Sony KDL-37XBR6 Black Screen :(

[budm]

Re: Sony KDL-37XBR6 Black Screen

No heatsink on that switched MOSFET, it is probably 8-pin SMD device.

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

OK, thanks. So what appears to look like a heat sink on the main board may be something else? I'm not sure, just wondering.

Perhaps I could get a better close up photo of the main board just in case you may need to look at something else.

[budm]

Re: Sony KDL-37XBR6 Black Screen

You have to look at the schematic diagram of the main board to locate that MOSFET first.

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

You have to look at the schematic diagram of the main board to locate that MOSFET first.

OK, I've looked at both pdf files on the schematics and I can't seem to find the MOSFET. Would you happen to know where it is located or a number?

Thanks!!!

[budm]

Re: Sony KDL-37XBR6 Black Screen

OK, I've looked at both pdf files on the schematics and I can't seem to find the MOSFET. Would you happen to know where it is located or a number?

Thanks!!!

Don't you see the part designators as shown in the diagram?
There is fuse F1422, MOSFET Q1423 in the diagram that I even put red circle on them, I spend lots of time looking through many pages to locate those two pages for you, all you have to do is to look at both side of the board to locate those two parts to check them. I do not have the board in front of me to look at, it is up to you to spend time locating them.
May be you should just buy new main board to try out.

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

Don't you see the part designators as shown in the diagram?
There is fuse F1422, MOSFET Q1423 in the diagram that I even put red circle on them, I spend lots of time looking through many pages to locate those two pages for you, all you have to do is to look at both side of the board to locate those two parts to check them. I do not have the board in front of me to look at, it is up to you to spend time locating them.
May be you should just buy new main board to try out.

OK, now I see what you are saying. Sorry, I overlooked them! I'll have to take the main board screws off and see if I get any voltage on those components!

I do appreciate you posting the pdf files and personally thank you for that!

I'll post back when I get a chance to check the voltages out! Thanks again, and have a nice day!

[budm]

Re: Sony KDL-37XBR6 Black Screen

Check the fuse first, it will be really small fuse.

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

Hi budm,

I've been really busy the last few days. I will try and get to checking the fuse and MOSFET shortly. I apologize for the delay. I will post back when I have checked the fuse and also see if there is any voltage on that transistor. Thanks again!

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

Hi budm,

Sorry it took me so long to reply back. It's been a brutal week!

Anyhow, I tried to trace the MOSFET and fuse from the schematics you had posted, but I am having difficulties finding them on the board. I took a couple of photos of the front and back side of the board. Perhaps you can locate these 2 components with a red circle?

Once I know where they are located, I can check them. Thanks again for your help! Much appreciated!!!

[budm]

Re: Sony KDL-37XBR6 Black Screen

This is really bad, they did not print any designators on the board. Need to find the board lay out to get the part location.

[budm]

Re: Sony KDL-37XBR6 Black Screen

See post 37 and look at he service manual for the board layout with parts designators.
Pages from 56-100 sony_kdl-32xbr6_kdl-37xbr6_chassis_ex1-2.pdf

[budwich]

Re: Sony KDL-37XBR6 Black Screen

you are certainly making a lot of work for budm. why don't you do as suggested earlier.... follow the 12v line coming from the power board to the main board and then use a meter to follow the track to the components somewhere on the main board should go towards the fet / fuse.

[neilc6]

Re: Sony KDL-37XBR6 Black Screen

I replaced a fuse on 40Z4100 with similar boards so can give you some help. On your second pic, back of the board at the top edge (back side of LVDS connector) is a 8 pin SOIC which should be Q1423. The silkscreen marks F1422 5A 24V at the same location and this fuse should be checked. There should be a signal from the processor which switches 12V to the tcon. Check the fuse and the FET.

https://www.badcaps.net/forum/showthread.php?t=66995

[budm]

Re: Sony KDL-37XBR6 Black Screen

You sure made me do lots of work for you. See picture.

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

I replaced a fuse on 40Z4100 with similar boards so can give you some help. On your second pic, back of the board at the top edge (back side of LVDS connector) is a 8 pin SOIC which should be Q1423. The silkscreen marks F1422 5A 24V at the same location and this fuse should be checked. There should be a signal from the processor which switches 12V to the tcon. Check the fuse and the FET.

https://www.badcaps.net/forum/showthread.php?t=66995

Thanks for your help! Much appreciated! I will locate the fuse and the FET and see what's what. I'll post back here with that info!

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

You sure made me do lots of work for you. See picture.

Sorry to make you extra work! I didn't realize it was difficult! My apologies!
I'll check to see if that fuse is good, and also use a pin to touch the contacts on that FET. I will use the ground side of DMM to the metal chassis as I did before to get the measurements. I'll report back here when I'm done. I should be able to do this in a little while! Thanks again and sorry to have put you through any trouble!

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

OK, I checked the fuse (F1422) and no continuity! I'm figuring that if the fuse is bad, then I won't be able to get any voltage readings from the MOSFET?

I can still try and see if I can get any voltage on the FET, but if the fuse is bad, should I still continue to try?

Also, I will have the BU board unscrewed and away from where it mounts. Can I still get voltage, as it may not be grounded properly?

Thanks again!

[budm]

Re: Sony KDL-37XBR6 Black Screen

I want you to think about this logically, so fuse is blown so what Voltage should you see at least at one end of the fuse?
If you are not sure about the Gnd ref. then use the GND on the main board or GND pin of the connector for GND ref.

[Gammaray]

Re: Sony KDL-37XBR6 Black Screen

I want you to think about this logically, so fuse is blown so what Voltage should you see at least at one end of the fuse?
If you are not sure about the Gnd ref. then use the GND on the main board or GND pin of the connector for GND ref.

I was thinking around 12V. I did measure one side of the fuse and it was 12.06V and then went to 12.26V when the power button was pressed to on. The other side of the fuse shows no voltage. So if I change this fuse out with same, will this fix the problem? Thanks!

[vinceroger69]

Re: Sony KDL-37XBR6 Black Screen

have you tested ohm reading on each side of the blown fuse to see if there is a short on on side? put meter in ohms mode one probe on ground and then test both sides of the fuse what readings do you get.