samsung 32 ln32b360c5d no power no indicator

[fcisolutions]

Re: samsung 32 ln32b360c5d no power no indicator

Mine is very similar to Buowulf. Same power supply as we are talking about and isolated from the main and lamps.

I thought I had a problem with ZM804 zener but after removing the diode and testing it, I'm not so sure.

Out of circuit it tests .667 with my red meter probe on the anode. I get OL with the red lead on the cathode.

In the circuit I'm getting an indication of a short and then voltage climbs to .667v with the red lead on the anode. With the red lead on the cathode I get .7v and it climbs to 2v and then I get OL. Then when I reverse the leads I get the short and voltage again climbs to .667. Is this normal?


Filter cap 166v

Readings from CN802 (main output power connector)
Pin
1-gnd
2-sync -Starts at 0 (sometimes stable at 0) and creeps to 0.5v then to 0v
3-Det-5v -- 0.5v
4-E-PWM -- 0.5v
5-Inverter on/off varies from around 4.5v to 5v
6-13v(m) around 11.5-13v on and off
7-13v(m) around 11.5-13v on and off
8-gnd
9-5.3v varies from around 4.5v up to 5v
10-5.3v varies from around 4.5v up to 5v
11-gnd
12-gnd
13-13v(s) varies 11.5-13v
14-gnd
15-stby 5.3v varies from around 4.5v up to 5v
16-Pwr on/off varies around 0.7v

[fcisolutions]

Re: samsung 32 ln32b360c5d no power no indicator

I should also note that I did change ZM804 with a zener diode that I scavenged from another board that tested good out of circuit but behaves the same way as the original.

[Acton-Hilton]

Re: samsung 32 ln32b360c5d no power no indicator

Thanks for all the info, I have a similar UK LE32-B550S5W, board no: BN44-00261B
There is no backlight, apart from a brief flash. In this case one of the Transformers (T1801) is obviously burnt. Are replacements for the Transformer, available?

[diif]

Re: samsung 32 ln32b360c5d no power no indicator

Thanks for all the info, I have a similar UK LE32-B550S5W, board no: BN44-00261B
There is no backlight, apart from a brief flash. In this case one of the Transformers (T1801) is obviously burnt. Are replacements for the Transformer, available?

Yes. http://www.ebay.com/itm/OEM-New-Tran...-/172452643466

[Acton-Hilton]

Re: samsung 32 ln32b360c5d no power no indicator

Yes. http://www.ebay.com/itm/OEM-New-Tran...-/172452643466

Thanks, another star is born!!

[alh84001]

Re: samsung 32 ln32b360c5d no power no indicator

Hi all. I'm a complete n00b when it comes to this, so bear with me.

My father has a Samsung LE32B350 TV with a BN44-00289B power supply inverter. It started going crazy - turning on and off by itself, and then after a week or two it went completely dead.

I took the board out connected it to mains, and got the following DC voltage readings from the CN802 pins with black probe on pin 16:
1 - 0,77
2 - 5,20
3 - 0,00
4 - 13,19
5 - 0,00
6 - 0,00
7 - 5,20
8 - 5,20
9 - 0,00
10 - 13,19
11 - 13,19
12 - 2,86
13 - 4,82
14 - 0,43
15 - 0,00

Also, I measured DC voltage on CP815 constantly shifting in the 393-395V range.

Does this mean this board is OK, or could it still be faulty diodes? If yes, then I need to figure out how to test diodes with my cheap instrument. (Any pointer to which diodes I can get instead of the ones on the board are welcome; I don't know if there is anything, e.g. amperage, that I need to watch out for when getting them)

Thanks!

[alh84001]

Re: samsung 32 ln32b360c5d no power no indicator

Here is also a picture of the board. Area around those fishy diodes is suspiciously darker than the rest of the board, as well as the area to the top of the leftmost cooler in the picture. Bottom of the board has no visible damage anywhere. Top of the CM852 (1200uF, 10V) capacitor looks slightly convex (other capacitor tops are concave), but it doesn't look blown to me.

[vinceroger69]

Re: samsung 32 ln32b360c5d no power no indicator

Here is also a picture of the board. Area around those fishy diodes is suspiciously darker than the rest of the board, as well as the area to the top of the leftmost cooler in the picture. Bottom of the board has no visible damage anywhere. Top of the CM852 (1200uF, 10V) capacitor looks slightly convex (other capacitor tops are concave), but it doesn't look blown to me.

That one capacitor does look bad as has slight bulging top but as theirs only 11 small capacitors i would first start by changing them all as capacitors can fail with bad uf ratings and also bad esr .

[budm]

Re: samsung 32 ln32b360c5d no power no indicator

You should have put the pin label for each pin to make it easy for us to know which pin has correct Voltage.
"14 - 0,43" That is the DET_5V which is the inverter error signal pin, it should be high (>2.5V) if the inverter section is OK.
But since you have bad cap CM852 (CM854 is also part of the STBY filtering) which is for the 5VSTBY filter so the main board is probably not getting good 5VDC feeding it.
You should at least replace those caps in that cold side of the power supply.
Pictures provided by shopjimmy.

[alh84001]

Re: samsung 32 ln32b360c5d no power no indicator

Thanks guys on all the help. I'll go out tomorrow and get the caps for it.

Two questions though:
1) What is the cold and what is the hot part of the power supply? I mean in general? in this board I presume that would mean exchanging those seven caps in the lower left in my picture?
2) Can I put higher voltage caps in place of the lower ones? E.g. I have a 1200uF 35V one available, and CM852 is 1200uF 10V while CM876 is 1200uF 25V?

Edit: Success! I replaced that single cap, and now it turns on. Thank you once more!

[budm]

Re: samsung 32 ln32b360c5d no power no indicator

No need to go higher Voltage rating caps, just use good brands LOW ESR 105c caps such as PANASONIC FM/FR/FC.

[vinceroger69]

Re: samsung 32 ln32b360c5d no power no indicator

the hot side of the psu is where the mains power goes in it usually has a white band around that area so you know its the mains voltage area also risk of mains shock etc also when working in that area we use the large capacitor negative leg as a ground when testing voltages in that area the cold side is the other side of the white box area and we can use a screw hole as a ground to take measurements im sure budm etc can it enplane it better, glad you have got the tv working but remember all the other capacitors are probably the same age so fail shortly so best replace them all in one go for a lasting repair.

[SumeshAK]

Re: samsung 32 ln32b360c5d no power no indicator

I am having the same PSU for the LCD TV.
5.3 stby voltage is not coming.
Voltage on the other tapping of the outpu transformer is coming.
I get 15V just before the switching FET in the secondary.
Please help me to identify the fault.
No sign of burn, fuses are in tact.
My supply voltage is 230V connected via a 100W series bulb.

Kindly help!.
Thanks and regards,
Sumesh

[nomoresonys]

Re: samsung 32 ln32b360c5d no power no indicator

Thread has quite a few posts sumeshak, what exactly is are the symptom/s? Did you check all the diodes?

[Howard_Woodard]

Re: samsung 32 ln32b360c5d no power no indicator

I have a Samsung LN32B360C5D set that has a mind of its own. Its like the little girl who when she was good she was very, very good but when she was bad she was horrible. If it hasn't been plugged in for a while -- a few hours to a few days -- it acts like it should. ...for a while... The standby light comes on and it responds correctly to all the side panel buttons as well as the remote control and has a great picture. However, either after turning it off or after it has been on 10-15 minutes, when you turn it back on it is in a 28-29 second perpetual loop -- power-on chime, 1.5-2 sec backlights on, 28-29 seconds backlight goes off, 1.5-2 seconds later you hear the power-on chimes and it just repeats. Once it starts looping none of the controls, button or IR, have any effect -- it just loops on its own and will start looping as soon as the power cord is plugged in.

All the voltages look good. In fact, even when it is not responding to the buttons and IR they are still sending correct signals to the main board. The only difference that correllates to when it works and when it doesn't is the pin coming from the chip under the finned heat sink on the main board -- I haven't been able to find a schematic of the main board -- that switches on the pull-down transistor Q302 for pin 1 (power on/off) works correctly when the set is working correctly but just sits at 0V when it isn't. 0V leaves the pull-down off letting pin one go high which is the on signal.

I have an oscilloscope but don't really have the correct probes for looking at ripple noise on a switching PSU so I can't say that the power rails are completely clean. Just in case I re-capped the whole thing with capacitors of the correct voltage, capacitance and low ESR but it made zero difference in the symptoms. I do see the high voltage frequency/duty cycle change when the power-on chimes and then when the backlight comes on and again when the backlight goes off. No way for me to know which comes first but since the PSU uses PWM it appears that it is working correctly and these are just the changes that result from feedback from the various loads but probably primarily the inverter load.

Since the voltages and inputs look fine, just the one output line that doesn't always seem to be working, I'm thinking of removing the glued-on heat sink and reflowing the solder on the chip that contols that on/off signal but before I do I thought I would run this by folks to see if there might be some better approach. I would love to be able to find a schematic of the main board but either my google skills are insufficient or there just simply isn't one online anywhere.

Thanks in advance for whatever help and advice you might offer,

Howard

[Howard_Woodard]

Re: samsung 32 ln32b360c5d no power no indicator

I hope this is ok. I don't see a way to delete my post so I'm gonna leave it here but I think my issue is different enough that I should start a new thread. Hopefully the folks familiar with this TV are still around and can help me.

Howard
Redmond, WA

[Soldiaz]

Re: samsung 32 ln32b360c5d no power no indicator

I am new to forum but cannot open new thread so I try here. Inown Samsung LE37B650T2P which shuts down randomly Black screen no Red power light. After while Red Power light again and I can turn on for while.

I read I supposed to Check caps.

Hopefully anyone can assist me? Any help appreciate

[nomoresonys]

Re: samsung 32 ln32b360c5d no power no indicator

it's an old tv. I would replace those 8 electrolytic caps right there by the connector first, might save a whole lot of troubleshooting if that is just the problem.

[nomoresonys]

Re: samsung 32 ln32b360c5d no power no indicator

also look the cable from powerboard to mainboard over real good, check for burn marks, can check each wire for continuity.