32lm3400 dead no standby

[jonny78]

Re: 32lm3400 dead no standby

thanks budm! resistor is fine! what about the mosfet MDF10N65B ? i cant find this available in the uk is there an equivalent? ill give it a shot with a new mosfet then move on if it doesnt fix it!

[dick_barton]

Re: 32lm3400 dead no standby

See if you can find one of the equivalent from the list here

[groovejet]

Re: 32lm3400 dead no standby

i know this is a old thread but has exactly what im after, although this thread seemed to of ended quite abrubtly? i guess the guy found what he needed and buggered off? Always good to have good housekeeping...

[groovejet]

Re: 32lm3400 dead no standby

if i started my own thread ? How could i link this thread into mine? Without repeating it all?

[R_J]

Re: 32lm3400 dead no standby

if i started my own thread ? How could i link this thread into mine? Without repeating it all?

Then if everything is the same, and you have 0 volts across the main filter cap, You likely have an open fuse, open TH101 thermistor, or a broken trace between the line in and the bridge rectifier.

[groovejet]

Re: 32lm3400 dead no standby

ill look into it today but from what i remember, i have both 3.5vdc lines. Which go over to main board also.
The fuse is intact and i have 240vac in.
No standby light,
Ill have to check the rectifier.

[groovejet]

Re: 32lm3400 dead no standby

rectifier reads ok.there is a area ON BACK BOARD NEAR WHERE THE CONNECTOR plugs to take power to main board. There is a selection of surface mounts that look suspect. not burnt but just look dirty .ic202, r205, q201?not sure thats correct last number.
the ic and the q201 look identical and wouldnt of known they were differant unless board told me so.

[R_J]

Re: 32lm3400 dead no standby

If you have 3.5v standby, you need to check if you have the PWR-ON command from the main board. The PWR-ON pin should change when the power switch is pressed, if it does not I would suspect the main board has a problem.
The power supply can be tested seperately if required.

[groovejet]

Re: 32lm3400 dead no standby

ok thankyou RJ

[R_J]

Re: 32lm3400 dead no standby

If you want to check the power supply, disconnect the cable going to the main board, then find a resistor close to 1k and connect it between 3.5v standby and PWR-ON, this should turn on the +12 & +24v

[groovejet]

Re: 32lm3400 dead no standby

lovely, thats a great tip,ill do that later today

[groovejet]

Re: 32lm3400 dead no standby

going to have to look deeper into this, i havent got 3.5vdc anymore and i measured theb.rectifier and got 120v,110v and no dc volt readings. 120 and 110v are there about, they were few more volts to be exact

[Hartk311]

Re: 32lm3400 dead no standby

Thanks for the information on this issue, I believe it to be the same thing I am diagnosing now. I'm new to the site but will be using it as often as issues arise. I appreciate everyone's sharing of knowledge

[pierce012]

Re: 32lm3400 dead no standby

So I have this same problem on an LG 32LM3400. I have got all supplies coming out of the connector but have got no LED on. I noticed a strange constant noise on the PSU even when I unplugged the main board. Any help please?

[nomoresonys]

Re: 32lm3400 dead no standby

what kind of noise high pitch, low pitch, clicking, buzzing? a little test is put a small hose to your ear and listen to it to try to determine exactly where its coming from, careful not to touch any live sections with your hands, potentially DEADLY voltages on hot/primary side of board.

[nomoresonys]

Re: 32lm3400 dead no standby

could use a wooden dowel rod or stick also, maybe use a non conductive same piece of wood to gently tap or nudge the components to see if you can detect it, the component will probably change a slight bit in sound when you find it, also check over your solder joints closely, reflow any that look suspicious, careful not to bridge any joints, examples of bad joints there: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

[pierce012]

Re: 32lm3400 dead no standby

Seems like it’s coming from the 3.5v transformer. Eventually the TV started but I am very happy with that low pitch sound. But I will have to recheck tomorrow. Thanks for the time being. Goodnight ����

[nomoresonys]

Re: 32lm3400 dead no standby

ok, might just need to resolder the joints on that transformer.

[pierce012]

Re: 32lm3400 dead no standby

Refreshed the transformer soldering. Hissing/buzzing sound stopped, voltages all present but standby led still off. The TV does not respond to Tv instantly but eventually after 10 minutes it starts. What could it be?

[nomoresonys]

Re: 32lm3400 dead no standby

I might suspect one or both of those 2 electrolytic capacitors there by connector P201.