Samsung LN-T3753H Nothing on the screen no sound

[ny_jets_head]

When I got this unit it was dead, pulled the cover and found 4 bad caps.
Replaced the caps, now it sings the Samsung song when I turns it on,
It operates from the remote, I see the back light flash and then dim low.
I hooked it up to the HDMI to see if I had sound didn't .
I can't see anything on the screen.

I checked over the Power supply and all the voltages are there within range except the 13V.. I read 12.7.
There was a 1000 uf cap on that circuit which I changed still 12.7 V. I didnt chase down the regulator to see what it is supposed to output Its feed with 24V

Is this an issue or is 12.7 OK?

Any other suggestions.

Thanks

[tom66]

Re: Samsung LN-T3753H Nothing on the screen no sound

12.7V is OK for a 13V line, within tolerance.
Did you reset EEPROM after cap replacement?

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

I did not reset the eprom
Is there a "howto" for that?

[tibimakai]

Re: Samsung LN-T3753H Nothing on the screen no sound

If I remember correctly I had one of these and on mine it was a blown gamma chip on the T-con board which took out half the panel.
Try removing the panel ribbons to the T-con board one at a time.
You may have other issues, this is just what I have experienced.

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

If I remember correctly I had one of these and on mine it was a blown gamma chip on the T-con board which took out half the panel.
Try removing the panel ribbons to the T-con board one at a time.
You may have other issues, this is just what I have experienced.

Will do ... Thanks!

I tried

Samsung *****************************************-
Mute 182 power (tv is off)

But no change.

I connected my laptop to it an it was recognized correctly but again no output.

[ivoh]

Re: Samsung LN-T3753H Nothing on the screen no sound

check all smd fuses on tcon and mainboard? IMO the no sound suggests that the mainboard is acting funky, are you sure you got in to the right input, volume turned up, not muted?

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

Update: disconnecting one side of the ribbon going to the panel from the TCON Produced a brighter flash during power on with just parts of the panel bars. I tried both sides and got similar results.

Something must be causing the back light to shut down. It stays on briefly, just a flash and then goes off

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

check all smd fuses on tcon and mainboard? IMO the no sound suggests that the mainboard is acting funky, are you sure you got in to the right input, volume turned up, not muted?

Checked the fuses they are OK (Tcon and Mainboard , unsoldered the shielding to check what was under there as well.

Checked that I had the volume up, mute off and cycled through the inputs as best I could without the visual.

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

If someone knows has a service manual on this unit it would be appricated

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

If someone knows has a service manual on this unit it would be appricated

Please let me not close the door on suggestions..

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

Once it start up I receive 5v on the Bk light on pin should fire the inverter board and keep it on ? as when unplugged I get 0v and no flash of the back light.

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

Yup I'm an Idiot.. I guess being tired after work doesn't help..

New Info:
Its a back light issue Confirmed that the main board works I have picture and sound!

What I have:
BL/ on is 5v Which is good
VDIM is @ 3.5V
No back light , same as before just flashes when its powered on.
Checked the the fuses

Looking for advise on a starting point.

[tom66]

Re: Samsung LN-T3753H Nothing on the screen no sound

Sometimes there is a little fuse on these, can't see it from your photos but make sure you check it. Often marked "75", "10", "15", or "20", black body.

Since it is a Darfon inverter check transformer secondaries too.

[budm]

Re: Samsung LN-T3753H Nothing on the screen no sound

The small black fuse looks something like this, see F5. It is used a lot in CMO Inverter board

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

Thanks guys
I'm pretty sure I check all of them.
They seem to be in sections, I think I found 3 of them.
I will double check

[budm]

Re: Samsung LN-T3753H Nothing on the screen no sound

Beside checking the inverter transformer resistance, the eight dual MOSFETs (4 small legs and big tab on top), and those 3 electrolytic caps ESR and capacitance should also be checked.

[bammbammfran]

Re: Samsung LN-T3753H Nothing on the screen no sound

Did you actually check to see what kind of voltage is getting to the inverter ?
Picture is way to fuzzy for me to tell you where to start

[ny_jets_head]

Re: Samsung LN-T3753H Nothing on the screen no sound

If you are referring to my posted pic ... Sorry my cell phone was what I had handy before I left the house this morning.

I also have 24V,

So if I 5V for Back light on /off , 3.5V on Dim from the PS to the inverter.
Anything voltage wise on the inverter I should look for?

I'm assuming if one of the xformers is bad I'm looking for a short or open.
The short should blow a fuse or it has a way of shutting down which is what it seems to be doing.

[budm]

Re: Samsung LN-T3753H Nothing on the screen no sound

Post the P/N as printed on the transformers so we can look for the pinout.

[bammbammfran]

Re: Samsung LN-T3753H Nothing on the screen no sound

If you are referring to my posted pic ... Sorry my cell phone was what I had handy before I left the house this morning.

I also have 24V,

So if I 5V for Back light on /off , 3.5V on Dim from the PS to the inverter.
Anything voltage wise on the inverter I should look for?

I'm assuming if one of the xformers is bad I'm looking for a short or open.
The short should blow a fuse or it has a way of shutting down which is what it seems to be doing.

ok
so voltages look good
bad transformer may not blow a fuse
They may show an open reading on the output side where the bulbs plug in

a shorted transistor might blow a fuse if it is really shorted

compare each transformer outputs to each other
and check each pin on the 8 transistors to each other. Large tab to small pins on one side then to small pins on the other side then small pins to small pins