Samsung LE37A556P1F Flashing red light

[py3m4n]

Re: Samsung LE37A556P1F Flashing red light

I have had a snoop about and it doesn't look like the eeprom is a problem on that series, from what I can glean the eeprom is capable of automatically resetting itself. Looks likes it's only a problem on previous years units.

[TechAMP]

Re: Samsung LE37M86BD wont turn the screen!

Hookup a DVD source playing a movie. Plug it into the TV. In dark room, ..

1) ..can you see the DVD playing without the backlight on? nothing
Try shining a flashlight on it. didn't help.. Is there sound? Yes

2) Circled in red are some ICs. What is the part number?
P2804ND5G, N- & P-Channel Trans.

3) circled in yellow are SMD fuses. 3A/32V, all are OK
Is it a good idea if I disconnect all inverter channels by disoldering those 3A fuses, and test only one ch. at a time?

On PSU board, there is no pulses at " PMW & ADIM". Is that normal. There are no pulses at all on the Inverter board, when the TV is ON!

I made & noted down som measurements on the boards for your info!

[TechAMP]

Re: Samsung LE37A556P1F Flashing red light

My response is to Jasgriff. Why has TechAMP ambushed Jasgriffs thread, lol.

Sorry. I'm new at this forum. Couldn't fix the problems with the "Making new post, Editing / deleting" wrong messages. I'll try to make a new thread next tim.
Thank U for your patience.

[retiredcaps]

Re: Samsung LE37M86BD wont turn the screen!

2) Circled in red are some ICs. What is the part number?
P2804ND5G, N- & P-Channel Trans.

1) Here is the datasheet for

http://pdf1.alldatasheet.com/datashe...P2804ND5G.html

Refer to the diagram for pinouts.

2) Measure the resistance between S1-G1, S1-D1, D1-G1, S2-G2, S2-D2, D2-G2 for all chips. You can do this in circuit and report all readings. Any reading under 30 ohms suggest the mosfet might be shorted and warrants desoldering and verifying the reading out of circuit.

3) PS. Since you are getting sound, the power LED on, and a brief flash of backlight, this narrows down the problem to the inverter board.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Forgot to bring home my camera!

Thought I would list the pins on Connector 3.

1 P8
2 N/C
3 S8
4 GND
5 GND
6 GND
7 12.5v
8 12.5v
9 GND
10 GND
11 GND
12 GND
13 5.3v
14 5.3v
15 5.3v
16 5.3v
17 GND
18 GND
19 12v
20 GND
21 12v
22 12v
23 N/C
24 N/C

Whats the best way of testing these pins? I have tried to do it on the power board with the cable not connected to the mainboard but i cannot read anything. I assume that the power board knows that the cable is not connected?

With only Connector 3 connected the mainboard is getting power as I can measure voltage across some of the Ic's I will write my finding down shortly.

[budm]

Re: Samsung LE37A556P1F Flashing red light

While testing connector 1 with connector 2 and 3 plugged into the mainboard I get the following...

Adim = 0v
BL = 0.1v

"This is in the on state where if connector 1 was hooked up it would give me a completely blank picture.

With connector 1 and 3 connected I tested connector 2 on the mainboard.

BLU = 0.1v
Admin = 0v
PWM = 3.2v

Ta for the help with the pins this will help when I am do a little more testing tonight."

Well per your voltage measurement, you do not have the BL_ON feeding the power supply board which is fed into Connector2 by the main board, and this signal flows into connector 2 right through to connector 1 BL_ON pin which is then sent it out to the inverter board. You should be able to trace out this BL wire from power supply board back the main board connector.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

I have traced BLU back to the mainboard and here is a pic of what it look like and how I tested it.

GND to BLU = 0.1v
GND to Point 1 = 0.1v
GND to Point 2 = 5.2v
GND to Point 3 = 5.2v

[budm]

Re: Samsung LE37A556P1F Flashing red light

Can you please post the picture without the marking so I can see if the trace is connected to the Collector pin ( middle pin the small 3-pin device) through the resistor?
Thanks

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Can you please post the picture without the marking so I can see if the trace is connected to the Collector pin ( middle pin the small 3-pin device) through the resistor?
Thanks

Sure....

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

I actually ordered a second mainboard for this set which turned out to be a slightly different model.

It doesnt have the connector or the resistor attached which allows me to test if that pin connects to the collector through the resitor and it definitely does.

[budm]

Re: Samsung LE37A556P1F Flashing red light

It does not sound like you order the correct PCB assembly for this model!
By the way, I keep getting confuse between your original post and your pictures with the TECHAMP posting on your original post, I wish he will post on the new post instead so I can answering to the right person since they are not the same model, as you can see his main board picture does not have or use that small connector like your new board, but your old board uses/needs that small connector.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Hi the original board that came with this TV is still in place.

I ordered the second board as sold as seen for £6 knowing that it might not be the right one but I thought it was worth a look. It something I can possibly use for parts or testing my soldering skills / or lack of.

I know his posts are confusing. He made a mistake making his first one.

So that resistor seems to be dropping 5v over it?

Should I not be getting sound regardless of this pin not getting its 5v?

[budm]

Re: Samsung LE37A556P1F Flashing red light

OK, please see the attached PDF and verify if that BL_ON is really the BL_ON PIN, also verify the "E" and "B' voltage reading of that transistor. I think the transistor is on right now, it is a Common Emitter connection setup for this transistor.

[budm]

Re: Samsung LE37A556P1F Flashing red light

You are correct, you should get the sound if you do have the 12vdc power supply section working as you have indicated.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

1, This end of the resistor connects to the collector of Q6101 - YES
2, BL_ON Signal OUT? - Checked again and it definitely that pin the one next to it is ADIM which connects to the second resistor from the left of the next group of 4 resistors.
3, Measure B and E - Using the negative probe on E and the positive on B this gives me 0.7V does this mean its connected to ground?

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

You are correct, you should get the sound if you do have the 12vdc power supply section working as you have indicated.

Connector 1 is giving off 12v but I cant check all of the pins on Connector 3. I know that its definitely giving the board power as the optical output lights up and there is power across off of the voltage regulators.

[budm]

Re: Samsung LE37A556P1F Flashing red light

That mean that transistor is being told to turn on by the processor, that is the why the Collect voltage is low and that is why you are getting 0.1v at the BL_LINE.
You can turn that transistor off by connecting a 100 Ohms between the "E" and "B' pins of the transistor, then you should see BL goes high toward 5VDC, if it does not go up, then it may have "E" to "C' shorted out. You can try Ohming out "E" and "C" first if you want.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

I connected Connector 2 and 3 then used the multimeter to check continuity between the collector of Q6101 and the BL pin of connector 1 and as you say they do link through.

[budm]

Re: Samsung LE37A556P1F Flashing red light

By the way, since a lot of TV use Common Emitter circuit to drive the BL_ON or PS_ON signal, if you use the 3.3k Ohm resistor connect to 5vdc and PS_ON or BL_ON, you will not be to bring that signal up if the transistor is already on, the transistor will load down the 3.3k resistor, that is why you need to disconnect the cable attached to the main board to manually turn on the P.S, or the Inverter board.

[budm]

Re: Samsung LE37A556P1F Flashing red light

Try shorting out that Base and the Emitter with the 100 Ohms and see if the BL is ON.