Vestel 17IPS12 no backlights , fault finding to component level

A simple way to fault find to component level using a replacement board on a Vestel 17IPS12 power supply/backlight driver PCB .

[@Barbarapape]

Great piece of fault finding to component level. Very rare for a leaky ceramic capacitor to behave like a diode. In my experience, capacitors can cause very strange hard to find faults. Les Lawry-Johns tale of the blue tant springs to mind, now i am showing my age!

[@michaeldranfield7140]

I would imagine these caps give more trouble than we give them credit for but as most other manufactures don't supply service manuals most faults never get investigated and a new board is just fitted . I remember a red tant giving trouble in a Thorn 9000 chassis , I seem to remember it was C171 ? in the middle of the decoder pcb

[@Barbarapape]

@@michaeldranfield7140 Tant capacitors seemed to be a common source of trouble, fixing to component level is becoming a lost skill as all we can do is replace a faulty PCB.

[@michaeldranfield7140]

@@Barbarapape only a lost skill because manufactures no longer supply any circuit diagrams, that's the thing I like about vestel , old technology and diagrams still available for most stuff.

[@Grassland-Outpost]

Goes to prove the best instrument for repair work is the one between our ears. I would not have thought to reverse the meter leads when checking for leakage. Nicely done!

[@michaeldranfield7140]

yes , never fully rely on test equipment no matter how good it is .

[@kendom33]

Great fault finding Michael. Very few people can fault find to component level now as most just stick a board in !! Very instructional video. Thank you

[@michaeldranfield7140]

Virtually impossible in some sets but vestel still supply some diagrams .

[@dimitrismaster]

​@@michaeldranfield7140 Id hope they supplied firmware for their sets,so I won't have to trial and error what I find on forums here and there.

[@michaeldranfield7140]

@@dimitrismaster I have already spoke to a guy at vestel and he said they are not allowed to supply firmware because the rights are held by the brand holder , so in the case of Hitachi the brand holder is Argos and they don't supply firmware , there just a retailer .

[@dimitrismaster]

@michaeldranfield7140 Yeah it makes sense,unless you are an authorized service center for the brand,or for vestel in general.Or have connections with Turkish technicians.

[@xyredmax]

MLCC - Our new nemesis!

[@michaeldranfield7140]

I think you may well be right on that one

[@truthreigns7]

Welcome back Mr. Dranfield. I am glad you were able to get out of your house and down the road away from the snow.

[@michaeldranfield7140]

Couple of days later and its all melted, you would never have know it had snowed at all on Monday .

[@IrishvintageTVRadio]

Nice one Michael 👍 Great fault finding and nice to see the meter in action.

[@michaeldranfield7140]

Very useful that meter is and the fault makes no difference to me , I never use a meter vertically anyway , I have a Hansen meter with a higher ohms range but it uses a 22.5 volt battery that went out of production many moons ago ,

[@gjt2209]

Michael, thanks for passing on your wealth of knowledge through this channel. You break the information down and make it easy to understand, without the need for expensive test equipment. I'm going to blow the dust off my AVO 8, which I inherited as an apprentice.

[@michaeldranfield7140]

Only made possible as vestel still supply some circuit diagrams though.

[@OaklynHall]

Another excellent fault finding video - thank you for sharing it with us. Your fault finding skills are excellent.

[@michaeldranfield7140]

Many thanks for that .

[@darkobrankovic4979]

Hello Mr. Dranfield, this is Darko from Serbia considering that decca tv set type et 0862.Bloody hell I never manage to find out what chassis it uses. That information is missing somehow. But last time we were conversing you mentioned that you probably never had that type on your British market. Thinking of that You are absolutely correct. Not only that there is difference in supply voltage. but also tv standards between Yugoslavia of the day. now Serbia, were very different. if I am not mistaking....

[@michaeldranfield7140]

Yes but it could be similar to a chassis we had in the UK , if you had a photo I could see if it looks like anything we had over here .

[@whitesapphire5865]

A "capresisdiode"!! You should patent that as a universal electronic component! - One part for three jobs.

[@mistermikeanson]

🤣

[@ralphj4012]

thermicapresisdiode.

[@whitesapphire5865]

@@ralphj4012 Ah yes, that too. Well spotted on the fourth function. That wasn't meant to go public until six months after the release of the component itself...... 😚😸🤦💫💥🔥

[@michaeldranfield7140]

a bit like the vestel one board fits all approach !

[@whitesapphire5865]

@@michaeldranfield7140 That is one astute observation! I hadn't seen it that way before, but I reckon your about spot on!!

[@wisher21uk]

Michael you’re a star, very good find and thanks for the hot tip 😊

[@michaeldranfield7140]

Many thanks

[@Rollin-Rant]

I still use an old Avo, much more indicative than a new fangled digital device. 👍

[@michaeldranfield7140]

I find for tracing leaks in semiconductor junctions a analogue meter is essential .

[@jonathaneastwood2927]

@@michaeldranfield7140 Digital meters just wont keep still lol

[@coffdrops69]

Thanks for sharing your knowledge and fault finding tips. Invaluable information for those of us that work in this field.

[@michaeldranfield7140]

No problem at all , many thanks for watching .

[@coltronex]

Good piece of fault finding,well done!

[@michaeldranfield7140]

Many thanks .

[@Oldgamingfart]

Just when you think you've seen it all! Once again, some brilliant fault-finding. Also interesting to observe the lack of any handy test points to clip onto. Bit of an oversight there, from Vestel!

[@michaeldranfield7140]

Most Vestel design and even back to there CRT days is just lifted straight from the chip makers datasheet , its all pretty much bog standard, so if you cant find a service manual just download the chip datasheet.

[@michaelwaite6725]

Interesting that the suspect capacitors meter reading altered by applying heat I suppose it would be the same with freezer applied but that's not practical when the board is fitted in situ . The Eagle analogue meter helped show the variation wonder if a Avo meter would have been better . Good bit of detective work anyway Michael

[@michaeldranfield7140]

not sure why heat and cold affected a MLCC but that phenomenon could well have lead me down the wrong path if I had heated the pcb while it was still in the set . I dont know what resistance ranges the AVO has so cant say if it would have been better or not .

[@nigeljefferies8713]

Great stuff a true electronic detective. Regards Nigel

[@michaeldranfield7140]

Only made possible as vestel still supply some circuit diagrams .

[@karloflochalsh8817]

Special Chinese capacitor, gotta watch out for them :D. Component level all the way. Some sort of electrolysis between the plates accounting for the changing result?

[@michaeldranfield7140]

Don't know but it was very strange , might have to have a look on the internet and do some research into MLCC failure .

[@oldblokeh]

Most of these ceramic caps are piezoelectric to some extent. Maybe opposite voltages are causing deformation in opposite directions thus affecting the leakage?

[@matambale]

Brilliant, that was

[@michaeldranfield7140]

a very strange failure mode indeed but it had a much lower resistance until I unsoldered it , you would have never detected it in a comparison test in the very high resistance state.

[@skyoreece9805]

Well done, its hard to believe that little capacitor

[@michaeldranfield7140]

I have had MLCC caps give trouble before but they usually go short circuit so this was a new one on me .

[@whitesapphire5865]

I wonder how it would behave if you applied a known DC voltage across it, and measured the drop - I wonder if the drop would be the same both ways. Logically, I would not expect so.

[@michaeldranfield7140]

I still have the cap so I could try that .

[@robtitheridge9708]

I have a feeling thatfault would of beaten me excellent fault finding.

[@michaeldranfield7140]

Only made possible as vestel still supply some circuit diagrams .

[@andygozzo72]

i've had similar different readings with old wax paper dielectric caps...

[@michaeldranfield7140]

I'm going to do the same test with some old wax paper caps and see what happens , I have a feeling though they wont respond to temperature variations as the MLCC did ?

[@skyll4141]

I've had intermittent faults with those and gave up on the repair. You might have found the issue there.

[@michaeldranfield7140]

Something to remember for the future for me too.

[@adamdavies163]

A varidiode cap😉

[@michaeldranfield7140]

yes , I think these are going to be trouble

[@adamdavies163]

@@michaeldranfield7140 Do you think that's going to be a common failure mode? Most people would simply check the ceramic cap for a short and move on assuming it's fine. Fantastic find though, keep these vids coming.

[@michaeldranfield7140]

@@adamdavies163 I think its been a common fault for a long time but most sets just get a new board fitted because manufactures don't supply and service manuals or circuit diagram and there's not much hope of finding a fault like this without a circuit.

[@michaelturner4457]

This got me thinking of vestel virgins.

[@IrishvintageTVRadio]

Procal Harmon.... "She said there is no reason why my cap should be a resistor and a diode, and her face ghostly turned a whiter shade of pale....

[@michaeldranfield7140]

yes !

[@matambale]

That is a strange failure mode - as though the dielectric had some semiconductor contamination? Maybe? Love the tripod, quite a bargain that was.

[@michaeldranfield7140]

very strange, even more so under hot and cold temperatures , not had this before with MLCC s , looks to be quite well made the tripod, I bought one for more money than that in a discount store and it was crap so I never used it again .

[@ahmeddahmani2662]

merci et bon courage

[@michaeldranfield7140]

Many thanks for watching .

[@andygozzo72]

yep, i would wonder if it absorbed moisture from the air, i hate these surface mount things, i'm sure excessive miniaturisation is the problem , also maybe tin whiskers forming internally, i have similar leakage issues with an old pentium 1 pc motherboard, intermittent reset line dropping low enough for it to hold on reset

[@michaeldranfield7140]

you might want to try heating and cooling on your Pentium as it had a dramatic effect on my cap , this is something I have never seen before in a MLCC .

[@collegge423]

Michael thank you...Re vestel 17ips12 .Is a fluctuating voltage on HV pin 8 and VDD pin 6 correct.Also do you know how to power on the board without the main board,,Thank you again

[@Synthematix]

Maybe that small cap is holding a very tiny charge from the meter in one direction or the foil

[@michaeldranfield7140]

Maybe but the heating and cooling was a very odd phenomenon , I would expect that to happen with an electrolytic but not a MLCC.

[@Sctronic209]

Did you try shorting the cap each measurement.

[@michaeldranfield7140]

No as reversing the polarity would have caused the cap to discharge

[@Sctronic209]

@@michaeldranfield7140 a valid test would be discharge it each time you test it.

[@michaeldranfield7140]

@@Sctronic209 still got the cap so I will try again tomorrow but I don't think it will make any difference to the thermal test .

[@gonzinigonz]

Its like some weird galvanic type effect, especially being affected by heat.

[@michaeldranfield7140]

very strange and something I have not come across before , if I had tried heating and cooling with the board in the set it could well have led me down the wrong path .

[@gonzinigonz]

@@michaeldranfield7140 It is, its great if you can to spend the extra time to get to the bottom of weird faults though in the age of board swopping. Its what keeps it interesting like your channel :) I have come across the galvanic effect in the past but made sense once worked that bit out. Like you say it most likely moisture has got in there at some point.

[@michaeldranfield7140]

@@gonzinigonz given the low price of a new board a job like this would not have been economical to do and the sensible thing to do would have been to fit a new board but as you say this would not have made a very interesting video just fitting a new board .

[@samslots1234]

Very unusual behaviour by the diode,another reason I hate vestel sets!

[@michaeldranfield7140]

yes but at least vestel still supply some circuit diagrams, most manufactures don't supply any now , its board replacement only

[@GreenJimll]

So if a temperature dependent resistor is a thermistor, have you invented a "thermacitor"? 🙂

[@michaeldranfield7140]

yes !!!!!

[@minasmash]

i have 36 volt in led out but led not turned on tha cap and diod is working will no leakage so is not boosting voltage i think from the led driver do i need to replace it ? and what outage voltage do i need to read ?

[@michaeldranfield7140]

you would need a scope to check the output from the chip to the mosfet to see what the problem is .

[@phester28]

would this also show on an esr test

[@michaeldranfield7140]

no .

[@DrHouse-zs9eb]

1:30 what are you talking about? Increase the output? 😅 You probably mean that it's a boost converter increasing the voltage for the LEDs. This Video helps nobody with that lack of explanation.

[@thecyborg6718]

You should buy a digital multimeter that measure capacitance to make your life easyer