT, and whats going on as the controls are adjusted.

where was that 12 meg resistor ?

look around the junction point of the two 1.5 meg resistors, IF your set has one it will be there, but I don't think it is, if its a true clone of a CTC-12. I really doubt it could be the problem unless it has burned and gone down in value. Note it was not on earlier models.

i dont see it on the sams and i dont ever recall seeing anything else besides those 2 1.5 s . could the brightness pot be bad in some way, ill have to check it if it seems that this may be an issue.

with those voltages at the 12by7 not right im wondering even though the issue with the cap in the IF being shorted had anything at all to do with this latest problem by taking something out or a cap or resistor in some way even with the short only affecting a few filiments. and with this problem it does seem like it would affect the hv even in a small way would be a big deal by using up any surplus hv to be used when needed if the crt is being driven hard then there would be a loss of regulation, possible ?

c26 burned what are the odds of c25 leaking in some way or would it have an affect on these voltages?

I dont think there is anything wrong at this point with the HV, if you can get a decent looking raster and 25kv and it stays 25kv as you adjust the brightness up and down, then its working as designed.

The issue I think is a CRT bias prob, maybe a gassy CRT, something causing the problems getting the correct voltages to correctly drive the crt.

The HV holding steady from fully dark to full raster is key. The next issue is why the CRT cathodes (yellow) have to be so low to get the crt to conduct. That brightness range sure seems excessive I think you had -19 to +17 on the grid of the video out tube (based on the brightness pot). I don't recall checking that but it sure seems like a lot.

yes the 19 and 17 with the brightness at max and was able to bring the voltages near where they should be using the bright pot and raising the bias was ok and was also able to see the rgb lines in setup because the bias was up some and helped see those lines . but im sure the set was not designed to have the brightness halfway because if it moves then i would have to check voltages to get it back. almost as if the pot is raising to much, i dont know... as for the hv it starts out under 23kv and warming up it goes up but the key here is it dont jump like it did befor and sometimes it will go over 25kv and other times it wont so maybe there is something else going on here.

you should do some resistance checks of the 12by7 per the sams. the grid adjust the brightness pot while checking pin 2

ok ill do the resistance check on 12by7 per the sams, and ill run the set and monitor pin 2 voltage at the tube while lowering and raising the bright pot and note the differences. just want to make sure i got this, lol, lol.....

you could try this

brightness all the way down

service switch in service mode

advance screen drives one at a time to produce barely visable line

if any color can not produce line advance bias pot just until it does

adj all drives for barely visable line

back to normal mode

advance brightness pot just until normal viewing brightness

monititor HV and see if its holding.

if the above works then perhaps there is a problem with either:

brightness pot
grid emissions on video out.
check the plate voltage of the 6AW8 2nd video amp pin 3 per sams 30v with no signal present.

forget getting the lines as i raise the bias and again the blue rides in with the red the hv is up then its down bias up with the bright up hv droops as it did. i was only able to see the lines befor when the bright was adjusted to the voltages at the 12by7 that were close but its nopt working that way same as befor.12by7 pin 1-392 ohm 2-.530 meg 3 .4- fil 5 -fil 6- fil 7-6.40k 8 -3.44k 9-.4 now the 6aw8a i have a sub in there 6lf8 or i could put the right one back in, pin 3 bright low 43.7v high 38.8 v 12by7 pin 2-bright screen 20.75 v dark screen 12.5 v

12BY7 pin 2 = 20volts? My 12 schematic shows -1.7 volts. Negative in relation to the cathode.

im sorry all you guys this set when its done will be for sure a learning experience for us all, this set i guess has been down the road a few times or someone at one time didnt know what they were doing and really messed it up and now it needs the pros, lol lol... maybe c39 slightly shorted.

dont know if this helps rule out a gassy crt but with the crt cap plug off the voltages at the 12by7 dont change they stay the same as i took the readings again, this time pin 1 has 0 volts pin 2 -12.5 low bright and 20.75 volts bright high pin 7 145 volts pin 8 134 volts. seems there is something else going on in this set because these voltages are certainly not right, since pin 1 looks like it should have 10 volts and #2 and #7 are the other pins with the wrong voltages.

it may take a few days, but hang in there.

I plan to make a video showing all the pin voltages on the CRT of my working well CTC-12 that will give you a good frame of reference.

Note sams voltages can be all over the place, they are way off compared to the RCA field guide as an example.

Esp CRT settings since they have to be tailored not only to the CRT performance but many other variables (not the least of which is individual taste of "correct" brightness).

i went back and double checked the pin 5 of the shunt voltage is 380 volts while pin 2 is 391 a difference of 11 volts compared with 370 and 385 is a 15 volt difference. just figured i would check to make sure nothing else happened there since i had some time to do so. i dont know if a few volts difference there would make much difference with the hv.

I assume you mean pin 1 and 5 the cathode and the grid?

you can run pin 1 up and down with the hv adj pot. this sets up the overall bias and determines the current shunted by the tube. bigger the difference the (cathode pin higher that Grid pin) the less current flows thru the tube (to a point until its cut off completely and no current will flow). Less current thru tube, the higher the unloaded HV will be (assumes CRT is blank and not drawing any). the voltages ref in sams are "prob" just a reading with the a blank raster as most of the time there is a statement about "no signal" and using a VTVM, setup for normal viewing etc...

things to consider, the type of test equipment used (in this case its prob supposed to be a VTVM)
line voltage
no signal (unless specified like in some of the chroma test points, which is typically color bars)
+/- tolerances ofter 10-20%
resistance and voltage readings are just the starting point and not the only thing to look at if something is not working right.

yes , im sorry this test was with the tube in pin 1 and 5 to ground

i tried that hv pot up and down it dont swing much at all only a few volts on the grid. your opinion, about putting the 2 1.5 m resistors back in which are now 1.6 m would this just lower the hv overall or leave the 2- 1 megs in if it benefits the hv circuit.

I don't like to re engineer tv's so I would put the correct resistors in there.

That being said other that I think it will work the same, just with the HV pot in a different position to get 25kv. You will just be moving the math around a bit on the voltage divider requiring resetting the HV pot.

i have a bit of a problem the 6gm6 has c25 and c26 off pins 3&4 these caps go to ground the sams shows nothing else but 3-4 to ground but i am getting k readings on both pins to ground, this is not right as a .001 should not show anything to ground. this tube is ccw as the rest ? im seeing 81 k on both pins to ground..

if the filament wires are attached to the board then you are seeing the resistance of the B+ voltage divider to ground that is used to float the filaments.

ok that makes sence but in your video the voltage you had at pin 1-2 showed 211volts mine shows 220 volts closer to the 225 v limit 211 v would be better i would think.

maybe i should have changed them both c25 and 26 to be safe. if the other cap was leaking just a little bit , would this affect the heater voltage or the voltage at the shunt, like the other.this other cap is on the side of the resistor divider.

lift the all the leads off the junction of the 150k/180k resistors and read the voltage, should be around 180-190v

reattach the leads, it should not change. if it does then there is leakage, somewhere. could be those caps to ground (.001/.001/.1) or a KH short in a tube (the IF tube/shunt tube/CRT).

if it does not change you are good to go.

if it makes you feel more comfortable to change by all means have at it, just make sure the cap is rated at least 400v to be safe (double what it is likely to see)

i just want to cover all i can and not overlook anything. i took the 3 tubes out that use the z y connection but i would still have to remove the connection from the diode and the gound via the resistors then check those z y heater leads to ground there should not be anything readable, i hope. i will change the other cap .001 i will use a 102k 1 kv its supposed to be a .001