Toshiba 42H82 Fusible Resistor Wattage Revision

[Krankshaft]

Recently the convergence went out on my Toshiba 42H82.

Upon opening the set up one of the fusible resistors was cracked and open circuit.

Time for another STK replacement.

I have 2 of these sets in my house and have already went through this process on the other same model set.

FYI I upgraded the STK-392-110s on the other set with the newer STK394-160 from the advice given on these forums and I am hoping that they will be more reliable.

I will be doing the same upgrade on this set.

The service manual says that this resistor is a 1.8 ohm 1 watt on my other TV this is true.

But on this set it seems like the signal board went through a revision the fusible resistors on this board look like they are 1.8 ohms at 2 watts.

I don't have much experience on resistor sizes over 1 watt so I've attched a pic.

Is it 2 watts?

I included a pic with and without a ruler since its a bit hard to judge size from the pics.

I'm just going to order this flameproof metal film resistor through my electronics distributor so that I don't have to wait for a special order through Toshiba.

Thanks For The Help In Advance

[lcaillo]

It is not possible to do more than guess from a visual insection. Regardless, I would use 2 watt resistors. The power rating is simply the maximum that they can dissipate before burning up and has no effect on the performance. As long as the resistance is correct and the power rating is at least what is needed, larger is not a problem. These are not designed to fuse to protect the output ICs. On the contrary, over rating them in power is safer, because an open resistor is more likely to cause output or damage to the yoke or even a CRT. In circuits where the resistors are designed to act like fuses for protection if too much current flows, you would not want to over rate for power. This is not one of those cases. i.e. when in doub use the larger power rating on convergence OUTPUTS. Just make sure that they are flameproof, metal film, or wirewound resistors and not carbon resistors.

[Krankshaft]

Thanks for the help I placed an order for 2 watt metal films from my supplier they are made by Vishay and datasheet says that they're flameproof.

The resistor got so hot when it went open it turned a brown band to black and a gold band to brown. I thought it was another value at first since the band's colors looked so convincing.

Luckily the resistors around it were all the same value 1.8 ohms and the parts section of the service manual set me straight to what its value was thanks to it's component number on the board.

[Krankshaft]

Thanks for the recommendation to use the STK-394-160s they worked great.

I used Arctic Silver 5 (CPU grade silver bearing thermal compound) rather then the cheap white stuff.

The convergence was almost perfect without touching anything on initial power up but it still was a bit off.

When I went into service mode rather then just touch it up I decided to give it a REAL convergence with my overlay.

After an hour and a half of staring at the crosshatch while lining up the green to the grid slowly losing my mind in the process I was done. Now when I look at vertical scrolling text it doesn't bow an and out .

The new resistors were about 50% smaller then the originals so I replaced all 6 of them so that they are all the same size.

No real reason for it I just didn't want to send the new ICs to their grave for being lazy.