ctc12 clone beam current

[timmy]

so L13 measuring this is ok, ill put it back in, bty there is only 2 legs on the L13 so how could anyone tell if its bad. and the brightness pot measures 242k .

[DaveWM]

fyi for future ref, you generally do not need to pull peaking coils out just check them in circuit, you should see low ohms.

[timmy]

Originally Posted by DaveWM

fyi for future ref, you generally do not need to pull peaking coils out just check them in circuit, you should see low ohms.

ok, good to know as these boards are so brittle and i hate messing around them, traces break, ect...

[timmy]

the 3rd video tube 6ej7 on my tester has the grid emission needle jump up in to the area of rejection but only when i press the button it then goes back down and also the neon light that indicates shorts flashes when the needle jumps. would the 3rd video tube possibly be responsible for the 20+ volts on the video out tube ?

[DaveWM]

nope dont think so.
I will be doing a video later to see what it normal

[Username1]

Hi Guys, sorry I was all tied up for the last few days.... I've read all the fun
since I was here last, and it seems to me you guys have not resolved the odd
voltages on the 12BY7A....? If that is correct, I was wondering if you checked
the following resistors.... R146, R148, and R139 See attached images so we are
all thinking of the same parts....

Just in case it's not an open feed to the plate, but biased to that 20V grid take a
look at C729, when you follow the path through R133 and L708 it runs over to
a 17V point on the Sync Sep 6AK8 and AGC control 6K 2W, that's got to have
a very influential amount of current.... So if'n C729 is being bad, that could
take the grid strongly to 20V..... Wadda-ya think....?

Heater and other stuff tied me up at wife's parents house, snow might do it
to me for tomorrow, let me know if you got that 12BY7A under control....'OK'

.

[DaveWM]

The .1 in the grid circuit could cause a prob, but none of the ones I have ever worked on have been bad (leaky). I hesitated bring that one up for that reason AND the fact that its in a kinda busy area of the circuit board.

I am pretty sure he says he has checked those power resistors around the setup switch. one easy thing to check is to see if the plate voltage goes away from the 12By7 in the service mode. It should not, but if it does one of those resistors is bad.

Hopefully the problem will be resolved with as little need to remove parts as possible to test.

I am going to be making some videos later, and will be checking voltages both a the CRT pins and the video out.

[timmy]

what was the plate of the 12by7, #8 or 7 . ill check to see if the voltage goes away in service mode but yes i did check those resistor around the service switch all but one i didnt cut from the circuit because being very close to the service switch, but ill have to check it for sure. i did check it but all and all i may have got a feed back reading in circuit. the.1 cap is this the cap at the grid of the shunt tube ? im sorry im editing again, i guess the .1 you talk of is the one next to the 12by7 i check in my simple way by using the dvom and it went to infinity .

[Electronic M]

Anything short of a vintage eye type cap checker such as the Heathkit C3, is a lousy way to test capacitors. Most caps will fail from minute leakage currents that are too small to measure on a modern low voltage device. Caps need to be checked for leakage at full rated voltage for a test to be meaningful.

[Username1]

Did you change out that tube with one from your other set....?
You should not leave any item overlooked with this set, as it already
looks like no one here has yet to see a similar problem like the
ones you are having.... And it took quite a long time to make the
progress already made....

There has to be a reason that tube grid has +20 on it..... I would
focus on that first.... It means that tube is on - hard on.... And the
plate voltage should be low..... First cause is that +20.

I agree on those Heathkit Cap checkers.... I got a IT-11 I think it is....
smaller one than the 3.....

.

[timmy]

Originally Posted by Username1

Did you change out that tube with one from your other set....?
You should not leave any item overlooked with this set, as it already
looks like no one here has yet to see a similar problem like the
ones you are having.... And it took quite a long time to make the
progress already made....

There has to be a reason that tube grid has +20 on it..... I would
focus on that first.... It means that tube is on - hard on.... And the
plate voltage should be low..... First cause is that +20.

I agree on those Heathkit Cap checkers.... I got a IT-11 I think it is....
smaller one than the 3.....

.

yes i changed that tube for sure. and yes the focus now is this new problem with the voltages on the 12by7 and i dont want to overlook anything at this point at all.

[timmy]

L13 shows 2200 ohms in paralle with the coil so how is anyone able to check this if its inside the coil , it measures 6.5 ohms ?

[timmy]

right now no voltages go away from the 12by7 with the service switch in service mode. so now i am going to lift one leg on each of these 4 resistors, r- 60, 61 ,62 , 63 , and check them. why would a resistor show it as 150k but under that it shows 270k,are they saying it could be either one ?

[timmy]

ok r-60- 10k =12.40 k 61-2200 ohm =2335 ohm 62 150k = 156k 63 330k =.330 meg i guess they are all good, something is bad here, where the hell is it, lol,lol.....

[timmy]

any possibilty that the L22,24,26 coils may have anything to do with anything ? i ask because i once took one of these off the board to repair one wire inside thinner then hair and i was lucky i had a magnafying glass. who knows what was done to the set befor i got it maybe things were shorted out like the .001 cap and the focus coil got hot, im just grabbing at really small straws.