Samsung LE37A556P1F Flashing red light

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Ok

CH? 17-33 0818BG
CH? 17-18 0814BG
ch? 1117 0819BG x 2
17-25 0807AG
KIA 78D015F

Those are the ones I can see on the main board.

[budm]

Re: Samsung LE37A556P1F Flashing red light

They will not be all the same, there should be some kind of marking on those regulators, we need the numbers so we can look up the spec for them.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Well, that main board is not working as far as the BL ON signal, second thing will be that you can now turn on the backlights for the light source, then you should see the pictures on the screen, if not, then you have more problems on the main board beside no BL ON signals. Power supply section on the main board will have to be checked next since it has a bunch of voltage regulators on the main board.

Backlight comes on but the screen has not picture at all.

I can see about 5 voltage regulators on this board. Do you want the readings from all of these along with their model numbers or should they all be the same?

[budm]

Re: Samsung LE37A556P1F Flashing red light

Well, that main board is not working as far as the BL ON signal, second thing will be that you can now turn on the backlights for the light source, then you should see the pictures on the screen, if not, then you have more problems on the main board beside no BL ON signals. Power supply section on the main board will have to be checked next since it has a bunch of voltage regulators on the main board.

[Jasgriff]

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.

Ok I did that with the multimeter and the back light turned on.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

What you can do is to set your meter to DC AMP mode (you know how to do that right) and just connect the probes of the meter to the E and B, that should do it also.

There is a pic of my meter at the beginning of this post I am guessing that the dial need to be at point to the very bottom with the probes in the same place as if i were measuring diodes?

[budm]

Re: Samsung LE37A556P1F Flashing red light

At this point, we want to verify that the transistor is being told to turn on, it should goes off when the TV is turn on, so it sounds like you have main board problem.

[budm]

Re: Samsung LE37A556P1F Flashing red light

The inverter may have Pulled up resistor on it already.

[budm]

Re: Samsung LE37A556P1F Flashing red light

What you can do is to set your meter to DC AMP mode (you know how to do that right) and just connect the probes of the meter to the E and B, that should do it also.

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

Also when Connector 2 is not connected to the mainboard the backlight comes on really bright so how can it do that with no BL_ON signal connected?

[Jasgriff]

Re: Samsung LE37A556P1F Flashing red light

I haven't got any loose resistors here that the moment to try it out I will have to pick some up tomorrow.

Is there anything else I should pick up while i'm at it?

[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.

[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.

[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

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

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.

[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?

[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.

[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.

[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?