Samsung UN55B7000WF - backlight present but no image

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

have to head out so unable to do full check.

voltage readings with TV on are 131.5 one way and 11.93 the other way. Does that sound better?

Also...when checking the ohms. Putting the probes on either side of fuse got a reading of 000.0 one way, and then simply "Open" on the screen when I reversed them. No beep either way.

I will need to check the other stuff when I get back home tonight.

[martino]

Re: Samsung UN55B7000WF - backlight present but no image

Just for clarity,I numbered the fuse sides......(see pic)

With TV UNPLUGGED: meter on ohm(beep mode),red probe on 1,black on 2,what is the ohm reading? And maybe reverse red and black also,read again...

With TV plugged in and ON: meter on 20volt DC,black probe on chassis or a screw on the tv,red probe on 1=.... volts? Then with red probe on 2=....volts?

**little confused here:
I Assume you mean 13.15volts and not 131.5?
Also,13.1`5 the one way,11.93 the other way? As in one side of fuse and then OTHER side of fuse or same spot but probes of meter reversed?
000.0 one way,open with probes reversed,that almost sounds as if your measuring a diode(unless a diode is parallel to the fuse,seems unlikely)
I hope you don't measure OHMS while tv is ON,cause you can't do that...**

[martino]

Re: Samsung UN55B7000WF - backlight present but no image

have to head out so unable to do full check.

Hurry back,we're not done electrocuting you...

[selldoor]

Re: Samsung UN55B7000WF - backlight present but no image

Hurry back,we're not done electrocuting you...

131 volts on a tcon - yes?



No !!

[budm]

Re: Samsung UN55B7000WF - backlight present but no image

May be 131.5mV? Need to see the meter, I can also tell that the meter was not set to 20V scale otherwise it would have shown OL, it is more likely to be in the auto-range mode. Invalid reading or not proper reporting what it is showing on the scale (I.E. mV, V, etc.) is always hard for us to help troubleshooting the problems.

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

Just for clarity,I numbered the fuse sides......(see pic)

With TV UNPLUGGED: meter on ohm(beep mode),red probe on 1,black on 2,what is the ohm reading? And maybe reverse red and black also,read again...

With TV plugged in and ON: meter on 20volt DC,black probe on chassis or a screw on the tv,red probe on 1=.... volts? Then with red probe on 2=....volts?

**little confused here:
I Assume you mean 13.15volts and not 131.5?
Also,13.1`5 the one way,11.93 the other way? As in one side of fuse and then OTHER side of fuse or same spot but probes of meter reversed?
000.0 one way,open with probes reversed,that almost sounds as if your measuring a diode(unless a diode is parallel to the fuse,seems unlikely)
I hope you don't measure OHMS while tv is ON,cause you can't do that...**

TV unplugged measuring ohms as described above: 12.8 first way, 0.F apears the 2nd way (over range I assume)

TV plugged in and powered on and measuring volts: 11.93 one way and 131.2 mV the other way. My meter is on AUTO

[budm]

Re: Samsung UN55B7000WF - backlight present but no image

"TV plugged in and powered on and measuring volts: 11.93 one way and 131.2 mV the other way. My meter is on AUTO" Do you mean one end of the fuse show 11.93VDC, and the other end of the fuse shows 131.2mV? Sounds like blown fuse.

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

"TV plugged in and powered on and measuring volts: 11.93 one way and 131.2 mV the other way. My meter is on AUTO" Do you mean one end of the fuse show 11.93VDC, and the other end of the fuse shows 131.2mV? Sounds like blown fuse.

Yes budm. That is correct. 11.93 V one way and 131.2mV with the probes reversed.

[selldoor]

Re: Samsung UN55B7000WF - backlight present but no image

I would say the fuse is open ( bring back the $5 meter )

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

I would say the fuse is open ( bring back the $5 meter )

Does this confirm the issue is with the tcon? In particular this tiny fuse?

[budm]

Re: Samsung UN55B7000WF - backlight present but no image

Yes. So you have bad fuse or the load connected to the fuse is bad and causes the fuse to blow, the shorts may not show up when measuring the resistance on that end of the fuse that show 131mV and ground due to other active device that is not turn on until power is applied. Do you know how to use your meter current measuring mode (10A DC mode)?

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

Yes. So you have bad fuse or the load connected to the fuse is bad and causes the fuse to blow, the shorts may not show up when measuring the resistance on that end of the fuse that show 131mV and ground due to other active device that is not turn on until power is applied. Do you know how to use your meter current measuring mode (10A DC mode)?

Budm...you are referring to the 10A Max slot on my meter? I know how to set it up but am not familiar with using it. Again, very little experience using a multimeter except for high school science class back i the 80's. I do't mind probing around the tcon or main board, but would not be comfortable examining the powerboard with the TV plugged in.

[budm]

Re: Samsung UN55B7000WF - backlight present but no image

I think the best way right now is to get a 4A fuse from Radio Shack or car fuse, then solder the wires to each end of the fuse, the other end of the wires will be soldered to each end of the blown fuse, no need to remove the old fuse, wrap the new fuse in electrical tape, and see if it will function.
BTW, look at the LCD panel and find the sticker that will show the model number of the panel so we look up the spec sheet for it.

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

I think the best way right now is to get a 4A fuse from Radio Shack or car fuse, then solder the wires to each end of the fuse, the other end of the wires will be soldered to each end of the blown fuse, no need to remove the old fuse, wrap the new fuse in electrical tape, and see if it will function.
BTW, look at the LCD panel and find the sticker that will show the model number of the panel so we look up the spec sheet for it.

I should be able to do that.

Here is the label info too

thank you all for your help and input

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

I think the best way right now is to get a 4A fuse from Radio Shack or car fuse, then solder the wires to each end of the fuse, the other end of the wires will be soldered to each end of the blown fuse, no need to remove the old fuse, wrap the new fuse in electrical tape, and see if it will function.
BTW, look at the LCD panel and find the sticker that will show the model number of the panel so we look up the spec sheet for it.

Well...the issue can now be confirmed that it was this tiny "N" fuse that was faulty. I built a separate 4A fuse and soldered it to either side of the open fuse. I now have an image!! However...when I turned the TV for the first time after creating the fix, there were a couple sparks as a different component on the right side of the board fried (I was not able to see any obvious damage, but I saw the spark and smelled the burnt component). Regardless...the display continued to work perfectly and and no other issue was noticeable. I kept he display going for about 30 minutes before shutting down and unplugging. Without knowing what blew, or it's significance, I will just purchase a new TCon board so I can rest knowing my house isn't going to burn down.

[selldoor]

Re: Samsung UN55B7000WF - backlight present but no image

Maybe whatever sparked - dry joint or whatever was what blew the original fuse
the one you have in now is perhaps more forgiving.
I think new board is a wise decision - if nothing else saves you having to dismantle it all again.
Make certain you get the exact same board as per the barcode label and
try and get the seller to confirm it will work with your panel.
Quote them the info from the panel label.
Let us know how you go on.

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

Maybe whatever sparked - dry joint or whatever was what blew the original fuse
the one you have in now is perhaps more forgiving.
I think new board is a wise decision - if nothing else saves you having to dismantle it all again.
Make certain you get the exact same board as per the barcode label and
try and get the seller to confirm it will work with your panel.
Quote them the info from the panel label.
Let us know how you go on.

Board number is 35-D043524 per the label on the board itself. Interestingly all the boards with the same number I have found online are for a different model of this TV (UN55B6000).

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

Forum experts...any thoughts on the T-Con board number being referenced for a different model of TV? There are certainly a lot of boards out there that say they're for the UN55B7000, but literally everything I've found with the part number printed on the label for my board is for the UN55B6000. Any chance they put the wrong board in at the manufacturer and that is why the fuse crapped out?

[selldoor]

Re: Samsung UN55B7000WF - backlight present but no image

No Expert but I have looked and find the same - however the other Tcons that fit yours
also appear to fit the 6000 model so on that basis yours should fit both as well.

Personally I would just fit or have someone fit the correct fuse - they do blow just out of old age - bit of a power surge and exposure to heat.

[northwestdad]

Re: Samsung UN55B7000WF - backlight present but no image

No Expert but I have looked and find the same - however the other Tcons that fit yours
also appear to fit the 6000 model so on that basis yours should fit both as well.

Personally I would just fit or have someone fit the correct fuse - they do blow just out of old age - bit of a power surge and exposure to heat.

I'm finding these boards online for anywhere from $45 - $95 USD. I feel I would have to pay someone at least that much just to replace the fuse, or spend twice as much on higher quality soldering equipment to do it myself, so simply buying a working board is something I don't have a problem doing, especially when considering I was given the TV for free.

Also...I got into the service menu to see how many hours of use it had and was shocked that it has nearly 14,000 hours. This was purchased by my company in 2011 and mounted in the conference room and was hardly ever used except to hook up to a laptop for large screen presentations 1-2 times per week. I suspect that since the screen would go blank after being disconnected from the laptop that folks forgot to turn the TV off and it would remain powered on for days or weeks on end.