Samsung 50 Plasma donated to me.

[Ghssoccer1]

Alright, So I have read and read and read on the site about all kinds of things. However. I was given a Samsung 50" Plasma tv with which to get my feet wet. The tv was taken to a shop which said it needed a new MAIN CBA. Do to a power surge that fried it. Now This being my very first attempt at fixing a tv what better way than to just replace a board right?!?! Problem is I am not sure which the "MAIN CBA" board is.

Model-PN50B450B1DXZA
Version- SL04

Please help a noob. I'm greatful for anything you guys can help me with.

[tom66]

Re: Samsung 50 Plasma donated to me.

I don't know what a main CBA is. It sounds like a made-up term a less than honest TV technician may use.

Closest I can think of is "Control Board Assembly", as some plasma TVs have a control board.

The B450 series is very prone to the failure of the Z-sustain / X-main board which is very cheap.

You will first need to plug in TV and document the symptoms.

Then, take the cover off, and take good, clear, focused pictures of the insides of the TV.

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

I was told it was "main CBA" Or Main Circuit board assembly. However, i'll give a quick diagnostic and some pics asap.

[randtek]

Re: Samsung 50 Plasma donated to me.

In Samsung terminology (for this model anyway), there are 4 boards with "Main" in the name - the "X Main", the " Y Main", the "X Main Buffer", and the "Logic Main". "Main Board" really does not give you enough information.

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

ALRIGHTY!!!!! And here we go. So, I plug it in and nothing. I have a red LED light up front. But it does nothing, I can hear a little "hmmm" like its running. However, no response to the power keys on the frame NOR on the remote. Here are some pics of the back. Alright, now lets do this.

[RCFLYER]

Re: Samsung 50 Plasma donated to me.

Do you hear a clicking noise when you plug it in?

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

Yes, Yes I do.

[PlainBill]

Re: Samsung 50 Plasma donated to me.

ALRIGHTY!!!!! And here we go. So, I plug it in and nothing. I have a red LED light up front. But it does nothing, I can hear a little "hmmm" like its running. However, no response to the power keys on the frame NOR on the remote. Here are some pics of the back. Alright, now lets do this.

The power supply is a fairly standard design. Notice the broad whit line zig-zagging from the top to the bottom of the board. There are two transformer straddling that line. The smaller transformer is for the standby supply, the larger is for the main supply. The fact that you have an LED indicates the standby supply is working.

There is a wide ribbon cable coming from the bottom right side of the power supply and going to the main board. Are there legends at either connector indicating the function of the pins? A close-up picture of that corner of the power supply would be appreciated

There have been a number of problems with these, it seems we will be seeing many more of them.

PlainBill

[RCFLYER]

Re: Samsung 50 Plasma donated to me.

Check out my thread I have a similar problem. Make sure you pushing the source button on the remote to find the correct input you are supplying the TV with, such as cable. I was able to hear the TV when I pressed it a few times.

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

Ok, So I'm at a loss for words....I trouble shoot this and it turns on without issue, sounds lights and the whole nine yards...Now what?

[RCFLYER]

Re: Samsung 50 Plasma donated to me.

It"s Working? Let it play to see if any hicups occur. Did pressing the source button do the trick?

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

No, literally, I just plugged it back in and it took off. I'll let it play a dvd and see what happens.

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

I did make sure it was on a surge protector..As this was supposedly what caused it to "quit working"

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

Found the hiccup. So I let it play a dvd for a little over an hour..I shut it off and shut down the surge protector. NOW, when I turn it all back on, No start up clicks. Same as before. dead.

[dumpystig]

Re: Samsung 50 Plasma donated to me.

For starters I would be looking for dry joints on the PSU. Quick, simple and no cost

[PlainBill]

Re: Samsung 50 Plasma donated to me.

For starters I would be looking for dry joints on the PSU. Quick, simple and no cost

Correct, it's almost certainly a bad solder joint, and the power supply is the place to start. But it could also be on the main board. That's why I try to 'divide and conquer' by determining if the 'PSON' signal is active.

PlainBill

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

Ok, So once it cools, it comes back on, such as letting it sit over night. So for the beginner, where should I start, where the plug comes in at the power supply to the "main Board" in the center of the back? And as for solder point what should I be looking for? Or should I simply start hitting the joints with heat and see if that cleans it up?

[tom66]

Re: Samsung 50 Plasma donated to me.

Check the joints around the big power components bolted to the heatsink. Look carefully for any cracks or dull colour.

[Ghssoccer1]

Re: Samsung 50 Plasma donated to me.

So, I hit up a couple of the solder joints just to ensure. From the power lead starting at the corner of the main board where that power lead comes in. Still no luck. Once it heats up and gets shut off or unplugged, it stays off for a bit...I can turn it off and on with the remote while I'm testing it without issue..but once its unplugged, it has to cool.

Just to verify i'm on the right board. Its the biggest board in the center of my pics, correct?

[dumpystig]

Re: Samsung 50 Plasma donated to me.

2nd pic, board @ top left. A 'couple' of joints won't suffice. Re-flow all the larger, heavier joints starting from the brown and blue wires that enter the board @ bottom left, follow the traces from there re-flowing as you go, and make sure you do both sides of the transformers. When re-flowing add a tiny amount of new solder to each joint.