LCD repair education.

[OldLes]

It is thirty odd years since I took up TV repair, when I generally educated myself by reading Television magazine. I had "played around" with stuff for years (first Xtal set built in 1954), so it was not too difficult at that time. Twenty years ago, again with the help of Television, I (sort of) mastered CD repair. Then circumstances had me working with computers (hardware, NOT software) and the electronic repair side was left behind. Seven years since retirement, I have played about with the odd LCD set, but I don't have any real ideas about servicing them the way I did with TV and CD. I get the impression manufacturers either replace the lot, or sometimes a complete panel. I would much prefer to get back to component level, but I obviously need to re-educate myself. Where do I start? No TV mag today, so how do I learn this confusing technology? Advice please, OldLes.

[Ohm Supplies]

Oldles.

Have you tried reading service manuals? Start with an older model, always best as it will explain the basics much better, then work your way through them. I'd also recommend  getting a working set & figuring out what each bit does & why.

You know what goes faulty, how to measure & what each fault would show itself symptom wise. It's also a good idea when you get a faulty set trying.to diagnose the fault before posting for.help. I can certainly help you if you're serious about this.

Regards
Andy

[OldLes]

Hi Andy, thanks for reply. I guess if I search around here there will be manuals I can look at. Can you suggest an "older model with better explanation of basics" which I can download?
What are Philips manuals like, as I have a Philips Model 32 PF 3320 / 10 which I can play with. It has a smashed screen, but I think I may be able to find my way through the tuning menu by looking at the instruction book, and get it tuned in. If I get just enough picture to be convinced, and sound, I can then get some ideas from a working chassis. I also have a 26" JVC with scrap screen, but enough viewable to make sense from, but I hope to find a new screen for that so I have a digital set in the bedroom to keep SWMBO occupied whilst I am down here reading LCD manuals.
My first serious task, when I get a better idea of modern sets, is the TCM which I listed in the manuals forum.
Jordan has sent some manuals for that, but not all are suitable. Of course, they may be sufficient once I know where to start!
OldLes.

[Ohm Supplies]

Oldles.

You don't need to see whats on the screen, you need it working so you can read voltages.

What are they in stand by, what goes to the t-conn, the inverter, can you disconnect something & the set stay on?

We used to.produce a small monthly magazine for a short time, we stopped as no one read it. I'll send you.some pdfs when I find them, it will help.

Regards
Andy

[eklunge]

Dear Ohm,

Would you please also send the 'monthly magazine' to me. Thanks a lot

my e-mail : eklunge@yahoo.com.cn

[fix2003]

small monthly magazine pdfs
i would like to read them 2 are they uploadable here
cheers

[Keith]

Hi

there are several training manuals in the downloads section, I know 'coz I put them there! Unfortunately manufacturers service and training information isn't what it used to be, I don't think they expect equipment to be repaired out of warranty.

I will see if I have any other training stuff about.

Keith

[Davy]

Apart from LCD TV Courses which is as rare as rocking horse manure, there is only one way to learn... "get cracking" with 'hands on experience', that's how you learned the old method. These modern sets need a total different approach in servicing.

The main criteria I'd say is the power supply and inverter board, if it's a fault on the main board, then I'd reckon everyone would be scratching their heads for a while at least..... what is there to change, have you the tools should we have a chip down, will it be worth it? As someone on here said getting to know what voltages to expect from a psu is a good start which these must be 'hash free'.

The trouble with TV engineering and such like in this day and age is because these things are a 'throw away', many a folk won't even bother to have these repaired, there's the quote and the bill, I've had TV sets given to me as scraps when all they wanted was a psu re-cap.

I too started with crystal sets... those were the days!

[OldLes]

Keith, where exactly is the "downloads section", I can't see it. It is usually very obvious to others when I seem to be blind to the obvious. (It took me a while to realise that many "non-existent" circuits referred to in messages only appeared when I was logged in!) Can you point me to some of the training manuals you have downloaded?
Davy,yes, I know I need to just get "stuck in", but I have so many demands on my time that if I spend an hour today, it may be another week before I look again, so I almost need to repeat all the same steps.
For another couple of months I have the advantage of analogue signals as well as digital, but that changes soon. I am pretty well equipped with test gear, such as DVM, Avo, sig gennies (probably redundant), analogue storage and traditional scopes (mains and mains / battery) and other stuff.
Where I need to freshen up the grey cells is with a dead set, working out why? It seems that "Stop" signals appear from everywhere, and I need to get to the logic of where they all are, and which to look at first.
The main advantage I have is that the only pressures to complete come from me. Since I retired, I made the decision that I don't work for anybody for money. Myself, or good friends for free. I hope to present my son with a couple of LCD sets, but only if there is no significant monetary outlay. OldLes.

[Keith]

Hi Old Les,

If you look at the top of this page you will see 'downloads' just click that.

Modern electronic equipment is usually processor controlled, making fault finding very difficult! Protection circuits don't just monitor voltage and current. If the processor doesn't get the correct communication from all circuits it will shut down, which is why corrupt eeprom data causes lots of problems.
With LCD TVs it usually possible to force a power supply on so you can check for correct voltages and clean supplies. And you can usually force an inverter on too. Unless anyone knows of some tricks the only way to check a main board or Tcon is by substitution.
I don't do many TVs now as the customer usually says 'If it's gonna cost more than 20 quid we'll buy a new one'

This is a Sony training manual.
http://www.tv.quuq.org/index.php?ind=downloads&op=entry_view&iden=1391


Good luck

Keith

[Ohm Supplies]

Keith,

Although it can be difficult to measure, when we repair or replace them we measure the voltage in, on & if we can our of the t-conn. The voltage would normally drop or be missing.

Old les, I'll send the mag. to you shortly or in the morning as I forgot completely today.
Regards
Andy

[Keith]

Hi OldLes

I have emailed you some stuff as it's too big for this site.
Is your email address correct? It has bounced back undeliverable


Hi Andy,

I never seem to get faults with just a dc voltage missing! So it turns into a bit of a guessing game, but usually doesn't go any further as my customers very very rarely will accept used PCB's being fitted. If I can't repair to component level the job doesn't get done! I think people have been brain washed into thinking it's a throw away society. I have a Samsung 40 inch LED back lit set on the bench, under 2 years old, customer is reluctant to spend £50 to get it fixed!

At least we have a few days of Summer!

Keith

[OldLes]

Keith, I just checked the email shown in my profile, and it IS correct. Don't know why it should bounce, unless it was problems with Manx Telecom. I was told they did have some problems yesterday, but I was not aware myself. You don't show yours, or I would reply off list.
Thanks to you and everybody else, I am now getting the extra stuff the grey cells need to advance with LCDs.
Old Les.

[Keith]

Hi Les

tried several times but can't email you!

Go to this link            http://www.4shared.com/office/H1TM9hRO/LCD_Repair.html

then click the blue download box

You will need to sign up but it's OK you won't get loads of junk mail!

Keith

[OldLes]

Keith, many thanks, I have it now. I think the problem was its size. If I recall, 2MB was maximum email size a few years ago for Manx Telecom accounts, but it could be maybe 5MB today. At 19MB, this is surely too big.
Between 1980 and 1990, I had a Grundig spares account, so I got all their training manuals if requested (which they were), but they were mostly in English by their service department's translator, a chap named Caldecourt if memory serves correctly. Of course, I believe that company disappeared, and it is currently just a "name" for somebody else. (I may be wrong).
Even though the manuals were in English, there was still plenty of German to be found, so I picked up many technical terms and meanings which will stand me in good stead now, I hope. I always have my English - German dictionary.
Thanks again, Les.