You just earned my subscription. I had a repair shop for around 10 years in the 90's and then moved my career to the aerospace. I miss some of the challenges I had those days.
Great video!! I got the famous samsung TV with the bad caps years ago for free and at the time it was just the caps. Replaced them and viola! Great TV about 4 years later got the clicking on and off and thought it was bad caps again. Was not. Spent a month chasing it down to believing it was the power board but I was getting a pulsing on off power on the standby wire. Spent some time and came across a mention on the video board about some components around Capacitor C102 with the IC regulator next to it. The fix was to replace the SMD cap and the regulator. I opted to just touch up the solder on the board and add a 10uf cap onto C102 and tv works great again. I thought it was a bad CCFL tube as the set reports over 120,000 hours. Tv still works great. Better picture than some of the LED tvs of the time. I'll watch this video again if I have more troubles. Thanks for the video.
Also the faulty lamp can be disconnected from the pcb and solder as a dummy load a capacitor in the range of picofarad from 22pf to 220pf 3KV.The value can be found experimental,a small capacitor means disconnected lamp,a large one shortcircuited lamp.So something between the two ranges.
Good Vid. Had one, but after jumping across the transformer the picture stayed on but the BL was flashing. Removing the entire transformer cured the problem. Thanks.
I'm a complete electronics noob and even i intuitively understood the issue and how it was solved. Nicely explained. I'd have probably struggled without the hand drawn diagram though.
Nice Video. It would be interesting to see how long a stop-gap solution like this works, since the remaining 11 transformers now see almost 10% more drive (also the remaining tubes..). When a tube fails, AFAIR it can't establish an arc, so it goes Hi-Z, this means more feedback voltage (again an FB on the diodes) so it may be healthier in the end to short the tiny sense winding or do a quick knife-cut on the trace to the diode.
You earned a subscriber for a great video and good explanation I like your pencil diagram of the wiring. If this noob understand what you did, perhaps a penciled in pin 1 for input and penciled in pin 3 for out for the primary would have helped. Or also putting that caption you added in your video a few second later on to your diagram, would have also been helpful, for me. Also a penciled in pin 2 for ground and penciled in pin 4 to diode, would have been advantageous to this noob. If I am understanding this correctly; when you soldered a pin to pin 4 and then putting a jumper wire from pin 4 to ground you basically took the diode out of circuit or you basically took the monitoring side, out of circuit. Therefore, no shut down since the monitoring side is out of circuit. When you soldered a jumper wire from pin 1 to pin 3, you are basically taking the primary for that particular light out of circuit or the wire then acts just like putting that particular winding in serious by bypassing it. As an alternative could you have soldered a wire from pin 2 to pin 4, I am assuming pin 2 is the ground from you diagram, which would have taken the monitoring side out of circuit and it would leave the primary still in circuit. Perhaps best to take primary out of circuit to avoid future potential overheating, smoke, etc. Sorry, lots of wondering from a Noob. But, I am sure you made this video for us Noobs, not the professional.
Excellent video as always. But wouldn't be better to measure the dropping voltage across one of the transformers and then calculate and put a resistor, which will result in the same voltage drop as in the other transformers? Now you will have slightly increase voltage in the working transformers, so more stress to the working lamps.
Greatly enjoyed. I could watch 100 such vids to learn more. I'm not a repair technician but have some electronics background, would love to repair my Samsung tv. We recently had town power outtage. Once power returned, I figure a surge killed the tv. Black screen except for a very dim overall lighting, no sound. Some of these power supply boards have fuses, but mine doesn't. Why no fuse? Watching several repair vids, it seems like the problem could have several causes. If power surge caused this, what is the most likely problem? Thank you so much. Would love to learn more.
I had a funny one trying to fix like this. The lamps came on for a second, something in one of the lamps or the transformers would audibly buzz, then it would shut the lamps off. So I'm going through all the sense lines, grounding each one as I power on the tv, as you were doing, and then grounding one of them the lamps stay on, but then the buzzing sound would change pitch, ALL the lamps would dim and flicker, then it would stay on, or run a while and shut off. Then other ones would make the lamps stay on, then after I grounded all of them one at a time, the TV stays on and I can hardly hear a buzz. I'd found and replaces a few bad caps in the power supply earlier, maybe the bad caps were leaking some kind of charge into the sensing system and it all had to be discharged. All the lamps seem fine now, weird.
Interesting video, thanks. Next show us how to prevent a power supply from shutting down or toggling on/off all backlights when you have one or more bad LEDS on a backlight strip in a LED Backlit type Television 😁👍. These strips can be a pain to replace.
How much trouble and expense is the tube replacement? I've got a question. When you see a line across the screen or maybe two or three, what causes this? I've seen where people discard them because of this problem or give the sets away. enjoyed this session very much. One television repairman in a very small town called Rendon Texas, acted like the New LEDS were not repairable. I know the Plasmas were a big problem. Didn't take long for them to disappear. Thanks for the the video. I noticed that with time, you have gotten better and better with your presentations. I was watching one from 2014 and big difference. Tally Ho...keep up the great work.
I replaced a tube in a laptop once. I was very proud of myself but it only lasted about a year, so it's not worth spending the time and money (£10 for the tube) again for that old machine. I've got 2 LCD screens with multiple tubes, that won't turn on because I presume a single tube is dead. I'm either going to transplant a tube to give one a full complement, or fit a ballast in place of the dead tubes. It's fiddly work peeling the panel apart, but when you get down to it, it's just 2 solder joints to fit a new tube. I've considered making a long, thin pcb with white LEDs to replace the laptop tube, but that's probably more work than it's worth unless I sell them.
Have I mentioned how much I like your channel? You provide valuable information every episode. Sometimes I check your channel to see if you've uploaded a video.
Nice work. I have a set right now I'm working on for someone that has a bad CCFL bulb. Since he's paying for the fix I'm going to order a bulb and pray that it makes it in on piece, as I've never had one shipped to me before. They are cheap so it wouldn't be a huge loss. I really don't want to bypass the transformer or the protection circuit, but I did think about it.
Bypassing the lamp is very common in the repair industry. Everyone I know in the business bypasses lamps because of the hassle and potential damage to the screen or tabs tearing it apart. If a screen only had 4 lamps, then if you bypass you will definitely see it on the screen. With 12 lamps it is barely noticeable unless you are staring at a static screen. On moving images this is not even detectable to the eye.
Yeah, that's true. I've already torn the tv down to get access to bulbs though, took me maybe 20 mins (I'm used to doing it to tvs at this point.) Might as well just wait for the bulbs to get here. I have spare bulbs, just not for a 42" at the moment. Also, my parents just had me fix their 55" LED Hitachi a few weeks ago, the thing was a YEAR old. It wouldn't start, the output to the LED backlight was really high voltage, so I had to check the LEDs. Tore it apart, sure enough, one was blown. I bypassed it with a 1N4148 and slapped it back together, runs fine. Do I notice that one little dark spot? Yeah, but nobody else does lol. So you are right, it would just annoy me if I knew it was there.
Understandable, I am tired of tearing them apart too, overdriven backlights are just causing so many failures. I meant to ask about your scope also but I see you haven't had any luck yet from the other comment
Hi there! What if you solder a variable resistor between the transformer and lamp to find out the limitation current. As I may envisage (correct me if I'm wrong) the lamp current limitation may lower the values which appear to be shut down the TV. The light could become dimmer or blank totally. But who knows? May be it's still enough to cast some light and reduce the shadowing on the screen. If I got your situation right the lamp tube cathode voltage was rising. So I may assume that the faulty lamp resistance is lower than the rest, and it appears to be the reason. Don't take it as an "enlightened teaching" coming out to you from the sky. I'm just curious if I'm able to solve a similar issue myself. But I suggest to figure the highest voltage value that the lamp power consumption produces with the protection bypass, not for too long of course. And in case it won't get any higher than the values you've already known I would try this approach.
I have almost this same TV, but it doesn't light up AT ALL. I tried measuring Vac between ground and the high-voltage terminals, but got 100mv or so on each. My friend thinks my meter just can't read voltage at "that high of a frequency" and suggests the tubes are at fault anyway. I don't think the tubes would all die at the same time. My money's on replacing the power board. What do you think? More info: I do see the picture using a flashlight, audio does play, no blown caps. One day AFTER it stopped working, I had left it "on" for a long time, and it suddenly started flashing the picture at a short, regular interval for a few minutes, then went back to black. I haven't seen that since. Thanks for any time you can spare!
I'm starting to think this could be my problem on this LN46B550K I have. Got this and a LN40A550 from a dumpster month or so back, 40" was an obvious fix with 2 "bulgers" on PSB (2006-8 counterfeit caps scam) Still going strong ;) the 46" had a blown thermistor and fuse, powered up ok after replacing. Then starting couple weeks ago, it had that bright to dim fast flicker to it after power up, but would eventually mellow out (not full brightness, but watchable) If I went in user menu and tried to adjust backlight strength, it would start doing the fast bright to dim flicker again, eventually stopping. So now I go into service menu and see that it has almost 11,000 hours on it. (Note: I had a firmware upgrade for it from Samsung and did that as well, although after upgrade, hours went to 0 and the purchase date was the day of the update 12/13/2017...lol) As of yesterday, now when I power up, picture comes on in flashes, 4 times @ 1 sec intervals, then goes black (Audio still there). I'm assuming current sense shutdown in process because I get no AC from source supply after it goes black I havent peeled the screen back to see the ccfl's, but I'm imagining that they're pretty blackened by now. If this IS the problem, I'm wondering if I can convert to LED??, I'm sort of like you 12v, I have a vast graveyard of panel carcuss's, just don't have any ccfl's that would fit a 46", but LED's on the other hand.... ;) Thanks as always, ~Malfunction Junction
nice video, I learned a lot. have you had any luck finding a tripler for your scope. I bet it's like an old friend. I was offered a second hand scope when mine broke which was nice but I don't like having a broken one in the corner. ..sooner put it back to use. .don't like waste!
I have an Aiwa home stereo that I bought in the early 1990's. The double cassette deck broke. Do you know I can get them fixed? Everything else works fine.
this set is pain to fix,have one similar problem where mine took days to show up , went the extra step and replace four back lights,one was bad and the rest was not to bad and now is it works until it get bright it shuts down. joy o joy .
A little bit off-topic, and asking for your opinion/help. I have the same Power board as shown here BN44-00340A on my LE40C650L1W. The set won´t turn on at all. I got it from a friend. His son said it made a bang and smoked. I found the ceramic capacitor "CI831" blown. = F223Z 1kV = 22nF -20% to +80% @1000V It sit´s between the "-" Bus of "BD801S" = TS6B05G Bridge Rectifier and the drain pin of "MI801S" = FDPF12N50UT N-Channel MOSFET 500V 10A What could cause that damage? Overvoltage through lightning, or a defect in circuitry before/after the capacitor? I will change the HV Capacitor anyway and try it, but i would like to learn more about the development of such failures. When changing the cap, does it make sense to put in one with a higher voltage reading like 2kV than the original with 1kV ? Thanks
What kind of voltage are you getting from power supply to backlight inverter? I have the same tv in a 52 inch. Replaced the inverter board and nothing happened 😒
Got one now doing the same thing. it will come on and then power off after the Sony image. Going to try bypassing. Since this is an older TV and not many parts available.
Hi many thanx I've taken out all that glue stuff around my micro feral capacitors and soldered in New ones in my amp the old ones were budged up I'm Jess from Helland in Cornwall in the UK. Great videos can you mention this me many thanx.
Hello, I am troubleshooting with my Samsung LE40C530F1W TV. i have issue the TV doesn't start every times, but sometimes if start the startup sound apeared and It works properely till off. I can't find motherboard scheme, and even SPI to write bios again. Could You help me? What kind of damage is it? Thanks
Awesome video. Awesome explanation. One question, how do those lamps draw high current? They short circuit or something? Is it a sign of iminent death? Lets hope my message makes sense.
Fluorescent lamps are high impedance before they strike, and then the impedance drops to almost 0, and that is why they need a ballast as that is what limits the current.
Nice job.. explained well. Bypassing that transformer that way would cause a slight increase in primary voltage to the rest of the ones in that series, correct? Negligible I'm sure, as this would vary with brightness setting anyway.
The lamp brightness may increase slightly, but since the panel modulates the lights with the video content it won't be noticeable and for those that are concerned about a slight over power, the solution is just turn the back light control down slightly. One should never run the back lights at 100% anyway on either CCFL or LED, unless you want the lights to burn out prematurely.
Great video! I have this exact same TV with the exact same problem, however, here's a twist - my screen lights only turn off in this way when the temperature in my house is on the cool side - say below 68 degrees F! Doesn't seem to be a problem when it's warmer than that! As such, it is more a winter issue... Any idea what might cause such a temperature dependency? I may tear it apart and try your troubleshooting next time I forget to load the woodstove. Haha.
I have a Philips 42 inch tv about 10 years old. Its always had this problem: It sporadically turns itself on but has no sound, and the screen is white, then it will turn itself off again. Sometimes, I have to manually press the on/off button to turn it off. We had tech support replace the computer and power boards about 8-9 years ago, but this never really fixed this anomaly. Am I thinking the problem is not on the boards?
I have a Samsung LN46C530 TV exhibiting the exact same problems...did the test on backlight inverter board as you described and found that grounding the sense pin on 2nd xfmr from bottom of board made the backlight stay on. Then I did the jumpers from pin 1 to 3 on that xfmr and the set ran for about 30 mins...beautiful picture. But then backlight went off again ....still have audio and vol up/down and ch up/down are working. What do you suggest now ????? Could I have caused another CCFL to fail ?
Great video. I have the same tv keeps flickering and switches backlight off. Changed inverter but still same but I noticed after watching your video there's a tube out. Would bypassing the transformer for the dead tube stop the flickering and switching off? Don't really want to give up on it yet.
Now that was an odd one, i dont tend to mess with backlighting systems as its not allways obvious whats wrong. The high voltage and high impedence tube drive is something i dont have the equipment to check, i also know my limits lol. Well as you are the customer, you should complain to yourself about the bodge, try writing a angry letter to you, you may get it free, worth a try :-D lol.
I made a 100Meg probe for testing 35kv tv anode caps, it connected to my old digital of 10meg and divided by 100, perhaps that may be usable again for hv. Did you get anywhere with sourcing a ht box for your scope, that old heap must be horrible to use ;-(
No luck sourcing the x12 multiplier for the scope yet. No luck finding a scope at ham radio flea market. As you will see when I publish the 4K video of the event later today it was all old junk there.
Dam!, if your anything like me, you get used to the way certain bits of test equipment can be used for the best effect, i would be lost if i was in your place. Ham rallys often sound good, but are filled with overpriced crap :-(
Stephen Low the problem with replacing 1 tube is now there is 1 tube that is much brighter than the other 11 and 1 bright tube sticks out like a sore thumb. Much more noticeable than 1 dead tube that does not show off camera. I had someone over last night donating a TV and he couldn't tell where the darker spot was but on camera it shows up easily. to the eye not so much even looking at color bars.
I have a 40" Samsung LCD. I have sound but no picture. I can see images with the flashlight test. I have replaced both the backlight inverter board and the power supply board and still not working. The back lights flash for only a second when tv is turned on then they go off. Any help is appreciated. Thanks
Ser A have some problem with this model tv I checked and find some wrong. Blacklight not working, i checked pin 4 in transformer is 00.4 mV DC and 0.015V AC Im checked pin 1 in transformer is 3v The mosfet in power boad not working maybe protected by the protec circuit Please help me, show to me how to fix this problem Thanks you very much for your help!
Hello, I would like to know if you can help me, I have a Samsung LCD TV Series 3 Model LN32A330J1. It has 12 Transformers and 12 Mosfet 4614, similar to 40014A01. The fuse of the inverter card was damaged, and also the third moset from the bottom up. There is a possibility that I can eliminate that simply mosfet and also that ccfl tube. I think that only 1 ccfl tube of the 12 will not influence the lighting so much. Thanks in advance with the help you can give me
Made in Tijuana Mexico? I doubt it, perhaps that label should say "ASSEMBLED IN MEXICO WITH KOREAN AND CHINESE PARTS TO EVADE TAXES. Here in Mexico neither a screw washer is manufactured.
That set has nothing in it 😮....boy now there is no boards in These things now....the ATSC3 change over will put these out of order...they will only be good for Blu-ray player and Internet...
I have a 70” sharp I have sound But no picture I can see the image with a flashlight after about less than a minute the TV shuts off goes black? Any help would be most appreciated!!!
Loose ground screws also cause all sorth of weird problems. In this case it was a bad lamp, and even though I erred in the schematic for the "drive" circuit, the primary winding is used the modulate the secondary to control the brightness, by placing a jumper across the primary as I did I effectly shut down the bad lamp so it wasn't drawing excessive current. I have since pulled that transformer to get the dead lamp completely out of circuit as I don't need it coming back to nite me in the ass. The jumper I placed is required as without it, all the lamps will be running very dim indeed, as the control windings are all in series. So anyone doing this needs to not only put the jumper in, but remove the transformer completely.
Hi, What do you suggest for the following problem iam facing: I have the powerboard BN4400932B of a Samsung TV, which says the Standby power to be 11.8V. I disconnected the board off TV and checked the Standby power to be ok I.e. about 11V, when I connect the board on the TV the Standby power drops to 4.5V. What could be the reason?
Yes I did but the new lamp from before the television came on after then after I pay for some time then it stopped then when I put it in and put it back on it just blink red continuously
Sometimes i wish he did highres teardown photos of the set. I got a simular model as that one exept mine takes 2-3min to actualy power on and show a picture or play sound. So i'm thinking there is something realy simple wrong with it coz once it's on it works fine.
