Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

[paulxxxx]

When I turned it on, it has the internal generated sound, but no audio signal from the TV programming.

The logic board in the center of the TV blinks at about 1 Hz.

I checked the voltages to each boards and they seem to be OK

Visually, there are no bulging capacitors, no burnt transistors, at least when viewed from the top side of the boards.

The X board buzzes.

There is no picture at all.

I play with electronics from time to time but I don't know anything about TV. Does the audio signal go through the X-Y boards as well?

Thanks!

[dskall]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Disconnect main to control board and connect jumper to autogen on control board. See if you get a test pattern.

[paulxxxx]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Disconnect main to control board and connect jumper to autogen on control board. See if you get a test pattern.

Help me out here, what is a "main" (and X-main, y-main)?

Is there any markings for "autogen" on the control board?

[dskall]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Help me out with some good pictures and good close up of small control board.

[paulxxxx]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Here we go.

[lotas]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Here we go.

Disconnect the main cable from the logic,
put a jumper on the Logic 3-4 next to the fuse and turn it on from the remote control.

[paulxxxx]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Thanks.

But it did seem to do anything.

I don't have a remote, I just turned it on using the button in front.

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

I would suspect lots of things, first I would remove x board and test the transistors, the ones on the heatsink seem to go bad a lot but check them all, good policy to check everything on heatsinks and the the usual resistors and diodes, plasmas are notorious for one bad board taking out another, you want to make sure your buffer boards have no shorts or problems, theres some good videos on youtube for checking them, tampatec and norcal715 have covered the procedure.

[paulxxxx]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

I would suspect lots of things, first I would remove x board and test the transistors, the ones on the heatsink seem to go bad a lot but check them all, good policy to check everything on heatsinks and the the usual resistors and diodes, plasmas are notorious for one bad board taking out another, you want to make sure your buffer boards have no shorts or problems, theres some good videos on youtube for checking them, tampatec and norcal715 have covered the procedure.

The x-board is buzzing. Is it a good sign or a bad sign?

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

its all about the testing, I dont usually mess around with plasmas, too bulky and heavy, see if this helps, a pro there, notice the heartbeat about 2 times per second on a healthy tv, try the tests: https://www.youtube.com/watch?v=-7zWKY2Hwnc

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

heres Bobby doing your model, its what I suspect is wrong with yours, test those mosfets/transistors, last one I messed with had all bad mosfets on x-board on heatsinks and a bad diode, then I found the y-buffers to be shorted and called it off, was too much trouble for not much reward, it only does 720p: https://www.youtube.com/watch?v=fqs1Ig2UM0M

[paulxxxx]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

heres Bobby doing your model, its what I suspect is wrong with yours, test those mosfets/transistors, last one I messed with had all bad mosfets on x-board on heatsinks and a bad diode, then I found the y-buffers to be shorted and called it off, was too much trouble for not much reward, it only does 720p: https://www.youtube.com/watch?v=fqs1Ig2UM0M

Thanks. I suppose I will have to pull these transistors and test them one by one.

Somehow, I find my soldering iron isn't powerful enough, especially for melting the solder pins on the heat sink. Do they use a higher temperature solder here?

What would be a good soldering iron for general electronics repair that doesn't damage the PCB?

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

testing igbt transistor for shorts in circuit, plenty more videos on youtube if you want to go thru them: https://www.youtube.com/watch?v=T1y3gYL-KmY

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

testing y-buffer board for shorts: https://www.youtube.com/watch?v=3Oq2MsU0XOQ

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

here's ABOVE "average joe" testing for shorts: https://www.youtube.com/watch?v=aZF57Bok7Ws

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

for soldering like this its nice to have a good adjustable iron but they cost more of course, if you dont intend on doing much soldering you can get by with a 40 to 60 watt iron from one of the big box stores or wherever, I wouldnt go lower than 40 watts tho.

[diif]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

Thanks. I suppose I will have to pull these transistors and test them one by one.

Somehow, I find my soldering iron isn't powerful enough, especially for melting the solder pins on the heat sink. Do they use a higher temperature solder here?

What would be a good soldering iron for general electronics repair that doesn't damage the PCB?

The heatsink is absorbing the heat, you need a decent iron to remove them.
What's your budget ?

[nomoresonys]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

This is your best bet if it is a match, read the fine red print there about matching, 33 bucks is nothing compared to the trouble of replacing components, imo, be sure and test those transistors and other components with your multimeter and test the y and y-buffer boards, look at those videos I linked: https://www.ebay.com/itm/36216634083...Bk9SR76p74_8YA

[paulxxxx]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

The heatsink is absorbing the heat, you need a decent iron to remove them.
What's your budget ?

As cheap as possible. LOL.

I have a few already, one for for modern low power electronics with thin tip, one with large tip for older PCBs that are easily damaged by high heat. This one, the biggest, is a 30W cheapo from sometime ago. It seems to have a gap between the heater and the tip rod that gets bigger as oxidation increases with time. If there is a way to get better heat conduction, I bet this might be good enough.

[dskall]

Re: Samsung Plasma TV PN50B450B1D No Pic, No TV Sound

You shouldn't have to remove anything till you find a problem.