Sony XBR-52LX900 BL_ERR

[Nicktronic]

Not so sure about that, it can be hard to tell from pictures but at least a couple of those solders on those transistors look a bit cracked, I would touch up any joints that look different than a good joint, it's pretty simple: https://www.google.com/search?client...h=541&dpr=1.09

Yeah, I think the pics may be misleading you. Unless you can tell what ones you noticed specifically and I'll look at thos closer but I looked over the whole board and they look good.....nothing even questionable...

[Nicktronic]

Can i know how do you measure them? Usually is enough in diode mode every combination of pins, when mounted no one must show a drop near zero volt.

Just followed a standard MOSFET test with them removed and meter in diode mode.

How to Check N-Channel Mosfets 1) Set the DMM to the diode range.

2) Keep the mosfet on a dry wooden table on its metal tab, with the printed side facing you and leads pointed towards you.

3) With a screwdriver or meter probe, short the gate and drain pins of the mosfet. This will initially keep the internal capacitance of the device completely discharged.

4) Now Touch the meter black probe to source and the red probe to drain of the device.

5)You should see an "open" circuit indication on the meter.

6) Now keeping the black probe touched to the source, lift the red probe from drain and touch it to the gate of the mosfet momentarily, and bring it back to the drain of the mosfet.

7) This time the meter will show a short circuit (sorry, not short-circuit rather "continuity).

The results from the point 5 and 7 confirms that the mosfet is OK.

Repeat this procedure many times for proper confirmation.

For repeating the above procedure each time, you will need to reset the MOSFET by shorting the gate and the drain leads using meter probe as explained earlier.

[Davi.p]

so you have a 0v between S and D all the time? if you turn black to D and red to S can you read the internal diode drop (0.5v)? And not least, do you read a short between D and G?

[Nicktronic]

so you have a 0v between S and D all the time? if you turn black to D and red to S can you read the internal diode drop (0.5v)? And not least, do you read a short between D and G?

Not exactly, the steps I listed in post News- Leaking Capacitors Muck up Motherboards are all good except step 6 and 7. After going red to gate and back to drain, they both still read OL not continuity. That indicates bad MOSFETs, no?

[Davi.p]

I see no steps in that post.. test G-D indicates you don't have a short in that junction and you don't have to replace IC that controls mosfet.. let's do things short, touch 3 legs of mosfets with something conductive to discharge them, then in diode mode try every combination of pins, (6 tests) ,no one must show near zero volt. STOP..

[Nicktronic]

I see no steps in that post.. test G-D indicates you don't have a short in that junction and you don't have to replace IC that controls mosfet.. let's do things short, touch 3 legs of mosfets with something conductive to discharge them, then in diode mode try every combination of pins, (6 tests) ,no one must show near zero volt. STOP..

I wrote post News- Leaking Capacitors Muck up Motherboards had the steps. I don't know where that link came from.

[Nicktronic]

What the f...... post 62

[Davi.p]

ok post 62.. ehm.. we are at post #42.. ehehe..

[Nicktronic]

Says 62 on my screen lol......anyway go up a few posts and you'll see the step by step process I took.

[Davi.p]

I already read all posts , if you want to follow my advices lets continue, otherwise i can quit..

[Nicktronic]

I'm not saying I don't want your help, I thought we were just discussing what I've already done....anyway, here it is for reference again:



Just followed a standard MOSFET test with them removed and meter in diode mode.

How to Check N-Channel Mosfets 1) Set the DMM to the diode range.

2) Keep the mosfet on a dry wooden table on its metal tab, with the printed side facing you and leads pointed towards you.

3) With a screwdriver or meter probe, short the gate and drain pins of the mosfet. This will initially keep the internal capacitance of the device completely discharged.

4) Now Touch the meter black probe to source and the red probe to drain of the device.

5)You should see an "open" circuit indication on the meter.

6) Now keeping the black probe touched to the source, lift the red probe from drain and touch it to the gate of the mosfet momentarily, and bring it back to the drain of the mosfet.

7) This time the meter will show a short circuit (sorry, not short-circuit rather "continuity).

The results from the point 5 and 7 confirms that the mosfet is OK.

Repeat this procedure many times for proper confirmation.

For repeating the above procedure each time, you will need to reset the MOSFET by shorting the gate and the drain leads using meter probe as explained earlier.




I will do the tests you said once I have time, thank you, i appreciate your help.

[nomoresonys]

Simple n-channel mosfet testing: https://www.youtube.com/watch?v=IF740E5bm84

[Nicktronic]

Simple n-channel mosfet testing: https://www.youtube.com/watch?v=IF740E5bm84

Yeah, that's exact same procedure as my steps listed above. On both MOSFETs, after I turn on the MOSFET by putting positive lead to the gate and go back to the drain I get OLwhen I should get continuity. They are both faulty.

[Davi.p]

when you touch red on S and blk on D do you get a 0,5? when doing your test are you touching well the pins? Opfen there is insulating oxide coating on used components and must put little pressure, the best is not to touch tinned ends..

[nomoresonys]

Can you show a picture of Q6850 on the board?

[nomoresonys]

A little more on solder joints: https://www.youtube.com/watch?v=UPf6p7A-ctU

[Nicktronic]

Can you show a picture of Q6850 on the board?

No, it's removed.

[Nicktronic]

when you touch red on S and blk on D do you get a 0,5? when doing your test are you touching well the pins? Opfen there is insulating oxide coating on used components and must put little pressure, the best is not to touch tinned ends..

0.3VDC on one MOSFET and 0.5VDC on the other MOSFET.

[Davi.p]

My soft suspect those are both good, waiting answer to all questions, but all the rest of my list are been tested good?

[Diah]

i did wrote before and again will wrote this last time... edge LED BL if they are cocktails will never working... this why i asked to do the BL-on Jumper early