• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

identifying the flyback pinout

RetroGamerCX

New Member
hi, i'm new here, and today i saw this tutorial and decided to do this experiment. the problem is that i don't know the pinout of my flyback, and i only have 1 flyback and i'm afraid to accidentally burn it. my suspicion is that the primary is the first two pins with a large space. here's an image of the flyback:20201110_165912_HDR.jpg
you can see here that in addition to the high voltage output wire (the thick red wire), there is a black wire and a red wire, both connected to two potentiometers; and each of these potentiometers has a function, one is used for the focus, and another is for the screen. can i ignore these potentiometers or can i somehow use them to adjust the flyback output?
the flyback model is kfs-60226b. I tried to find the flyback pinout by searching, but I didn't find anything
 

shortbus=

Well-Known Member
Most Helpful Member
Did you see this site? Didn't read all of the site but has a lot of information on the kfs series of LOPT. You are aware that it probably is what the call a DC or diode output LOPT aren't you? The one in your Youtube link is an AC type. If you got yours from any modern color TV, which what you show looks like it is, and from the part number, it won't do what the guy in the video is doing. Well that is kind of a wrong statement, it can be done but not very easily.

http://obsoletetellyemuseum.blogspot.com/2010/06/lopt-flyback-eht-transformer_48.html
 

RetroGamerCX

New Member
yes, i know the guy is using an ac flyback, i saw a comment in his video asking if a dc flyback will work, and the guy answered yes, but with a dc current output. and yes, I will read this website that you mentioned
 

RetroGamerCX

New Member
well, the website explains very well how flyback works and the history of televisions, but the problem is that I didn't find any pinouts on the website, which is what I'm looking for
 
Last edited:

RetroGamerCX

New Member
here's the schematic diagram of the flyback:
hr7494.gif
it's a little confusing, but it's a little bit understandable. apparently in pair 1-2 which is my suspicion for the primary, pin 1 is connected to the collector of a transistor, and this collector pin is also connected to a diode, which has the other terminal connected to the emitter of that same transistor, and pin 1 is also connected to one of the capacitor terminals, so this is a rectifier. pin 2 is just the middle of the inductor; now i have 2 estimates: the first is that pair 1-2 is the primary, and the second is that pair 1-4 is the primary. because pin 4 is connected to the end of the inductor, and this pin is connected to one of the terminals of 2 capacitors and this pin is also connected to a resistor. there is a very high chance that both of my estimates are incorrect
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Pin 1 and 4 are the primary, pin 2 is a tap on the primary to feed another voltage rail, and will feed a rectifier - 'possibly' the supply for the video output transistors.

The diode across the transistor is the flyback diode.

+vcc is from the power, which is why it feeds the input of the transformer primary.
 

RetroGamerCX

New Member
so one of my estimates was correct, pair 1-4 is the primary. now i just need to connect the ballast cables to this pair and then i will be able to create tens of thousands of volts
 

RetroGamerCX

New Member
update: the flyback started to smoke. I think my ballast is too strong, it’s a 110w ballast, and that must have caused some component of the flyback to start burning, and for that reason there was no arc.
but it could also be that the ballast was so powerful that it ended up causing the flyback circuit to start having arcs inside (which is something very common), then the flyback's internal circuit ended up burning.
but something very strange is that even though the flyback burned, the flyback was not hot, nor the ferrite, nor the pins, nor the insulation, nor the ballast, the flyback just gave off a smell of burning graphite. and I don't know how to open the flyback to see if the circuit is really burnt
 

RetroGamerCX

New Member
sh*t. what happened is that pins 6 and 7 were actually very hot, and it burned a little bit of my table, which is made of wood. I think these pins suffered such an arc that they started to heat up, but since they are small pins and I left the flyback on for a short time, the pins quickly cooled down. so what happened is that there was actually an arc inside the flyback, most likely because of the high power of the ballast
 

RetroGamerCX

New Member
that must be why a smell similar to the smell of burning graphite started to rise, the wood on my table was burning. stupidity
 

RetroGamerCX

New Member
so, this means that the flyback works, the problem is that the ballast I chose is an overkill, because it’s 110w. the guy in the video I mentioned used only 40w
 

RetroGamerCX

New Member
which is still a little strange, because there are people who use zvs circuits to control flybacks, and these zvs circuits can usually produce thousands of watts
 

RetroGamerCX

New Member
update 2: FINALLY! IT'S WORKING!
so, I plugged this circuit into the outlet, and it started to create that high voltage, but the problem is that my computer immediately shut down. why? I think it's because I use a power strip where I have my computer, the monitor, the router, the cell phone charger, and the computer is the heaviest load, using a maximum of 200w, so when I connected my ballast that consumes 110w, I think there was not enough power for the power supply to work, and then the computer immediately shut down. in addition, the circuit created high voltage, but the voltage is so high that the pins started to create a very large arc, so what I'm going to do is isolate these pins very well and leave only the grounding pin exposed
 
Last edited:

RetroGamerCX

New Member
the problem is that because the output is direct current, the arcs are very noisy, if it were an ac flyback, the frequency would be so high that a normal human would not be able to hear. both ac and dc flyback have their advantages. the ac flyback can be less noisy because of the high frequency and it is possible to create plasma, and the dc flyback can charge capacitors and has a slightly higher voltage
 

RetroGamerCX

New Member
...but the voltage is so high that the pins started to create a very large arc, so what I'm going to do is isolate these pins very well and leave only the grounding pin exposed
well, but how am I going to do that? originally, I wanted to ground all the flyback pins, so that when the flyback started to arch, all of the charge on the pins would be discharged to the ground. the problem is that my house is not grounded and I don’t have enough wire to ground all those pins. so how can i prevent the flyback from arching to itself, both externally and internally?
 

Latest threads

EE World Online Articles

Loading
Top