Samsung LN-S4051DX High voltages at power connector

[apache23]

Hello. I'm new to troubleshooting TV's and have the apparent dreaded Samsung no-power clicking situation. As I reaad about this issue, I noticed most of the time it was bad caps, so I thought "I can fix those!" and opened up the TV. I found no noticeable bad caps, so I read further and saw where people tested voltages at the power connector and what to do if you found LOW voltages. What I haven't seen is what to do if voltages are too high and that is what I am getting. At my 13 volt pin, I get 18v, but not stable at all. Goes down during the "clicking" cycle and comes back up to 18v. At the 3 12v pins, I get 26v, again, not steady and fluctuating down and back up. At the 5.4v pins, I get 5.4v, not steady and dropping and rising during the clicking cycle. I ordered a new board, which I found on ebay cheap and they have lots of these new btw if anyone needs one. It will arrive today, but I still am curious to what would cause these high voltages. Any info would be appreciated. Thanks!

[nomoresonys]

Re: Samsung LN-S4051DX High voltages at power connector

Inspect your solder joints on the back side of the board, look closely at any component on a heatsink and the transformer/s joints, check youtube if you need to know what a bad/cold joint looks like, check all your diodes with a multimeter too, you can check the diodes before you take the board out, as always BE VERY CAREFUL when working with the powerboard, the HOT side has DEADLY voltages.

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

Inspect your solder joints on the back side of the board, look closely at any component on a heatsink and the transformer/s joints, check youtube if you need to know what a bad/cold joint looks like, check all your diodes with a multimeter too, you can check the diodes before you take the board out, as always BE VERY CAREFUL when working with the powerboard, the HOT side has DEADLY voltages.

I've been looking for a good video that explains how to test the different components, but the ones I have found require desoldering at least 1 lead on diodes and resistors. And I haven't found anything good on how to test transformers or transistors. There is one spot on the board where it has a little browning next to some diodes, but I don't know how to test them. I have a decent multimeter. Not a Fluke, but it's pretty good. Also, there is a kinda high-pitched humming noise coming from I think the transistor near where those diodes and browning of the board are.

[nomoresonys]

Re: Samsung LN-S4051DX High voltages at power connector

Good one to start with: https://www.youtube.com/watch?v=ocqnqmBxiqY

[nomoresonys]

Re: Samsung LN-S4051DX High voltages at power connector

Pretty basic diode testing there, go ahead and test them in circuit with tv power UNPLUGGED, if any test unusual lift a leg and test again: https://www.youtube.com/watch?v=b8gPSKpbXQs

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

Pretty basic diode testing there, go ahead and test them in circuit with tv power UNPLUGGED, if any test unusual lift a leg and test again: https://www.youtube.com/watch?v=b8gPSKpbXQs

Great thanks, I'll check it out. I have the board removed and the TV is ready for the new board coming today. But I still want to figure out what the problem(s) are with this old one. I'm about to fire up that YouTube video now, thanks again!

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

Pretty basic diode testing there, go ahead and test them in circuit with tv power UNPLUGGED, if any test unusual lift a leg and test again: https://www.youtube.com/watch?v=b8gPSKpbXQs

OK, so all 4 diodes near the brown spot tested between 0.397 and 0.401, but I don't know what they are suposed to be. 2 of them have 506 and 209 on them and the other 2 have 506 and 605.

[nomoresonys]

Re: Samsung LN-S4051DX High voltages at power connector

If you reverse your probes you get OL right? most of them will test between .3 and .7.

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

If you reverse your probes you get OL right? most of them will test between .3 and .7.

Yes, I'm getting OL when reversed....and I'm getting very fu*king pissed off trying to find the schematic for this. I have found several sites with the schematic, but so far, only 1 is actually for this TV and it's a .jpg file. Whatever I open the .jpg file with won't let me search the board (like for individual components D1823 for instance) and they won't even let me move around to see the whole schematic!! And the ones that are .pdf files where I can search around and move are for a 55" tv that has a different board!! Very frustrating!! Oh and I did find one tiny diode that reads 0.029.

[nomoresonys]

Re: Samsung LN-S4051DX High voltages at power connector

.029, that seems bad to me, might be your only problem.

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

.029, that seems bad to me, might be your only problem.

The other day I saw this resistor and thought man, that looks fried!But if you look at pics of other boards for this TV, they are also grey like this one. But shouldn't you at least be able to read the numbers on it? Cuz there's nothing on this one and it reads 0.000 both ways the leads are hooked up. And from what I can find on it it's 0.03 ohms.

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

.029, that seems bad to me, might be your only problem.

I just signed up with SCRIBD and downloaded the service manual......WOW! This manual has everything and more! I'm glad I found this site, it looks like they have millions of documents.

[budm]

Re: Samsung LN-S4051DX High voltages at power connector

The other day I saw this resistor and thought man, that looks fried!But if you look at pics of other boards for this TV, they are also grey like this one. But shouldn't you at least be able to read the numbers on it? Cuz there's nothing on this one and it reads 0.000 both ways the leads are hooked up. And from what I can find on it it's 0.03 ohms.

That black resistor RM808 should be <1 Ohm if you set you meter to 200 Ohm scale, so not likely to have any thing wrong with that resistor. If the diode is tested bad then you need to test it off the board or at least lift one leg off the board, the diode may be connected in parallel with the other parts.
We need the Voltage reading of the power supply board connector that goes to the main board, each pin has label to tell you what they are so make sure to report the readings by putting down the pin name and follow by the Voltage reading for each pin so we can easily see if they are correct or not, they are important data so make sure to report them in the format as requested.
BTW, we need to see good clear straight shots of your boards and also the whole backside of the TV showing all the boards.
What is the power supply board P/N? BN44-??????

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

That black resistor RM808 should be <1 Ohm if you set you meter to 200 Ohm scale, so not likely to have any thing wrong with that resistor. If the diode is tested bad then you need to test it off the board or at least lift one leg off the board, the diode may be connected in parallel with the other parts.

My meter just has AUTO, can't set it to a certain ohm setting range. I found the service manual on SCRIBD and it's a manual for 6 different models similar to mine. It has so much info it's crazy! BUT! In it's list of every part on all the different boards, it doesn't have RM808 or DB803, which tested to 0.029. It doesn't have other components either, so do they maybe list them different in these manuals? Like just R808 instead of RM808? I know it has to be in there somewhere, because it has like ......1,000 or maybe more parts. I wish I could somehow send you the manual. Also, it has a bunch of schematics, but only 1 power board schematic (that I found anyway) and it's for a different TV. Seems strange that the manual has so many fine details, but wouldn't have the PB schematic.

[budm]

Re: Samsung LN-S4051DX High voltages at power connector

Resistor usually goes open circuit when it is bad, so doubt that anything is wrong with that resistor.
Please read update my post 13 again and provide the info needed.

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

Resistor usually goes open circuit when it is bad, so doubt that anything is wrong with that resistor.
Please read update my post 13 again and provide the info needed.

OK will do. I just got the new board and it answered some questions. Apparently they revised the board and the service manual has this new one in it. It no longer has those resistors I mentioned. But most everything else is the same, with a few more exceptions. I'm going to try the new board, then I'll check out your links. Thanks alot for you time and knowledge. As I get older I realize more and more how valuable time is!

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

Resistor usually goes open circuit when it is bad, so doubt that anything is wrong with that resistor.
Please read update my post 13 again and provide the info needed.

Just put the new board in and it fired right up! So definitely something on the power board has gone bad. Now if I can only figure out where I put those damn stand bolts...lol.

[nomoresonys]

Re: Samsung LN-S4051DX High voltages at power connector

Did you check that diode on your new board? maybe it's not the same if they revised the board, was just wondering if that diode is the culprit.

[apache23]

Re: Samsung LN-S4051DX High voltages at power connector

Did you check that diode on your new board?

It's not there. It's a revised board and neither of those diodes I mentioned are on it. And this board is the one that it shows in my service guide, which is why I couldn't find those diodes by searching for them.

[R_J]

Re: Samsung LN-S4051DX High voltages at power connector

DB803 is across the coil of the relay, thats why it checks that way.