Samsung LE37A556P1F Flashing red light

[Scenic]

Re: Samsung LE37A556P1F Flashing red light

If that's the case, there's a matching board available on ebay UK for 27 pounds incl. shipping

ebay # is 270923709503
(copy & paste that number into the search)

There are a few more but the one above happens to be the cheapest one and has roughly 1 day left.


edit: now that I look at the pics, that board looks VERY similar to the one in my Samsung LE40A536, which also had mainboard problems (restarted every 10-15secs, nothing seemed to fix it). Got a new board and everything worked just fine.

Seems like the A-series (LExxAxxx .. the "A" indicating the year 2008) Samsung LCDs have mainboard probs quite often..

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

In my case (BN44-00199A PSU from a 40" LCD), the PSU had a split 12V (actually 13V) output, on mine labelled 13Vm and 13Vs.

13Vm = 13V mainboard voltage ("general purpose" .. to be stepped down via LDO's mostly)
13Vs = 13V exclusively for the sound part (amplifier)

the main 13V rail also was considerably more beefy (3.xA) compared to the sound one (1.xA)

You might find the same setup on your PSU board, just with a voltage missing.

Also after a bit of googling I found out what that IC in your attached picture is.
Guess what? The NTP-3100 series is a digital amplifier IC made by "Neo Fidelity Inc. Korea"

Of course, no datasheets or anything available on their useless website.
http://www.neofidelity.com/eng/techn...digital-tv.php

I'd say check the voltages on the PSU connector going to the mainboard. Should be silkscreened which pin is what (either on the front or the back of the PSU board)

Ta I have now checked all of the pins on the big connector which connects the PSU and the mainboard. They all seem to match what they should according to the diagram on the top of the board.

With no sound and no picture the mainboard must be completely goosed.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Do you get 12vdc on either end of the BD2107 and ground (one lead of the meter to GND, and another lead for probing either end of the BD2107)? I thkink this BD is the line filter. So you do have the service manual?

Checked it properly and there does appear to be the right voltage across BD2107.

It was just a 4 page trouble shooting guide which I cannot seem to find now.

[Scenic]

Re: Samsung LE37A556P1F Flashing red light

In my case (BN44-00199A PSU from a 40" LCD), the PSU had a split 12V (actually 13V) output, on mine labelled 13Vm and 13Vs.

13Vm = 13V mainboard voltage ("general purpose" .. to be stepped down via LDO's mostly)
13Vs = 13V exclusively for the sound part (amplifier)

the main 13V rail also was considerably more beefy (3.xA) compared to the sound one (1.xA)

You might find the same setup on your PSU board, just with a voltage missing.

Also after a bit of googling I found out what that IC in your attached picture is.
Guess what? The NTP-3100 series is a digital amplifier IC made by "Neo Fidelity Inc. Korea"

Of course, no datasheets or anything available on their useless website.
http://www.neofidelity.com/eng/techn...digital-tv.php

I'd say check the voltages on the PSU connector going to the mainboard. Should be silkscreened which pin is what (either on the front or the back of the PSU board)

[budm]

Re: Samsung LE37A556P1F Flashing red light

Do you get 12vdc on either end of the BD2107 and ground (one lead of the meter to GND, and another lead for probing either end of the BD2107)? I thkink this BD is the line filter. So you do have the service manual?

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

I have looked for a service manual and one of the troubleshooting tests was to check BD2107 which should have 12v running across it. I have checked this on my board and there is nothing running across it. This is supposed to have something to do with the sound. Am i right in thinking that the board may be getting the lower voltages but not the higher ones maybe?

Whats the best way of checking the board for the 12v supply?

[budm]

Re: Samsung LE37A556P1F Flashing red light

OK, your DC supply seems to be OK, next step will involve traing out Main board control signals which will be real hard without the service manual, even if you trace it out back to the CPU pin, there is no easy way to verify is the CPU is good or not. I really do not have any more suggestion on this.
Bad regulator will either put out nothing, too high, or to low voltages.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Tried the second board and the those Adjustable regulators are giving off the same readings as the original board.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Looking at that calculation I should have been getting 1.5v and 1.7v.

When these regulators go do they make any sort of a noise as when I got the TV it would also make a high pitched noise which sounded like it may have come from one of the components when it did?

I have just thought that if I wire up the second board I can measure the regulators there and see if they are any different too.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Yeah that's a different way of working it out il have a look at that now.

[budm]

Re: Samsung LE37A556P1F Flashing red light

I think you are missing some value in the calculation (the 1.25v ref), see page 8 for calculation which might be clearer than the LM1117XXX SPEC SHEET.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Just realised that there are more regulators on the underside of the board

There are another 3 which will be quite difficult to test without taking off off both boards and setting them up away from the tv?

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

The one with the adjustable output using the resistors at the adjustable pin, there is a note in the spec sheet on how to set the out put voltage by calculating the value of the two resistors. You will have to Ohm out the two resistor and see if you put those value into the formula to see what it should have at the output.

Ok I have tested the first set and these are the results and my calculations do they seem correct?

The second set of readings are attached and they seem to be alot closer to what I would be expecting to find.

[budm]

Re: Samsung LE37A556P1F Flashing red light

The one with the adjustable output using the resistors at the adjustable pin, there is a note in the spec sheet on how to set the out put voltage by calculating the value of the two resistors. You will have to Ohm out the two resistor and see if you put those value into the formula to see what it should have at the output.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Ok thats all of the readings from the voltage regulators listed.

All seem to be performing ok.

Not sure how to test what the variable regulators should actually be outputting though?

[budm]

Re: Samsung LE37A556P1F Flashing red light

I still do not know which IC will be using 1.5v for VCC, the cpu will more likely to use the 1.8v. But we will find out if he can find what went out on the main board.

[Scenic]

Re: Samsung LE37A556P1F Flashing red light

No prob. It's a weirdo VR though.. Apparently it's a "standard" 78xx series voltage regulator, but with a completely oddball 1.5V output voltage.
(the lowest the actual standard/jellybean 78xx's go to is 5V)

I thought it was 15V too.. but that voltage seemed really odd for a LCD TV mainboard.. so I went digging a bit

[budm]

Re: Samsung LE37A556P1F Flashing red light

scenic, thanks for finding the spec sheet, I should have seen the 0 (ZERO) in front of the 15, which makes sense, thanks.

[Scenic]

Re: Samsung LE37A556P1F Flashing red light

KIA 78D015F: More likely to be the same as LM7805 low drop out type 15V FIXED Regulator

KIA78D015F is a 1.5V voltage regulator. Not 15V.

[budm]

Re: Samsung LE37A556P1F Flashing red light

CH? 17-33 0818BG: More likely to be the same as LM1117 3.3V FIXED Regulator
CH? 17-18 0814BG: More likely to be the same as LM1117 1.8V FIXED Regulator
ch? 1117 0819BG x 2: More likely to be the same as LM1117 Variable Regulator, the voltage will set by two resistor on one of the PIN.
17-25 0807AG: More likely to be the same as LM1117 2.5V FIXED Regulator
KIA 78D015F: More likely to be the same as LM7805 low drop out type 15V FIXED Regulator

So just look up the datasheet for them.