LG 34UC87M-BD.AUSLay Monitor

[SolomonMan]

All,
Got this the other day from work. Tossed to the recycler and I grabbed it before it left the building.

Anyways the screen is black...no life I can see at all from the unit.

Tried to do a Dark Room and my phone light to see if I see anything and I did not even when pressing the bottom Joystick button.

I am going to try and hook a HDMI cable to it and try things again but the unit was found dead according to my colleague hooked to a working PC. Swapped the Monitor out and the user continued with their original PC.

I tested the power supply 19 volts...It was originally thought to be a bad power connector on Monitor but my testing I have done shows the Main board is powered past the connector and thru the back monitor switch and to multiple locations all over the board.

Seems like the backlight connectors (there are 2 - one for each side of this 34 inch curved panel) pins 3 and 4 on both connectors have 19 volts but no backlights are lit. Seems constant...Tried it a time or two.

I pulled the main board out of the monitor and did a once over under light and magnification and nothing looks burnt/unusual. Included are scans of the board.

Did the ground and both side of each capacitor with tone test and did not find anything with tone on both sides of any single capacitor. I did find some though without tone on either side....Not sure if this is ok or not...?

I have not done diode tests but am wondering why no backlights?

I believe there is a TCON board in this monitor but I believe its under the lower plastic Bezel/Cover. I am assuming that the 4 cables one must have power in it and go to the TCON board.

Is there a repair manual for this Monitor? If anyone has one I would greatly appreciate it.

I am guessing I probably should dig deeper into the monitor but was also wondering is there a "Order of Operations" in LED monitors and no Back Lights is a clue to investigate before going further into things (TCON).

Thanks for all the help,
Chris

[Michael Long]

Re: LG 34UC87M-BD.AUSLay Monitor

Have you had any luck with your repair? I've come into possession of the identical monitor with your exact issue.

[Michael Long]

Re: LG 34UC87M-BD.AUSLay Monitor

The Issue is a Stuck EEPROM from a power outage that left the IC205 in the Incorrect
state rendering the monitor dead.

I used a Fluke Multimeter that was set to Volts DC. Held the POSITIVE probe to the board on 19V+ power jack location , and the NEGATIVE to the SCLK* leg. *Held the probes for some time, then an Audible Tone is heard as your monitor turns on again. I had this work the first time but then removed power and EEPROM was stuck again. So I removed power from the Monitor for a few minutes and repeated the procedure until the Monitor was stable. Don't give up try again until Monitor can be powered down and restarts repeatedly.

[Michael Long]

Re: LG 34UC87M-BD.AUSLay Monitor

New Notes:
Related Info on badcaps.net forum site: Search LG 31MU97 no power...

and URL with this discussion: https://integer13.wordpress.com/2018...-piece-of-sht/

[SolomonMan]

Re: LG 34UC87M-BD.AUSLay Monitor

Michael,
Thanks for the info....I had it on my back bench for a while... I will give it a try later this week....

Currently have a Samsung 58 inch plasma and my Variable PSU as my main focuses.

Thanks again,
Chris

[SolomonMan]

Re: LG 34UC87M-BD.AUSLay Monitor

Michael,
Thanks for the info....I had it on my back bench for a while... I will give it a try later this week....

Currently have a Samsung 58 inch plasma and my Variable PSU as my main focuses.

Thanks again,
Chris

Michael/All,
Yes this seems to get the Monitor back on again...picture looks very good.

I unplugged and ran into the problem almost immediately again.

I did a series of two things;

1) In Ohm Mode (20K) (Cheap Digital Multimeter (Harbor Freight free one - quickest-top of the toolbox)

2) I Switched back and forth (Positive Lead on the 19+ solder connection on the 19V plug connector on Main Board...Then on the negative/ground solder connection of the 19V plug.

3) Placed the black (negative) lead on the SCLK and then on the #CS pin.

First time I heard some weird speaker noise like space invaders. Then tried it again (it actually startled me) this time heard a clear ding noise from speakers. Took about 20 seconds at each the for attempts (points) before ding is heard.

This worked until the unit powered down into power saving mode. I turned it on and off a few times with no problem from the power switch. (Please keep in mind previous to this power on I had no idea if this thing was a brick/junk or how to turn it on.)

When I went to unplug the power supply to reassemble the board back into the monitor...I thought to myself I bet if I reassemble it will not work again...sure enough it did not work again. (glad I did not reassemble...lol)...As I disassembled it over two months ago I had some time to think about it as I honestly did not remember how to reassemble.

So I plugged it back in and did the process outlined above (quicker this time)...I hooked a HDMI DVD player to it just now and currently watching a video...thinking maybe use will kick it out of its "groove" its in.

So my question is what am I actually doing to this IC to make this thing work?

Someone mentioned the Processor on the board is stuck in a loop and this is getting it out?

Someone on the link above also mentioned updating the Bios and another said resetting the power saving mode helps...Anyone have any opinions on either approach and if the bios update helped...How to update the Bios?

https://integer13.wordpress.com/2018...-piece-of-sht/

Thanks all (Michael) for the help!
Chris








So now I am trying to

[SolomonMan]

Re: LG 34UC87M-BD.AUSLay Monitor

All,
No Luck on getting it out of its "Groove".....but the movie played all night last night (8+ hours) and as of this morning it was still a good looking monitor etc.

So I am thinking of either sending the board possibly out for service or replacing the main board entirely.

The Main reason is I cannot get the thing to continue to be functional after assembly or partial assembly attempts...Any Ideas?

Thanks again for all the help,
Chris

[SolomonMan]

Re: LG 34UC87M-BD.AUSLay Monitor

Guys,
I went the route of a replacement (fixed/refurbished) board on Ebay...cost $95...For the monitors worth it was worth the investment not to mention the boards used go for twice that amount almost.

The board arrived at the destination and the new board went out the same day...My guess looking over the board it was a swap out.

Installed the board and have done many on and off tests. I turned off the power saving mode.. The power saving mode on this monitor drives me crazy not to mention from reading its one the problematic issues with this monitor.

Below is an example of the Monitor running.

Thanks everyone for the help!
Chris

[Michael Long]

Re: LG 34UC87M-BD.AUSLay Monitor

What did you do with old Mainboard any chance it is available... can't hurt to ask

I acquired an identical Monitor but this one has a Burnt Chip and I need a parts board.