LG 42LD560 No go

**aarty** · 15-08-14, 05:10 PM

Hi there Guys,

I have a 42LD560 with a power on problem. The set doesn't come on at all. The red standby light in the middle flashes on and off very slowly. I have checked the power supply and from the board markings the voltages are there. The only one that I am unsure of is the "power on" one. When I switch it on, for a split second it goes 5v down to 3.2v and stays at that.

The caps look ok, I will replace them just in case, but do you think this suffers the same as the Samsung eeprom?

Any help would be great if possible.

Thanks in advance.

Arty

**CHRISS** · 15-08-14, 09:57 PM

Hi Arty
will look up on Monday for you i think it may have the power supply with the faulty cap about .39yf at top of power pcb ,think its a big black cap next to heatsink in middle at top of power pcb
i have not had eprom problem like the samsung with lg apart from upgrades on old models

Chriss

**CHRISS** · 18-08-14, 04:12 PM

If it has the EAY62609701 power supply in your set it will be C802 .22 mf cap
i look up model and did not find any upgrades for this model may have a main pcb problem

**aarty** · 18-08-14, 11:44 PM

Hi Chriss,

Thanks for getting back to me.

The board I have is different.... It is a EAX61124201/15...

Well do some checks and go from there...

Thanks for your help.

**aarty** · 28-08-14, 11:30 PM

An update peoples.

After replacing the caps there is still no go. I have checked voltages and there correct except the inv on/off one. I get nothing there. Should there be a voltage there or is it a command to turn the inverters on?
On the main board there is a little tact switch (sw8100) which when I press it for a split second the back lights do come on then unit goes back to solid standby (no led red light blinking).

Does anyone know what that switch is for? to test the back lights or something else?

Thanks peoples.

**tristen** · 29-08-14, 12:08 PM

Aarty, you will find the service manual for this model at .

I hope that it helps you.

**aarty** · 29-08-14, 12:47 PM

thanks for the manual tristen....

now I know the switch is to reset the micro on the main board which the inv ctl. rl on are also on that chip.....

back to checking again.

**TVguy** · 30-08-14, 01:36 AM

Originally Posted by aarty

back to checking again.

To check the inverter and backlights: remove the plug from the PSU to the Main PCB, then use the method below to force the PSU and inverter ON. This will confirm whether the PSU/Inverter or CCFL tubes are functional.
This is a general diagram and the plug reference is different to the LD560 as is some pin labeling . Try to avoid blanket changing of electolytic capacitors; use an ESR meter to check for faulty caps.

The sub-microcontroller IC8101 Renesas type UPD78F0513AGA-GAM-AX is responsible for basic housekeeping: Power Control, IR, Key, RS232, RTC, Preference Settings, etc. If the main PCB is defective you will need to probe crystals and low voltage buck regulators for signs of activity. Most likely the Broadcom SOC has expired; these BGA devices run hot and develop dry joints on the balls. Good luck and always use an isolation transformer at all times when working live.

**aarty** · 02-09-14, 12:20 AM

HI there TV Guy,

Thanks for your advice. I did the connector test on the p/s. The back lights came on for 5 secs then switched off. Is this the norm for testing? If it is I guess it means the main board has the issue.

Thanks in advance.

**TVguy** · 02-09-14, 08:40 AM

G'day aarty,

The backlights should stay on as long as the test links are in place. If all the PSU rails remain stable (correct voltage) the inverter should keep the backlights on. This model uses EEFL tubes which are very reliable but can suffer from poor connection at the end cap/socket interface. Before pulling the panel assembly apart, check all components in the inverter voltage generation circuit. An image of the PSU/Inverter PCB would be of assistance (both component and trace sides).

Cheers

Sent from my iPad using Tapatalk

**aarty** · 02-09-14, 11:09 PM

hi TVguy,

Thanks for helping me out.

I have the pics for it. Checking last time the little transformers on the inverter side of the p/s had no voltages feeding to the fets for the inverter transformers. I noticed the solder side of the board it had an IC BD9270F which is some sort of an inverter chip. I am only guessing that is the fault. I do have 12v VCC going to it. But from there it goes to the smaller transformers which have no voltage at all. I just don't know if it is shutting down due to a protection. Have you had this fault also?

**tristen** · 03-09-14, 11:29 AM

Originally Posted by aarty

...I have the pics for it. Checking last time the little transformers on the inverter side of the p/s had no voltages feeding to the fets for the inverter transformers.

Invalid Attachment specified. If you followed a valid link, please notify the administrator

**aarty** · 04-09-14, 11:20 PM

Sorry... didn't check it....

I'll try again

don't bother.... didn't work again

**aarty** · 04-09-14, 11:28 PM

Hi guys,

I got this pic from the net.

Also underside looks like this

I hope this works now.

**tristen** · 05-09-14, 11:34 AM

Originally Posted by aarty

Hi guys,

I got this pic from the net.

Also underside looks like this

I hope this works now.

Yes, that's good now.

Uploading your original images to one of the file storage sites such as depositfiles, mediafire etc. or the image hosting site, postimage.org, and posting the links would also be O.K. It's only forum attachments that are currently a problem.

**TVguy** · 06-09-14, 11:16 AM

Hi aarty,

The fact that the lamps are striking indicates the inverter circuit is mostly working. The backlight lamps are driven by a full bridge circuit feed from the full PFC voltage rail of ~400 volts DC. The BD9270F inverter controller IC has feedback to sense current flow in the lamps and will shut down if an error is detected. The basic circuit topology is shown below (note that circuit references may not match your hardware):

The EEFL tubes (External Electrode Fluorescent Lamp) are a weak link as previously mentioned. They are mounted in sockets which can develop high resistance connections and the tube end caps can fatigue. For some light reading, check out the wonderful world of . Certain SONY panels suffered from problems with these connections and if you are inclined to disassemble the panel, please do so in a dust free environment (a Class 10,000 Cleanroom is recommended). A typical lamp mounting structure is shown below:

Keep us posted on your progress.

**ant747** · 12-01-15, 10:07 PM

Hey guys,

Im having the same problem with my 42ld560, Ive tested all the psu, and the inverter and backlights, with the test links in they stayed on no trouble.
So im guessing the main board is done, any suggestions on where to source a new one or most likely point of failure? Ease of replacement?
Cheers
Antony

**aarty** · 20-01-15, 12:42 AM

Hi all,

Mine looks like led issue. From memory 2 tubes were ok but the rest down the middle are not lighting up. I strip it to bits then put it back together again.

If you are in Melbourne I will sell the whole tv with remote.

Regards,

aarty

**ant747** · 21-01-15, 08:24 AM

Hi aarty, sorry to hear you didn't have a win. I'm located over in Perth, I'd like to purchase the main pcb off you if your willing?

**slc** · 12-11-18, 04:59 PM

Originally Posted by TVguy

To check the inverter and backlights: remove the plug from the PSU to the Main PCB, then use the method below to force the PSU and inverter ON. This will confirm whether the PSU/Inverter or CCFL tubes are functional.
This is a general diagram and the plug reference is different to the LD560 as is some pin labeling . Try to avoid blanket changing of electolytic capacitors; use an ESR meter to check for faulty caps.

Hi TVguy, the link to the image is no longer working. Are you able to send through again please? I am troubleshooting an LG42LD560 with the same symptoms. The backlight flashes on when I press SW8100.

Thanks.