Tv flyback transformer making a ticking noise and tv won't turn on - Page 1
Forum section: electronics / repair

author: Ravichandran
author_rank: Contributor
timestamp: June 24, 2018, 09:20:43 am
content: Hi guys,I had an old tv which doesn't turn on the display. Also the flyback transformer was making a small smoke. Then i replaced the flyback transformer with a new one and the tv worked fine for few minutes. Then suddenly the tv turned of and the flyback transformer started to make a ticking noise. Still the problem is same. Can you guys help me with finding the problem?

author: jjohannes
author_rank: Newbie
timestamp: June 24, 2018, 02:06:15 pm
content: I'm no TV repair expert, but it sounds to me like you have a short in your flyback. I recommend taking a look at the Sam's Repair FAQ site, it has loads of info on fixing TV:s and has helped me a lot in the past! For instance:https://www.repairfaq.org/REPAIR/F_flytest.html

author: james_s
author_rank: Super Contributor
timestamp: June 24, 2018, 04:08:55 pm
content: I would start by looking for shorted semiconductors near the flyback, particularly diodes that rectify the various outputs. Check the soldering on the horizontal drive transformer, and if you have an oscilloscope you should check the horizontal drive waveform. Keep in mind many TVs use a "hot chassis" design so an isolation transformer is needed.

author: stj
author_rank: Super Contributor
timestamp: June 25, 2018, 02:10:36 am
content: check the flyback transistor and all the diodes & electrolytics on the accillary windings for shorts.

author: andy2000
author_rank: Frequent Contributor
timestamp: June 25, 2018, 03:06:24 pm
content: Is the replacement flyback a genuine part, or a generic replacement? I have seen generic flybacks fail to work out of the box, or fail shortly after installation.

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 25, 2018, 08:32:22 pm
content: Here's a guy with ton's of experience repairing TV'shttps://www.youtube.com/user/ATVVideoProductions/search?query=crt+tv

author: Ravichandran
author_rank: Contributor
timestamp: June 26, 2018, 06:32:35 am
content: it was a generic replacement.

author: Ravichandran
author_rank: Contributor
timestamp: June 26, 2018, 07:18:58 am
content: Also i found out that the horizontal output transistor has burnt.

author: james_s
author_rank: Super Contributor
timestamp: June 26, 2018, 04:30:30 pm
content: That's a fairly common problem. It can be caused by a bad flyback but other problems in the circuit can make it fail too. The horizontal section is a resonant circuit so everything has to be just right or it smokes.

author: Ravichandran
author_rank: Contributor
timestamp: June 28, 2018, 03:15:29 am
content: I replaced the failed HOT with a new one and turned on the tv. Then the screen was lighten up for about a minute and suddenly turned off. Then i checked again the HOT and it also has burnt and it was like really hot. What could be the problem? Is it a problem with the replaced flyback or any other component?

author: james_s
author_rank: Super Contributor
timestamp: June 28, 2018, 03:33:51 am
content: It could be the flyback, or it could be the drive waveform, or it could be something wrong with one of the other circuits powered by the flyback. Usually there are a few diodes that rectify other outputs, if one of them shorts it can cause the horizontal output to fail.

author: andy2000
author_rank: Frequent Contributor
timestamp: June 28, 2018, 08:17:20 pm
content: It's hard to be very specific without a brand and model number, but I would guess you got a defective replacement flyback. A short on the secondary will usually just cause the set to shut down.The fact that the HOT didn't fail until you replaced the flyback also points to the new flyback as the problem.

author: Relayer
author_rank: Contributor
timestamp: July 02, 2018, 01:11:28 am
content: Hello Ravichandran,What is the make and model of the telly?Regards,Relayer

author: envisionelec
author_rank: Frequent Contributor
timestamp: July 02, 2018, 02:10:36 pm
content: It's been a few decades since I've repaired a television, but I can tell you that you need to replace the HOT, the flyback, the big blocking diode and the big HV capacitor. Or you'll see this failure repeat itself.Good luck!

author: Ravichandran
author_rank: Contributor
timestamp: July 03, 2018, 08:42:49 am
content: My tv model is samsung CS-21Z57ML. Can anyone help me with checking the condition of the flyback transformer which i replaced? Yeah the old HOT was good until i replace the new flyback.

author: james_s
author_rank: Super Contributor
timestamp: July 03, 2018, 05:12:30 pm
content: Flyback transformers are difficult to conclusively test. I have a ring tester that has been helpful, I think I still have the schematic somewhere, it's not a very complex circuit. You could also build a simple flyback driver with a 555 and power mosfet, but none of these are the same as operating it in circuit.

author: stj
author_rank: Super Contributor
timestamp: July 03, 2018, 05:54:44 pm
content: you should start by removing the drive transistor and hooking a 60w mains lamp across the B+ line.that's the supply to the transformer via the transistor.it should be a stable dc voltage between 80 and 120v dc.there will be an electrolytic smoothing cap across it that makes it easy to find and solder to.

author: Ravichandran
author_rank: Contributor
timestamp: July 21, 2018, 06:12:33 am
content: Hey guys, I replaced the flyback and HOT. The high voltage capacitor was in good condition. Now i can hear the sound of channels. But it only displays an ash color screen. I can't even see the program menu or volume up and down bar in the screen. What will be the problem now?

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2018, 06:36:08 am
content: What do you mean by an ash color screen? So the tube is lighting up? Did you try adjusting the Screen control on the new flyback?

author: Ravichandran
author_rank: Contributor
timestamp: July 21, 2018, 07:15:23 am
content: Yeah, the tube is lighting up. No i didn't adjust the screen control on new flyback. How can i do it? Appreciate your concern because i am not an expert on TV repairing.

author: stj
author_rank: Super Contributor
timestamp: July 21, 2018, 12:00:19 pm
content: most transformers have 2 controls on them,screen - which effects brightness,and focus.always ajust screen first, because it effects the focus.

author: Ravichandran
author_rank: Contributor
timestamp: July 21, 2018, 12:17:26 pm
content: Ok.i adjusted those two screws and i was able to make it working. But the tv worked only for about 20 minutes and i turned it off. Then after few minutes i tried to turn it on and it didn't work. So i checked the HOT and that transistor has blown again. When the tv was working, i noticed an excessive heat in the hot also. What will be the reason for HOT to blow again?

author: PKTKS
author_rank: Super Contributor
timestamp: July 21, 2018, 01:51:35 pm
content: My friend I have done this for a considerable long period of time.This is probably the top item on CRT fail list.It is not possible to guess - really - the causes are just too many.My routine to track down the issue may help you organize yours:- First and foremost - the flyback itself is like any other SMPS . Ditto- The thing starts to be different (SMPS) in that it works at 15KH mostly- And.. there are 2 main targets on that flyback "topology"- The main target is always the EHT to the tube - that is rarely the issue- may be .. but rarely is. The current is low and chances to cause a failure are just overheat- The second target of the flyback is the secondary power to several stages.- CRT Flybacks evolved from discrete components to integrated ICs (controllers)- Nevertheless the secondary side is likely to have discrete regulators or just zeners- THESE SECONDARY REGULATORS are very frequently the problem.- Leaking caps or dead shorts may overload the primary causing the power switch to blown or overheatThe methods are tedious:- Disconnect all secondary loads- TURN YOUR CRT SMPS BY USING A VARIAC - ** IT MUST BE PTC PROTECTED **- Please google for "VARIAC INCANDESCENT BULB" and check that - THIS IS REQUIRED- Powering the SMPS by VARIAC BULB you can prevent the switch to blow.- You will connect each secondary regulator in steps to have certain they are not overloaded.- Until you have the SMPS properly working on both sides.The method REQUIRES the VARIAC BULB and the STEP secondary loads.Eventually you will detect .. a dead short or leaking CAP which is overloading the primaryThe cost of a new Flyback and/or new power switch justifies all care in powering by VARIAC BULBhope helpsPaul