LG flatron L1718S - shaky picture when not in native resolution

[selldoor]

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

Hey man.Nah, no update. Still waiting for the damn voltage regulator.

I bought some off that ebay site - I'll let you know when I get them then if you still need Ill post you a couple.

[bocca]

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

Was the problem present before the recaping too? I mean, backilight on, no picture

[selldoor]

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

bocca -

Any update with this?

I did a total re-cap of the PSU and logic board, but I'm still stuck witht he same symptom... backlights come on but no picture. Can't see the OSD either. It's not a white screen, just no picture.

Did you test your voltage regulators?

[bocca]

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

Hey man.

Nah, no update. Still waiting for the damn voltage regulator.

Did you try those 4 cables that go to the PSU? Are they OK, power coming thru clean? If the backlight is on, then logic board is letting the power through, but signal from the video card is not being trasmitted. Maybe the buig chip itself has gone bad?

[mockingbird]

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

bocca -

Any update with this?

I did a total re-cap of the PSU and logic board, but I'm still stuck witht he same symptom... backlights come on but no picture. Can't see the OSD either. It's not a white screen, just no picture.

[retiredcaps]

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

Looks like Kapton to me. Kitchen foil will also do the job, cover up everything you want intact.

Yes, Kapton tape. It is trademark of Dupont. You can find it widely available on ebay. I got 100ft of the widest tape I could find with the thought that I can always cut it into strips.

Aluminum foil works as well, but I don't know how to secure the foil down to the board and not have it blow away.

[tom66]

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

Very interesting! What kind of tape is that exactly? I thinh i've seen it couple of times in laptop mobos.

One question. Is desoldering wick of any use with SMD's?

Looks like Kapton to me. Kitchen foil will also do the job, cover up everything you want intact.

Desoldering wick is very useful for SMD work. I sometimes find it is easier to flood the pins of a SOT223 with solder so they are all bridged, then wick it all up so the three pins are loose, then I heat up the tab and try to lift it.

[bocca]

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

Very interesting! What kind of tape is that exactly? I thinh i've seen it couple of times in laptop mobos.

One question. Is desoldering wick of any use with SMD's?

[retiredcaps]

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

oIn the meantime i found one on the old motherboard but fried it while desoldering.

I remove those SOT packages like so

https://www.badcaps.net/forum/showpo...&postcount=139

[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

[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)

[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.

[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

[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

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

[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

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

[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

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

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?