maybe one of you can give me an idea where to go , only has a vertical line that you can't do anything with , you can see it react when you do the height , lin , even the expander switch but it stays a line but you see it reacting , it doesn't grown, the output tranny reads ok in ohms , its tough to figure out all the voltages since they aren't writen and this is all there is , no other sams coverage , no service manual , any idea what to do ? should i be looking at the osc ? i don't know the voltages ( all of them on the osc or output they aren't writen on schematic ) l70 seems ok too.

http://www.cerant.com/TV/TV%20Zenith%20TV%20Model%202438RZ1%20Chassis%2024G 26Z1%20Porthole%20Type%2016%20CRT%20-%201950%20/00%20RESTORATION%20PROCESS/SDs/SD24G26.pdf

thats the schematic

thanks
mike

If it is a vertical line then there is nothing wrong with the vertical. You have a problem in the horizontal but it would be after the flyback since you can see a line on the screen. Maybe an open horizontal coil on the yoke (L61 or L62)?

what i meant is a line going across the screen , a horizontal line showing that there is no vertical sweep, i didn't think of trying the yoke but could check there.

mike

Voltages are listed on Riders schematic. Unfortunately I don't have a way to scan or copy the large format pages. Here's a picture of the vertical section. PM me an email if you can't read it here and I'll send a higher resolution picture. [edit] Well that's not going to help you much, I see it's the same schematic as Sams. But there are some tube pin voltages listed on both.

http://i452.photobucket.com/albums/qq245/Kuehn/24G26Vertical2_zps5e504c91.jpg

http://i452.photobucket.com/albums/qq245/Kuehn/24G26Vertical4_zps3c3c64d7.jpg

all i can recall is that pin 3 of the 6v6 is the right voltage , i have to make notes on the voltages , also forgot to point out there was a 6w6 in the 6v6 socket - why i don't know , no idea if it would work with that in there either.
thanks for the pic .

mike

Here are the voltages - 6V6 pin 1 is 0 volts , pin 2 is -8 volts , pin 3 is 400 volts , pin 4 is 400 volts , in 5 is 115 volts , pin 6 is 68 volts , pin 7 is 0 volts , pin 8 is 37 volts ..... 6sn7 pin 1 is -28 volts , pin 2 is 78 volts , pin 3 is 0 volts , pin 4 is 3 volts , pin 5 is 5 volts , pin 6 is .640 volts , pin 7 is -8.5 volts , pin 8 is 0 volts.

looking at the schematic it looks like the osc 6sn7 is not right with voltages , why ? i'm trying to figure this out.

mike

there was a 6w6 in the 6v6 socketMy tube references do not list those as interchangeable (although they appear to have the same internal diagram).

This page lists data sheets for both tubes:

http://tubedata.milbert.com/sheets69.html

Perhaps comparing data sheets will tell you whether 6W6 is a reasonable sub for 6V6 in this particular circuit.

Phil Nelson

could the intergrator be the fault ?

Is it safe to assume you've replaced all the paper and electrolytic caps, as well as checked resistor values in the vertical circuit? That would be the first step. Not sure how you're getting 115V on pin 5(grid) of the 6V6, unless you're measuring AC volts? There should only be a 3.3 meg resistor going to ground and one end of a .1uf cap tied to that pin. Pins 2 and 7 are the heater supply and should have around 6.3Vac across them. Pin 6 has no internal connection to the 6V6 and must be a tie point for some other point in the circuit. Better double check the wiring around that stage.

yes its been recapped and resistors checked , will double check them , i will check the wiring around that stage , seems like the 115v should be on the 6sn7 not the 6v6 , its like the voltages are reversed.

mike

maybe one of you can give me an idea where to go , only has a *horizontal* line that you can't do anything with , you can see it react when you do the height , lin , even the expander switch but it stays a line but you see it reacting....

mike
Could you describe how the line reacts, ie., does it jump up and down, change brightness, or what?

Are you using a digital meter to take voltage readings? If so, do you by any chance have an analog VTVM that you could use instead?

Could you have disconnected the 4.7meg resistor R55 and accidentally re-connected it to the other side of the 0.1uF coupling cap C63? That might explain why you have 115V on the grid of the 6V6, 5V on the plate of the 6SN7, and lack of vertical sweep.

c62 which is .01 was never changed , it was a micamold that was tucked under L70 and hidden , so i replaced it and i seen sweep , it was letterbox but i wasn't running at full voltage either , one cap could ruin your whole day , this is why i've had the arguement with a couple people that its impossible to make a set run with the original capacitors all it takes is one , so assuming that the vertical wasn't full because i was running at a lower power the problem is solved , i wouldn't have found this if you didn't ask about the 4.7meg resistor which might not be 4.7 in the set , that and r57 may not be the same values as in the schematic , but progress has been made

mike

ok at full voltage letterbox and it wont get bigger so this shouldbe able to be resolved easier ( i hope ) then the previous issue , also an arching that happend below the 1b3 socket - thats why i wasn't running at full power , what a snap/pop it makes and then it could be seconds or a minute later before it does it again

mike

an arching that happend below the 1b3 socket Clean the entire HV area, especially that socket, with isopropyl alcohol (rubbing alcohol). Also look under the 1B3 socket for resistors. I have found burned ones there.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

i might replace the resistors , the arc i thought was at the tube socket , well whats happening is theres an arc at the rim of the crt where its held down to the chassis and when it arcs there it arcs at the same time at the tube socket , now if it were just the tube rim why would it cause it to happen at the rim of the crt ? must be the reverse it happens at the rim and causes it to occur at the socket ? , i will take off the part thats supposed to insulate the rim from the chassis and clean it , perhaps even the doorknob is at fault causing the issue.

mike

the plastic ring protector that goes around the rim of the crt had a couple cracks in it , i put electrical tape over the cracks and multiple layers around the metal piece that holds the crt , the plastic ring is supposed to insulate but wasn't properly after all these years , so it stoped arcing.
turned vertical height and it started to fill the picture but not as much as it should, so i'll have to check tubes , resistors , etc

mike

incase anyone is interested it is filling out and set is running but no horz sync or very little and vertical sync is nothing great either , so sync search.

mike

the fly - it gets hot , you can move the coating on it after running for 15 to 20 minutes , so either its being overdriven or its on its way out, it does show 12kv on the anode whick i think is normal for a 16ep4

the fly - it gets hot , you can move the coating on it after running for 15 to 20 minutes , so either its being overdriven or its on its way out, it does show 12kv on the anode whick i think is normal for a 16ep4


Make sure you have both 6BQ6 Hor. Output tubes and they check OK.
There is a common 100 ohm Cathode Resistor (R83). I read that the
cathode current should be less than 100ma. Instead of putting an
amp meter in series, measure R83 to see how close to 100 ohms it is.
Then power the set and measure the voltage across R83. Then
calculate the current. I understand too much current in R83 will overdrive
the Flyback and cause it to heat up.

There is an adjustment that affects this current - Hor Drive.
Adjust for best picture and less than 100ma.


Carl

i don't have an amp meter but can turn the drive as low as possible before the screen starts squeezing , i will check the 100 ohm resistor , i'm pretty sure i already did

mike

i just noticed my meter has AC ma and DC ma so i could measure the ma .... is it between the resistor and pin or the resistor to the ground or across the resistor ? this 100 ohm resistor is 120 ohms and replacement ( i put the 120 ohm by accident instead of the 100 ohm ) , its a power resistor , i could put a 100 ohm there or put a higher like 200 ohms to reduce the flow ?
also do i measure the ma at the horz drive or at the resistor? i'm just a little confused i never measured ma before or is what is on my meter not what i need to measure ?.

mike

I did not want to break the circuit so I measured the resistance.
Then powered th set with a volt meter across R83 - actually out of
curiousity I think I measured ac volts, dc volts, and used my
scope to look at the signal.
Then, I = E / R

Then adjusted Hor Drive to get current under 100ma

Let the set run for say 5 minutes, power off, discharge CRT anode, and measure temp.
These old Zenith portholes weak points are that they tend to eat up Flybacks. I wonder
if part of the problem is the way the circuit is designed and the other part the design
of the orignal Flybacks.

Carl

i don't have a scope or a way to measure the temperature , i did notice that the sizzle or static electric sound that comes from the fly goes away when you turn the horz drive but it might go away only when the picture is being squeezed a little , i supp ose i could turn it down and readjust the vert size and lin to compinsate but it still might squeeze things .
I= E/R this is why i'm not licensed because i'm terrible at math.... you then say adjust till i get 100ma but your saying do this with math ? if i measured it would be more accurate wouldn't it ?.

mike

I= current in milliamps


E= voltage


R= resistance


Volts(measured across cathode resistor) divided by resistance(cathode resistor value in ohms) equals the current flowing through the cathode resistor.

Example:

10 volts/100 ohms = .1A (100ma)

i did some experimenting and the closest i can get to .1 is .11 , thats altering the resistor from 100 ohms to 250 ohms , 27.5 volts divided by 250 ohms , with the 100 ohms you get 13 volts and .13 , so a 300 ohm resistor will probably take it down to .1 , i ran it with the 250 ohms and the fly wasn't getting hot , so i guess i'll have to either leave the 250 or raise it to 300 ohms .

mike

Mike, how does the video look with the 250 ohm resistor?

I've been told those 16EP4's were not aluminized and you can't expect
a very bright image. Best viewing is in a darkened room. It takes a
few minutes for mine to warm up before an acceptable image appears.

If you have a set with a 10BP4 CRT, the image will not be as bright or
sharp as the 10BP4.

This video is about as good as I was able to get my Zenith Porthole
in a darken room:
http://www.youtube.com/watch?v=aBdC_LdrZy0

Carl

Well picture seems ok with the 250 volt resistor , this set shows a nice picture with a brightner on it , i had one in the past with a really good 16ep4 crt and it was as bright as this one is with the brightener , you might want to check resistors in the brightener circut because my original one was dark and a friend pointed out that it could be a resistor and bingo it was brighter because a resistor wasn't right, this one you can see without a brightener things getting a glow where there shouldn't be getting that silver or negative look , this doesn't happen with the brightener.

i do get lines but incomplete vertical retrace lines with copyguard that are bright and come and go , unsure if doing the retrace remover will work , reminds me of a zenith color roundie it did the same thing ......one other thing is if i want to fill the entire screen and stretch the horz to compinsate to make things properly proportioned i can't unless theres something to alter to do it , the 10" mayflower you can do it to , you miss more of the image but don't get people who are too tall and thinner but it doesn't have the expander switch , i know they were designed to expand verticaly but they should have stretched horizontaly too like the stromberg 10" when you push the expander switch.
Carl your crt is ok ?

mike

Mike, reading your post makes me want to do as you suggested and
check the resistors in my Brightness circuit.

I have not hooked my 16EP4 to a CRT tester.
I did not have my Sencore CR70 when I restored the TV.
Next time I unbutton this TV, I'll give it a go.

Thanks

Carl

ok if you put a 300 ohm resistor there you get 30 volts across the resistor and it shows .1 ma , i have to rotate the drive a little so the picture will fill out on the sides but it remains 30 volts , even at 31 volts it remains close to .1

mike