Can you help me identify the burnt components in my Plasma TV?

[tomgibson]

This image is from the power supply board of my Toshiba 42hp95 that stopped working a few days ago. These are the only damaged looking components that I noticed, but I can't tell what resistance they should have. Any and all help is greatly appreciated.

Tom

 

[TBennettcc]

Can you see the colors clearly on R402? If so, you might try here:

http://www.dannyg.com/examples/res2/resistor.htm

From here, it looks like they might be Orange, Red, Yellow, but I can't be sure. Just plug the colors in to the calculator and you should be good to go.

As far as R401, you might be hosed. It looks like the coating is burned off, along with some of the printing. Have you tried to measure the resistance?

It might help to figure out if you could draw up a schematic? If you can't do that, maybe some VERY CLEAN AND CLEAR pictures of the from and back of the board? We might be able to build a schematic from that.

 

[(*steve*)]

I typed a huge answer to this. It boils down to me thinking that the resistor is likely 0.2 ohms, 1/2 to 1 watt (that's the grey one)

I googled and there is a place that offers access to service manuals and circuit diagrams for this laptop at a price, so maybe that would give you a definitive answer.

Check for components connected to these resistors that have failed short circuit. It is likely to be something attached to a heatsink.

 

[Resqueline]

R401 is marked 0xX2 ohms, and that can (usually) only mean 0.22 ohms.
R402 probably just received a layer of soot from the blast from R401, and is most likely ok.
But R401 is not the only thing "blasted". The dusty 5-pin power IC on the heatsink next to it is probably what failed first.
Using Google I seemed to find a circuit diagram, service manual, & supplement on this site (that appears to be a free service).

 

[(*steve*)]

(Ah, here's my initial reply in another window hiding from me)

Well, firstly, the resistor is unlikely to be the only thing that's failed. You need to determine why that resistor failed so that when you replace it it doesn't simply fail again.

As for its value, it's 0.?2 ohms. The ? might be nothing, an 8, or a 2. I would doubt it is 0.02 ohms. The other 2 guesses are based on the resistor having an E12 value.

I also note that there is no sign of another digit between the 0 and the 2. It looks to me that if there were a 2 or an 8 there, you'd see the top of the digit.

My best guess is that a 0.22 ohm resistor would be a suitable replacement. My guess is that it's between 1/2 and 1 watt.

I also note that it appears it is not intended to get hot in operation as it appears to have been mounted hard on the board and there is no sign of localised long term heating (although that may not be easily visible on a fibreglass board).

I would look at what power components are connected to this resistor and see if any of them measure short circuit.

 

[(*steve*)]

(that appears to be a free service).

That's what I saw too. First you register, then you pay to get access. (They talk about 24 hour memberships...)

 

[Resqueline]

That's what I saw too. First you register, then you pay to get access. (They talk about 24 hour memberships...)

Haha, if it seems to be too good to be true then it most likely is... They want you to get so close you can smell the goodies, and only then do they present the price tag..

 

[tomgibson]

Sorry it took so long, but here's a better pic of that resistor. It IS 0.22ohm, but I'm not sure what the 55k means, or what the characters in front of it are.

This is for a plasma television, in case you were wondering. A google search of "23122503" allowed me to find replacement power supply boards for sale, but I couldn't find detailed information on the circuit.

 

[Resqueline]

Seven months just for the resistor, this might take some time.
I'm not sure about those letters & numbers either, but I am sure they're not important.
It's probably just about the make, model, power, & tolerance. Just get any 0.22Ω resistor of at least the same size (1-2W).
But as I said earlier that's not all you'll have to replace. Looking at the web pic's there's another resistor & transistor that may be bad too.