Finding primary and feedback coils on CRT fly back transformer

Thread Starter

JosiahHalkias23

Joined Mar 4, 2021
2
Hi all,
I am trying to find the primary and feedback coils of a CRT fly back transformer, however is appears there are 3 possible primary coils and 2 possible feedback coils.
I know that the primary coil is normally pin 1 and 2 or which ever has the lowest resistance. However the resistance between the pins is as follows.

1-2 = 0 ohms
2-3 = 0 ohms
1-3 = 0 ohms
4-6 = 0.5 ohms
9-10 = 0.1 ohms

Does it even matter which one I use as the primary seeing I have 3 possible ones?
ZTFN35004A is written on the transformer if that helps.

Thanks in advance for any help.
 

Attachments

Delta Prime

Joined Nov 15, 2019
1,149
Hello there :) welcome to AAC.
Mostly tv and monitor flyback transformers have about ten pins at the bottom of the flyback. Each of the pin have a purpose or function as part of a complete circuit. The common pins that you can find in monitor flyback are: B+ pin, Horizontal collector pulse, ABL (automatic blanking limiter), GROUND, G1, AFC (automatic frequency control), VCC, HEATER (to filament) and X-RAY protection.
The B+ and horizontal collector pulse pin forms one winding which we call it as flyback primary winding. It can only can be test by using a flyback meter such as the Dick Smith Lopt tester flyback transformer pinoutor sencore LC102 and LC103C.Normal meters can't check this kind of fault. This is the most important winding compares to others and it can easily developed a short circuit when B+ voltage line or Horizontal output transistor (HOT) shorted. Sometimes a shorted internal capacitor in the flyback transformer may cause the primary winding to burn internally and the flyback became bulge and poured out the epoxy
 

MisterBill2

Joined Jan 23, 2018
9,274
A close examination of the wires going to those pins on the topside will reveal that some wires are larger diameters than others Those are the power winding connections. You may need a magnafier to see, but there will be a difference.
 

shortbus

Joined Sep 30, 2009
8,809
@JosiahHalkias23 Do you realise that the LOPT you have is probably a DC output not AC? Most of that stle have internal rectifiers and not knowing what you are going to do with it I thought it should be told to you.
 

MisterBill2

Joined Jan 23, 2018
9,274
At least some of them have exposed connections, and that is what I was thinking about when I posted my comment. NO, cutting away is a poor choice indeed, as it will probably destroy the flyback.
So the better approach, after getting accurate resistance measurements, will be to apply the output of an audio signal generator to the highest resistance winding and measure the voltage on the other windings. The voltage ratio at 15KHZ will be similar to the turns ratio, and probably the lowest resistance with the highest voltage will be the driving winding. That is because it will be the most turns of the thickest wire.
 

shortbus

Joined Sep 30, 2009
8,809
At least some of them have exposed connections, and that is what I was thinking about when I posted my comment.
Not that style though, the old black and white type that Aleph and HP were using in their project yes, but not the color TV DC output type shown here.
 

MisterBill2

Joined Jan 23, 2018
9,274
Not that style though, the old black and white type that Aleph and HP were using in their project yes, but not the color TV DC output type shown here.
I did provide a non-invasive method of determining which winding is probably the power input winding. That will also give the turns ratio.
 

MisterBill2

Joined Jan 23, 2018
9,274
So you want him to possibly destroy his coil by applying voltage randomly?
If you read the post, I suggested using a signal generator to apply a volt or so at around 15KHZ, and measuring the voltage at each set of terminals. That is not going to do any damage. That is far different from randomly applying mains power. The only voltage source was to be from a signal generator, usually just a few milliwatts.

Throwing stones is not appropriate for this website.
 
Top