LG model RM-26LZ50 is slightly blurry

[soldercap]

Need help trouble shooting. I got this tv from a friend and the picture is distorted just a bit. For instance when showing numbers you can make them out but it is not aligned as they should be.
So far I have tried another cable outlet and also used a DVD player and got the same results. From what I have briefly read here, it might be the Tcon board, but any other insight would be appreciated

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

Can we see a picture of the distortion?

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Thanks for the quick reply. I will get it to you later.

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Here is a photo of what the picture looks like

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

We have seen this before. Often it is due to a failing voltage regulator on the main board, relatively easy to find and replace. Does this TV have any digital inputs e.g. HDMI/DVI. If so is it different on these compared to analog sources?

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

yes it has a DVI

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

So, on DVI, does it look the same, with that noisy/unstable look to it?

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

I will check. Right now, I do not have a DVI cable to hook up
Thanks

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

I am going to bed now, but if you post some pictures of the main board after doing the test I describe, I will help with further diagnosis. The main board is the board you are connecting the video inputs into and will be visible upon removing the case. Clear detailed photos are preferred as we don't have the boards in front of us and they are our eyes.

[jbfr_54]

Re: LG model RM-26LZ50 is slightly blurry

I had two of these sets doing the same thing a few months ago. All voltages were good but on the main board (SSB), the power lines around the video circuit were very noisy (above 100millivolts). This was due to bad electrolityc caps (aluminium surface mounted) that I had to replace by new ones. As I did not have the SMD types, I replaced by conventional ones, there is enough room to put them.
I cannot remember which ones I had to substitute but if you have an oscilloscope, check the positive pole of the electrolytic caps that have there negative wire connected to ground (unless they are not filtering caps). The noise over the positive wire should be less than 100mV. If not try to place a capacitor of same value in parallel and watch your image. Warning, do not parallel the cap when the set is powered as you could damage the regulators due to the surge an uncharged cap would produce on the regulator or switching transistor on the line under consideration.
I will try to give you a picture of the fixed board and the ID's of the capacitors on the board as I still have one of these sets.
Good luck.
Jean

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Thanks for the help, but I do not have the cable to hook up to the dvi, and today it is a holiday so will get it tomorrow

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

I was able to get a dvd player with a HDMI output and used the hdmi to dvi cable to connect to the TV. Picture is perfect!!
Do you want the pictures of the main board?

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

Yes, please. This confirms the issue is in the analog processing side and narrows down the fault.

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Is this picture good enough

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

That's more than good enough. Thanks for supplying a good picture.

Read retiredcap's guide on diagnosing faulty regulators:
https://www.badcaps.net/forum/showthread.php?t=22231

and supply the list in the format suggested.

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Thanks. It's hard to see the part numbers on the regulators. So I was looking for a parts list fro the board but no luck.
What did you mean supply the list in the suggested format?
Pin 1
Pin 2
Pin 3 ?

[tom66]

Re: LG model RM-26LZ50 is slightly blurry

Suggested format is:-

AS1117-33 -> line 1 of the IC
0506 -> line 2 of the IC
pin 1 = 0.000
pin 2 = 3.301
pin 3 = 5.001

As an example. The readings are taken in volts DC, 20V scale (if not autoranging), with black probe on chassis of TV, red probe on each pin. The larger "tab" pin is physically connected to pin 2; this may be easier to probe than pin 2.

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Good that's is what I thought. Will attempt this in the next hour or so

[soldercap]

Re: LG model RM-26LZ50 is slightly blurry

Sorry for the delay but unfortunately not all the chips are marked the way you described.
I was able to get hold of a service manual and part list for that circuit board.
It was from LG with the same chasis...ML-041A
I will use the circuit board number and give you the chip number. here is an example
IC2, IC4, IC601 all used 1117A-33CYTR, but on the chip was B533399GC
Pin 1=5v
pin2= 3.2v
pin3= 0v
Will this be ok
After collecting all the data something did jump out at me it was
IC3...very small and numbers on the chip are not readable according to the parts list it is
KIA7027AF3
pin1 = 3.2
pin2 = 0
pin3 = 3.2
but I am not sure what the readings should be
I can give you the rest of the readings if the format is ok with you

[retiredcaps]

Re: LG model RM-26LZ50 is slightly blurry

IC2, IC4, IC601 all used 1117A-33CYTR, but on the chip was B533399GC
Pin 1=5v
pin2= 3.2v
pin3= 0v
Will this be ok

Unless you have an analog multimeter, report all the digits that the multimeter shows.