Here we have another useful fault finding tip on LCD tv sets .
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- Опубликовано: 10 июл 2024
- Yet another common fault on flat screen TV sets is presented in this video as most manufactures now do not supply service manuals , fault finding to component level does not exist any longer , and board replacement is the official take on repairs, however new boards are expensive so this tip may help you with a repair . Michael Dranfield .
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Fantastic tip. You're jogging my fault finding memory now. Thanks, great video.
sometimes I find myself forgetting things , especially when its not something you are doing every day .
As well as electrolytic capacitors for decoupling, I tend to add ceramic capacitors on the output of linear regulators. Ceramic caps have better high frequency characteristics. Nice to know that there are still people around who can fault find down to component level.
Unfortunately component level fault finding is getting a thing of the past, no service manuals now for most sets so and component level finding is more good luck than knowing what your doing .
Your knowledge is very impressive. Thanks for sharing!!!
Many thanks for that .
Good video problem is if the TV is for a customer,caps are cheap, labour and everything lol... very educational thanks for your time sir....
Many thanks for watching .
Michael, your channel is awesome!
Many thanks for that.
I remember the budget alternative to freeze spray used to be a can of air duster held upside down! :'D
that is something I have never tried as yet .
I buy cans of chewing gum remover now. It's the only thing I can get locally, and the price isn't bad. Probably better than actual freeze spray!
@@sw6188 Good call!
I have Hever tried anything but the real thing but worth thinking about if it's so much cheaper.
@@michaeldranfield7140 Airduster held upside down works a treat (they even have a greater freeze effect as the output is much greater!), although the cans of air duster are more expensive for me!
Thanks Michael for your time excellent.
Biggest tip for me - that the tab was the output on these regs!
its not the same in all regulators though .
Excellent tip. Thanks.
No problem , thanks for watching .
Thank you Michael another great peace of advice
Thankyou for watching .
Nice one MD I would have thought 1.2 v it is ok then would said it is BER as the price of these Currys own brand tv`s are so low they are disposable. keep up the good work ( glad I am retired my last job was repairing valve amps , the last TV I repaired must have been 15 years ago.)
it is an old set and belongs to a lady in her 80s who is very reluctant to get rid of it, last time I repaired this was just over 10 years ago but when this was new sets were a lot better made and backlighting was CCFL so much longer backlight life , might do another valve video soon ! many thanks for watching
This is very interesting video for me , person who do such repairs on the daily basis. But you know what I had so many PC monitors and TV's with such fault and what I do I just replace 4-10 capacitors which are know to give such fault and always, but always it fix problems, and actually never think about what happening in circuit because of one or more faulty capacitors. This is first time ever that I watched video on RUclips about electronic repairs and that I did not know thing about what video is. Huge thank you and YES you got me , I follow you and truly want to see more from you. Amazin video !!!
Should have more videos coming in the future, many thanks for watching.
Another useful gem - thanks MD
Many thanks for watching.
This is an eye opener for me. What rubbish cheap components they put in consumer electronics?
This is quite an old set so by modern standards this has had a good life even though it only has cheap parts fitted.
That probably also explains the "It was working fine last night" scenario, where the set cools down and that cap has had its last fling?
Could also be why so many people buy a new telly during the winter months?
same goes for something stood in stand by for years and then there's a power cut and the equipment wont come back on again .
@@michaeldranfield7140 Agreed 100%... I had exactly that with an early '90s Sony "High Black Trinitron". That set was rarely ever switched off at the socket, or its own switch on the front panel. It did start playing up for a while before it failed completely, but in the end it was a power failure that saw it go off for the last time. After that, it wouldn't turn on again, until the PSU had a couple of new electrolytic capacitors installed.
@@michaeldranfield7140 Good point, I'd have just assumed a power spike on the returning mains supply had killed something. (EG two routers went this way, two since the phone company want them back to replace them, I didn't examine.)
Always good to look much deeper, as you always do.
Great video. Very useful tip. Thanks.
no problem , many thanks for watching .
Thank you sir very useful tip
Many thanks for that .
Another great video - thanks for sharing!
No problem, thank you for watching.
If I'm not wrong then you can check these LDO voltages with your multimeter AC voltage range after you checked them with their DC voltage range. If there is ripples in voltages your multimeter AC voltage will show some higher mili volts ac or approximately more than a volt ac. I have also Fluke multimeter but my one is 87-V true rms multimeter. I use this technique or simply check with my scopemeter too for ripples in DC voltages rails.
Ypu could be right but I prefer to check with an oscilloscope, you don't need one as expensive as mine you can get a Chinese one now for less than £200.
you cant always measure an ac voltage riding on a dc voltage, many meters wont allow it or give correct readings, you have to check its user manual, or set to ac volts and try to measure a 9v pp3 battery, if you get any reading other than zero, within a a few mv, its not suitable, but you can sometimes use it if you use a dc blocking capacitor in series
@@andygozzo72 this is true but with the price of a cheap oscilloscope these days I dont think many people now wont have a cheap scope .
Very InTeReStiNg!
Many thanks for watching .
You are a brilliant tech
Growing up I would see on a schematic small cap values near a semiconductor device and think
"that isn't going to do/help anything", and would just leave it out.
Now we know, high frequency "noise".
Correct.
Very interesting , thankyou for sharing
Thank you for watching.
Very useful and interesting Michael. I have no scope so thank you for the tip. I have a Sony LCD Tv and I am hoping some new earthing bolts which were missing on the power supply will cure my TV switching off after a time
May be, there is one particular Samsung TV that trips out intermittently due to a loose earthing screw on the inverter board.
@@michaeldranfield7140 Thank you very much I will check the inverter board more carefully tomorrow ☺
Hi again Michael I still have that Sony LCD and i am back again with the inverter board to try overide the protection causing the set to go into standby and 4 blinks. There is only the one IC on this Kdl 32v4000 and pin 4 jumps to 24 volts when on back to 5 when off.If you have one of these type repairs i will be delighted to see☺
@@walker55able you need to get the datasheet for the driver chip on the inverter, from this it will be possible to disable the different protection circuits so you can see what's tripping the protection, I seem to remember though on some sonys its just a loose earthing screw on the inverter board ?
actually something else has just come back to me now the inverter transformers suffer from an intermittent change in secondary resistance and this will cause the inverter to trip out , check the secondary of each transformer for its resistance reading both when its hot and cold .
Funny how at the beginning, I thought it was going to be a video about SMD voltage regulators but in the end, it’s yet another video about the usual culprits - CAPS!
Nice Info
Thanks for watching.
A Dixon's special. Suprised it left the shop working.
We use to think that about Matsui and Saisho branded sets in the 90s.
@@michaeldranfield7140 made in same factory often some of the products like their TV's were identical and had same model number or at least partly same number, and only the badge was different with the 2 versions of the same product was sold in different stores eg Currys had one brand, Dixon's the other. They now have loads of other brands and the corner cutting is worse, but they still sell them at a premium, eg Logik stuff is just rebadged kit not sold in the UK under other brand names, made to the bare minimum spec required for safety and AFR. It's funny how they are the only retail store like it left in most of the country and instead of trying to keep standards high they are doing a Maplin instead, price gouging, treating staff like robots, jumping on customers the second they enter as if they were shoplifters and pressure selling at every chance. I buy from China direct now, at least I know what I'm getting, the price is more appropriate for the item, and no hard sell!
Michael can you advise please just had to use the light bulb test as another LCD TV that i restored went down last night. The light bulb comes on then pulses on and off approx every second. I guess i need to replace the power supply. Thank you
I have the older ESR60. I have added a foot-switch for easier operation.
Have one of those as well, I know Jeremy that makes these, he's only 5 mins down the road from me on the same industrial estate.
looks like that is the cold side of the power supply, have to be careful as you probably know on the hot side of the power supply using a scope.
All my benches are powered from isolation transformers so I can scope the hot side no problem .
bravo prof like
glad you liked the video .
The explanation of the issue itself was great, but the explanation of how to use the hairdryer was confusing. So you heat them up when the TV is connected and the back cover is off and see if it turns on? Or you apply heat while measuring with something cheaper like a multimeter? I'm confused.
When an electrolytic capacitor is cold and worn out its value falls and ESR increases however if you try this with a good electrolytic it will remain more or less the same regardless of heat or cold.
Hello Michael, I am very interested in the transistor replacement for guitar tube amplifiers, I would love to talk to you about it!
love your fleece lined jacket.
I have had to turn the central heating off, the heating oil has risen in price from just under 30p a litre to over £1.34 a litre and it's still rising, hence the coat!!
£20 for spray freeze, wow its “under” £10 in Australia
Problem is here in the UK the post office banned the transportation of aerosols amongst many other things so you have to have these delivered by courier service which puts up the cost .
I wonder if you could know what ghosting could be a result of ?, Thank you.
Picture faults are usually down to a fault on the LCD panel itself.
Nice video have you shown the circuit of your esr meter ??
No, I didn't design this, I only made it, it was more than 20 years ago though, It came from the magazine I use to write for, Television magazine, I think it was on one of the 1999 issues.
Thank you Michael I think I have found a circuit in a electronics magazine
I will look in old tv mags
Cheers Peter..
Let me know tomorrow if you can't find it and I will have a look to see if I can find which one it appeared in.
The Television service mag was the march 1999 for the E.S.R meter
@@littlebear5219 A pretty good guess of mine then !
I have a sharp LCD tv. i think its a 60 or 65. it used to work then quit. TV powers on, has sound, the LCD panel lights up, but theres no picture. Not even the OSD. I thought it was a backlight issue but no, the panel actually lights up but I cant see anything, no OSD and no sharp logo or picture. Was thinking a bad mainboard?
Fault you describe is more likely due to the LCD panel or Tcon board than main board, a very common fault in a lot of sets is failure of the surface mounted fuse on the T con board, check it has 12 volts on it, if it doesn't then it could be the main board.
@@michaeldranfield7140 okay I'll pull it apart one day and have a look at the fuse. If it is the tcon I'll replace it but if it's the panel it goes to scrap. Too much for a panel
As that's a known fault and the price of the spray, I think I would take a chance on the price of 2 electrolytics.
Since the post put a restriction on what you can send aerosols now have to be delivered by courier service which has increased all service aids prices unfortunately .
Could you measure the ripple with a meter set to AC volts?
Well, it's not a bad idea but most meters don't have a bandwidth of 10MHz so you would get a wrong reading.
I would think it would be a good try. I used that technique to show the voltage at a CPU in a loptop that worked on battery but not AC because of bad tantalum caps at CPU. Ripple voltage showed when AC but not on battery operation. But either way, if the heating cooling trick, didn't show anything not many are bothering with oscilloscope testing after MM shows correct voltages. All depends how important the repair is and TVs so cheap nowadays. Ok, I'm back to my time machine project.
Where is Grommet?
That is just bad design those caps will just fail again any application data on 3 terminal regulators will show other low value non electrolytic caps. across those to decouple high frequencies and to stop self oscillation elecros. are only good on less than 100 khz in my opinion
now were on the just as un reliable MLCC capacitors for decoupling 3 terminal regulators !