LG flatron L1718S - shaky picture when not in native resolution

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

I found them. There's two of 'em, both 22uf 25v. As far as I can see no ESR stated on them. Only other marking except temp rating (105) is 0627(M). Guess that's model.

@tom66:
Don't have the datasheet. Sore i found them in is small. They don't even have the website. I'll go there tomorrow to try to find the right ones. Sadly, any kind of online shopping is a thing of imagination here, so there's 4-5 stores to buy from and that's it.

@retiredcaps:
Found the battery of one cell phone which give 4.12v constantly (good battery, smashed phone) so i tried with it but it's fat too complicated to connect to board. I'll think of some other way

[tom66]

Re: LG flatron L1718S - shaky picture when not in native resolution

You're lucky to even have electronic parts shops, in the UK the only one left is Maplin and they only seem to sell disco lights and car stereos!

If you record the series on the capacitor (something like two to three characters) then the ESR can be looked up.

[mockingbird]

Re: LG flatron L1718S - shaky picture when not in native resolution

@mockingbird:
That would be great, mate! I appriciate it

Hello to you in Serbia. Long live Serbia!

I just want to say that whoever designed this one was a masochist. I've taken apart LG screens before, with this one, I couldn't figure it out until finally I found the service manual and this important picture:



Ok firstly, the PSU:



Circled are the two groups of pi filters. We can do a little better spec-wise and matching the ESR:
1) 25V 1000uF 13x21mm - Replacement
2) 25V 470uF 10x16mm - Replacement
3) 35V 150uF 8x12mm - Replacement

1) 10V 1000uF 10x16mm - Replacement
2) 10V 1000uF 10x16mm - Replacement
3) 35V 150uF 8x12mm - Replacement

For the 25V 47uF caps, you can use anything, but it's best to use a
high quality cap (Don't forget to get 4 of these).

For the logic board, here are the caps:
1 x 16V 220uF 6.3x11mm
2 x 25V 10uF 5x11mm
2 x 16V 100uF 5x11mm
5 x 16V 22uF 5x11mm

Good luck.

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

hahaha, you seem to love Serbia more than I do

Errr, yeah, about that stand. I never found that service manual, but did exactly the same thing as illustrated. My motive was "I'm either gonna take off this damn stand, or I'm gonna break the mother***ker, it's all the same at this point", having tried for about 2 hours

Thank you very much for the schematic. Tomorrow I'm getting two of the 22uf, 16v and I'll see if that fixes the problem

[Scenic]

Re: LG flatron L1718S - shaky picture when not in native resolution

In this application, Yageo may be okay. They are formerly Philips/Vishay caps so better than no-name junk.

Yageo = Teapo
The only thing that's different is the name. Even the series are identical.

For example:
Yageo SC PDF -> link
Teapo SC PDF -> link1 link2 (2 somewhat different versions of the same datasheet)

[retiredcaps]

Re: LG flatron L1718S - shaky picture when not in native resolution

The datasheet doesn't mention a maximum input - I know some regulators are limited to just 6V in! - so try and stay within this limit.

Yes, I caught my own error after posting in post #15

Most of the time, I use *weak* 9V batteries. The one in the picture is 7.3V with no load. I find it easier to clip on leads versus doing multiple AA cells in series.

The voltage regualtor in the picture, obviously, is a fixed 3.3V. I do have a 1.8V, but the 3.3V is the one I had handy. Cloudy day so I had to use indoor flash so not my best work.

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

OK, i think i measured 102. It peaks to 1.60v for a brief moment and then drops to 0. Battery is stable 4v

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

I changed two caps we were talking about and no change noted... Sadly I can;t seem to find this particular IC, that has output voltage of 1.8v. Closest is 3.3v.

Aly alternatives?

[tom66]

Re: LG flatron L1718S - shaky picture when not in native resolution

I changed two caps we were talking about and no change noted... Sadly I can;t seem to find this particular IC, that has output voltage of 1.8v. Closest is 3.3v.

Aly alternatives?

Look for AS1117, or LM1117, or LD1117, or AM1117. -18 is the output. Can eBay sellers ship to you? If so, http://www.ebay.co.uk/itm/2-x-SMD-SM...item3f06fd6467 or http://www.ebay.co.uk/itm/20x-AMS111...d#ht_779wt_956 (pack of 20, you'll be able to fix 19 more monitors. )

If not, you could do what I did to fix this 32" TV; I built a little regulator board (with an LM317T, cheap and plentiful device) and fitted it in the chassis. However, that TV had a lot of spare space inside; I'm not sure a 17" LCD would have enough space.

[selldoor]

Re: LG flatron L1718S - shaky picture when not in native resolution

Or if you just want ten and are lucky with bid and can wait for it
http://www.ebay.co.uk/itm/10pcs-AMS1...a7553eb8f#shId

Although he is new so low feedback - might even bid myself for 99cents?

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

They probably can ship but i have no ways of paying for it as serbia is not in Paypal, sadly.

Tell me, would the variable voltage ones do?? I can find some that have var output from 1.5v up until 30 or something

[selldoor]

Re: LG flatron L1718S - shaky picture when not in native resolution

Do you have one where you can read the part number - we can then get a data sheet and see if/how.

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

Here's the store page. you'll find pdf link

http://www.mikroprinc.com/proizvodi/...217t/index.php

here's the direct link for the dfatasheet, i hope it works. if not you can download it from the webpage above

http://www.mikroprinc.com/index.php?...emart&Itemid=8

[tom66]

Re: LG flatron L1718S - shaky picture when not in native resolution

You can build a little circuit on a bit of prototyping board or stripboard to do it with the LM317T.

Use input capacitor 100uF or above (any cap with good voltage rating is okay here.)

Use output capacitor 100uF or above (again any cap is fine, as long as voltage is okay.)

From the output pin tie a 220 ohm resistor to the adjust pin.

Then the adjust pin gets a resistor of value 470 ohms, this will give 1.836V, with a 5% tolerance, which is fine.

Optionally add a red LED on the output, with a 10 ohm resistor, to indicate output is active. (Most red LED will be fine with 1.8V.)

Tie the input to a 5V source.

I would recommend adding a heatsink to the LM317T too, and applying epoxy or hot glue to hold big components down. Insulate the bottom of the board with electrical tape and find a good place to put it inside the monitor.

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

thanks tom. I'll get to it right now!

[retiredcaps]

Re: LG flatron L1718S - shaky picture when not in native resolution

Sadly I can;t seem to find this particular IC, that has output voltage of 1.8v. Closest is 3.3v.

Aly alternatives?

Check your junk or dead boards. The 1.8V regulator is a fairly common part. For example, I found one on my old sound card.

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

I may be having some combination to get it but i'll surely check old components. There's lots in my office!

Thanks

[tom66]

Re: LG flatron L1718S - shaky picture when not in native resolution

thanks tom. I'll get to it right now!

Remember to check your board before you wire it in with a voltmeter. Echoing Retiredcaps though, I have found old laptop and computer motherboards to be a goldmine for replacement regulators.

[tom66]

Re: LG flatron L1718S - shaky picture when not in native resolution

Just a correction to my previous post - realised I was being an idiot - use a 330 ohm resistor instead of 470 ohm in the lower resistor. This will give 1.87V. Even better use a little potentiometer of 500 ohms in place of the 330 ohm resistor so you can adjust the output.

My previous suggestion would have given 2.65V!! I was using the wrong formula. The correct formula is 1.25 * (1 + Rlower/Rupper)

[bocca]

Re: LG flatron L1718S - shaky picture when not in native resolution

oh, OK. Thanks. I bought everything for the circuit but still waiting on one store to send me response about the IC. In the meantime i found one on the old motherboard but fried it while desoldering. At least I learnt from the mistake so I'm looking for another one. Most are 3.3v