37LH5000 Switches itself off

[Johnboy78]

Re: 37LH5000 Switches itself off

Could it be bad caps on the inverter board, although they do look ok

[tom66]

Re: 37LH5000 Switches itself off

Those can be tested if the BRI signal is found to be solid. If the BRI is varying there is no point in testing them because they would not be causing the fault. One test at a time, eliminate one component after another.

[Johnboy78]

Re: 37LH5000 Switches itself off

ok well ill report back when ive got myself a multimeter, thanks for your help so far!

[Johnboy78]

Re: 37LH5000 Switches itself off

Ok tom, update:

At standby i get 0.06
Then switch on values from bright to off is:

3.24 then
1.71 then
a range from 0.70 - 1.00

It goes through each stage quite quick so this is the rough values i get. Are these in normal limits? whats next to try?

[tom66]

Re: 37LH5000 Switches itself off

It should stay at one value, something on the main board is bad.

[Johnboy78]

Re: 37LH5000 Switches itself off

that plug goes to the main board though dosent it, would the fault be coming from the power supply to the main board or coming from it? if that makes sense lol

[Johnboy78]

Re: 37LH5000 Switches itself off

That was the brightness pin that i tested so in theory it would drop in voltage as it gets dimmer i would have thought?

[tom66]

Re: 37LH5000 Switches itself off

The signal is from the main board to the inverter or power supply, a lower voltage indicates the backlight is requested to be dimmer. (0V=10% bright (min), 3V=100% bright)

[Johnboy78]

Re: 37LH5000 Switches itself off

ok so whats next to test? and why would it be requested to be dimmer?

[tom66]

Re: 37LH5000 Switches itself off

I am thinking the software on the main board is bad, perhaps try applying a firmware update.

[Johnboy78]

Re: 37LH5000 Switches itself off

how would i go about doing that? it has usb i believe.

[tom66]

Re: 37LH5000 Switches itself off

I don't know, but there should be instructions on the LG website.

[Johnboy78]

Re: 37LH5000 Switches itself off

Ok ive just tried that, put the update onto usb and put it in, but it doesnt give you enough time to do anything as it turns off after the 3 stages of dimness

[tom66]

Re: 37LH5000 Switches itself off

Can you see any image when the picture goes completely dim?

[Johnboy78]

Re: 37LH5000 Switches itself off

no because after the 3rd time it then powers off.

[tom66]

Re: 37LH5000 Switches itself off

Hmm. OK.
Try pressing MENU on the remote and MENU on the TV. Hold both for 10 seconds. What do you see? If it prompts for a password, enter "0000" or "1234".

[Johnboy78]

Re: 37LH5000 Switches itself off

ive just tried that, just get the menu boxes up...the tv prob stays on for 10 secs or so while it does the 3 stages then powers off so doesnt give time to do anything.

[tom66]

Re: 37LH5000 Switches itself off

All I can suggest is main board replacement then.
Looks like it's around £25~£30
http://www.ebay.co.uk/sch/i.html?_od...+main&_sacat=0

These may also be compatible
http://www.ebay.co.uk/sch/i.html?_fr...644502&_sop=15

[Johnboy78]

Re: 37LH5000 Switches itself off

Thanks Tom ill try that.

[Johnboy78]

Re: 37LH5000 Switches itself off

Well its not the main board, got a replacement today and its still doing it. Could it be a bad TCON board or the inverter?