Samsung LN32B360C5DXZA Sound OK, No Video

[Dgtech]

I'm trying to fix this one I got for about $30.

This set was working fine for about a day after I got it. Now it's got sound but no picture.

I changed 2 caps on the inverter board just for the heck of it. - No help
I found another thread on this set. That TV had a bad Tcon connector from water damage. I haven't checked this yet. I just found that thread. I'll do that next.

Here is a schematic, the voltages I got off of the boad, and a pic of the unit.

My camera is not doing what I want it to do right now, I dont know why. Sorry for the bad pic.

[hijodalgo]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

I think there is a problem with some Diodes,please check,,you must change them..

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

I checked the three diodes. All three check out fine. Two are the same and the one on the left (closest to transformer) is a different type, but all check ok.

[PlainBill]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Your description is ambiguous. Is the problem no backlight, or no video signal? The fact you replaced caps on the inverter leads me to think you feel you have an inverter issue.

Note this thread, and the posts by wizard, particularly about the 'lot of bad diodes' and 'prevent backlight from turning on'.

PlainBill

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Sorry, I was in a rush.

The problem is that whenever the set is cold, it comes on for a little bit (about 30 secs) and then the backlights shut off. Whenever warmed up a bit, the backlights never come on. The sound is fine.

I got this from a guy for $30. He said that it had problems. I came home and it ran for about a day with no problems. The second day it finally died. I took some readings on/off and let it sit for another day. It then came on and worked fine. I wanted to make it fail so I kept re-cycling power to it to see if it would. Sure enough, on the 4th time, and times after, no backlights.

I will find my flashlight soon and check for image. In the meantime, I have the 5V (inverter on/off) toggle as a clue as well as the power LED blinking 5 times. My voltage readings (in red font) from the power/inverter board are above in pic 2.

[Wizard]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

This is one of these models with bad fat diode (one of 3 fat diodes), will read some ohms both ways (leaky) on ohm range. Not diode test.

Otherwise another inverter/power supply board.

Cheers, Wizard

[PlainBill]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Sorry, I was in a rush.

The problem is that whenever the set is cold, it comes on for a little bit (about 30 secs) and then the backlights shut off. Whenever warmed up a bit, the backlights never come on. The sound is fine.

I got this from a guy for $30. He said that it had problems. I came home and it ran for about a day with no problems. The second day it finally died. I took some readings on/off and let it sit for another day. It then came on and worked fine. I wanted to make it fail so I kept re-cycling power to it to see if it would. Sure enough, on the 4th time, and times after, no backlights.

I will find my flashlight soon and check for image. In the meantime, I have the 5V (inverter on/off) toggle as a clue as well as the power LED blinking 5 times. My voltage readings (in red font) from the power/inverter board are above in pic 2.

Some of those voltages look strange. I hadn't looked at them before because I am philosophically opposed to downloading a 1.7 meg BMP when a 76K JPG will do the job. Note the difference.

PlainBill

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Bill, you have to let loose the 56K modem download speed every once in a while. I'll meant to make that into a JPG instead of BMP. Sorry again. My company has sent me to school for the week learning AB PLC 5000 programming so my brain is toast.

Yes Wiz, the tests I did on the diodes was the Diode test. I will desolder them from the board ASAP and check them as you suggested.

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Ok, now I have more questions than answers.

Using both of my meters, I measured the two diodes. Once on diode test and once with resistances. Heres what I got:

Forward Resistances
............Fluke 26III.............Fluke 179

DP810 - - 2.09Meg - - - - - - 292K

DP805 - - 1.35Meg - - - - - - 222K

DP804 - - 2.03Meg - - - - - - 284K

All reverse show infinite as it should.

I dont really question the diodes as they all measure the same. Diode check shows .4 and .5 voltages as it should. These are all out of circuit measuremets.

[fastvideo]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

I have a BN44-00260b board that has the schematic except the output pins.

UI801 has no drive signal output. replaced a working SEM2006 but no drive still.

Replace the complete board cost me almost $100.00 and I have drive signal , TV works now. I would like to fix the defective board.

[fastvideo]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

I have a BN44-00260b board that has the schematic except the output pins.

UI801 has no drive signal output. replaced a working SEM2006 but no drive still.

Replace the complete board cost me almost $100.00 and I have drive signal , TV works now. I would like to fix the defective board.

13v and 5.3v measure good, assuming power supply section is good.
back light drive signal is missing.

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

I'm glad you got your set working.

Do you have a 4V 150 Hz square wave out of E-PWM?

Somthing that has me concerned is the VCC for UI801 (SEM2006). I have 13 volts going to it as well. I dont know if this is too low for this chip or not. The datasheet below says this chip has a MAXIMUM of 36VDC for the VCC.

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Here is more of what I am noticing with mine:

All voltages seem OK whenever the board is powered up without the processor board being plugged in. It's as if the processor board is somehow telling the power board to shut down. The 5VDC on the connector is solid, but whenever the other board is plugged into this one via the ribbon cable, it goes from 5VDC to 0 four to five times and then quits.

[fastvideo]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Replaced the board alone and tv works, so the problem must be the BN44 board.

Problem would be somewhere between how UB802 control INV_UVLO.
InverterON/OFF is not staying high after power on.

With the AC live voltage in one board is the worst design for repair. I stop at this point since all component is located underneath.

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

Thanks for the info. You are correct, bad design indeed. I also love how they plugged the board into the side connector instead of having CCFL connectors on the board. Must have been some genius that came up with that.

Sounds like you had the same exact failure I had. I wonder if that INV_UVLO voltage is either too high or too low and the set is sensing that. There is some type of sensing circuit that is shutting this down.
You probably dont want to mess with your working set but it would be nice to get a measurement on a working set for INV_UVLO.

[Wizard]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

No. This is result of increased reliability and improved efficient power usage through fewer components and fewer wirings.

Cost is not that expensive to replace the board and there is a exchange core fee. Call up the samsung authorized shop give full model code and version from your small sticker on left as you are looking at back. Should not be more than 100 like other did.

You had did enough check to confirm that there is deeper problem with the board. Not very often happens, I did not see many of these models to show how good they are.

Cheers, Wizard

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

The manufacture date for this set was December of 2009. You may start to see them as they are failing short of making their 2 year anniversary. VERY SAD.

I'm going to take a small risk on replacing a chip that seems logical to replace for the hell of it.

The chip is UM801S (ICE3BR0665J) The cost of one chip is $3.60. I'll report back the result.The datasheet is available here:


https://cdn.badcaps-static.com/pdfs/...4da0f4fb93.pdf

[Wizard]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

If that was true, we would be fixing lot of those. That's not true Dgtech. I'm sorry that you was unlucky one with a 32" LCD. Get it fixed anyway. May need whole board if you cannot troubleshoot with scope. Have you confirmed finding no waveforms from the IC?

Most of the sequence goes this way: Microcontroller turns on main power supply in turn kicks start the PFC IC, then finally the hot side lamp inverter starts up.

Cheers, Wizard

[Dgtech]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

One way or another I'll figure it out - theres really no rush to it. I never go as far as to replace a whole board. Right now I'm just waiting for parts to come. Digikey is usually fast. Until then, I'll throw the next set back on the workbench. Once I do get this one working, I'll post what the fix was. Sounds like Fastvideo had the same problem and maybe there will be more.

[fastvideo]

Re: Samsung LN32B360C5DXZA Sound OK, No Video

I am not sure if we can try to force UI801 SEM2006, Pin 16 On manually and how?