A Lemon set?

[radio nut]

My Muntz from a previous thread burned up the flyback. I have since bought one and will buy a back-up if the videokarma member can be patient with me(money is tight).
Maybe I should have known what was going on but here is what happened....

New caps and out of tolerance resistors replaced. The horizontal frequency did not have a scope picture to adjust it. the diagram said to adjust horizontal drive clockwise until the picture distorts and then turn counter clockwise a little and stop.

When I tried that The pic would not distort... the fly would squeal.

If I ran the set every day everything seemed fine. If I left it alone for a week then the set would come on with no pic and I had to turn the brightness up to see it. the crt still tests the same though, really strong.

Does this sound like a flyback or other issue? i have checked/ rechecked ALL resistors and they are still ok.
All tubes were also checked and still tested fine. Also I put in a new doorknob cap and did try subbing the horizontal circuit tubes. All of this was before the fly went POOF!

[Zenith26kc20]

If the picture seems to get too big to fit the screen and is very dim I would suspect high voltage (blooming).
I would think more along video or screen grid voltages on the picture tube are off value. I would check the schematic voltages and compare them.
Also, is the horizontal output or damper running hot (red plate)?

[holmesuser01]

How about the drive signal from the horizontal oscillator tube to the output tube?

Does the horizontal output tube run abnormally hot, but not red plate?

Did the old flyback seem to run hot? Most of my set flybacks get warm, but never uncomfortably warm to the touch.

[kramden66]

Yes good point the fly should not get too hot , if it does it is either overdriven , too much voltage going to it or the fly itself has a shorted winding.

mike

[radio nut]

Originally Posted by Zenith26kc20

If the picture seems to get too big to fit the screen and is very dim I would suspect high voltage (blooming).
I would think more along video or screen grid voltages on the picture tube are off value. I would check the schematic voltages and compare them.
Also, is the horizontal output or damper running hot (red plate)?

no on the blooming. when the set had sat for a week or sp it would turn on with zero picture until the brightness was turned up. I did in the middle of this issue recheck all resistors actually a couple of times before the flyback went poof. I will check all voltages with new flyback in it.
no red plate on the hot tube.

[radio nut]

Originally Posted by holmesuser01

How about the drive signal from the horizontal oscillator tube to the output tube?

Does the horizontal output tube run abnormally hot, but not red plate?

Did the old flyback seem to run hot? Most of my set flybacks get warm, but never uncomfortably warm to the touch.

Not sure if hot tube was too hot. What would that indicate? I do not have a scope to check horiz. drive signal. never checked fly by hand for temp. thought about it after I turned the set off but got shocked by something so I gave up.

Each time I ran the set day after day it seemed fine. With a week or two break it would come up with no pic until brightness turned up .

[radio nut]

Well, Two different problems I guess.....

I have not used this set for about two or three weeks since the fly went.
Out of curiousity I Rechecked the crt and turned the lights off after I set up heater voltage and turned it to emissions... Purple...... plus it took 20 minutes to get the needle into the good section....
thinking crt leaking and going to air.
So all thats left is the fly.

[radio nut]

Well I put in a used fly I purchased from a Member and a different crt and so far the picture is good.
One side question.... I can't seem to get all of the buzz out of the sound. Hooked to a dvd player the sound has a slight buzz that starts as soon as the dvd player is turned on.
The same player does not cause any buzz with a modern tv. No matter where the audio If or other adjustments are put the buzz remains.
Can I add a cap to filter This?

If so what part of the sound circuit?

[Zenith26kc20]

Usually a leaker will come up to emission test fast as the air ionizes. When you turn the set on after sitting is it purple for a while. Any popping noises from the CRT?
My Magnavox was dark for a good while and slowly got bright as it ran. The CRT finally went PURPLE and that was the end of that one.
A new CRT cured that.

[radio nut]

No on the popping noise.

The old fly was probably bad to begin with on this set. When I set up the horiz. sweep the fly would squeal when I turned the drive adjustment clockwise as the diagram states. The replacement fly will eventually distort the picture like the diagram says. so once I get the sound buzz figured out I will be happy. Oh it does quit buzzing at full or really high volume!

You are correct that it would eventually get brighter after it ran. Someone told me that a gassy tube could pull more power. If they are correct I am lucky that I do have a spare crt!

[kramden66]

try unhooking one terminal on the antenna connection causing a weaker signal and see if it buzzes , is it doing the buzz durring everything or just text ?

it is a muntz so there are missing things inside that may be causing this

mike

[Don Lindsly]

Make sure the 1B3 is good. If the set uses porcelain insulators on the 1B3 socket, they go bad and cause blooming.

High voltage rectifier should always be replaced when changing flyback.

For horiz alignment, short the coil section with the cap and adjust for proper frequency. Then remove short and adjust the other end of the can for proper freq, then touch up a half turn to prevent "motor-boating".

Make sure the 180uuf horiz osc coupling cap is good. Replace with silver mica only.

Check HO tube screen resistor for proper value.

For sound buzz, check 4uf cap in sound detector and make sure the aquadag CRT coating is well grounded.

[miniman82]

Audio buzz can be cured with an alignment or a slight tweak to a coil or two in the IF strip, but you really have to be familiar with the set to go poking around without a scope. If slightly adjusting fine tuning cures the buzz but jacks up the picture, you need an alignment.

[radio nut]

Originally Posted by kramden66

try unhooking one terminal on the antenna connection causing a weaker signal and see if it buzzes , is it doing the buzz durring everything or just text ?

it is a muntz so there are missing things inside that may be causing this

mike

The buzz is worse on text but the set starts out pretty good. The buzz gets worse as time goes on.
Well, in the sound circuit I am using new caps and New ceramics.

Is the new ceramics a mistake meaning I should have used Mica?

[radio nut]

Originally Posted by miniman82

Audio buzz can be cured with an alignment or a slight tweak to a coil or two in the IF strip, but you really have to be familiar with the set to go poking around without a scope. If slightly adjusting fine tuning cures the buzz but jacks up the picture, you need an alignment.

Ok, will check. Just curious.....Does the yoke have to be pushed up against the bell of the crt or is a small gap normal?