Take this for what it's worth or not worth. Resistors just don't fail and when we see a cooked resistor what we see is generally just a symptom and not a cause. The question then begs why did a resistor have excessive current causing it to fail? Then we can add if I replace a 1/2 Watt resistor with a 3 Watt what will happen to whatever caused the initial failure? There is a very good possibility that you replace the cooked resistors and promptly have more cooked resistors.

Ron

No the resistors are ok at the moment, I am changing all the speed control components on the board , 2x Capacitors , 1x Triac, 2x Resistors , they are quite old , I don't want to spend time and money replacing the other items and leave the old resistors in place .
PS: The pics shown , are one of the legs of the Resistor and one leg of the Capacitor de-oldered by me , they are not burnt in any way .

Spike

 

Given those dimensions, I would have to think that they are 1/2 W.

http://www.resistorguide.com/resistor-sizes-and-packages/

Did you measure the diameter across the middle or the end?

The end

 

Edit #1: Just saw response #21
Still no response about what's wrong with the resistor.

The wire to the 56R resistor looks vaporized but no damage to the resistor. Copper boils at 2565°C (4643°F). That looks more like electric arc damage. If so, any 1.8 V IC may also be damaged.

Edit #2: Preventive maintenance on PCB's because they are "old" is a myth. Resistors don't go bad. Moreover, the TS is probably more likely to introduce damage rather than prevent further "degradation" over the next 50 years or so.

 

No the resistors are ok at the moment, I am changing all the speed control components on the board , 2x Capacitors , 1x Triac, 2x Resistors , they are quite old , I don't want to spend time and money replacing the other items and leave the old resistors in place .
PS: The pics shown , are one of the legs of the Resistor and one leg of the Capacitor de-oldered by me , they are not burnt in any way .

Spike

 

The end

Ironic! Twenty-two posts to reach that conclusion?

 

Ironic! Twenty-two posts to reach that conclusion?

My original question was , " Could I fit a 3W Resistor in place of a 1/2W Resistor !

 

My original question was , " Could I fit a 3W Resistor in place of a 1/2W Resistor !

And the conclusion was !

 

Ironic! Twenty-two posts to reach that conclusion?

What conclusion? That he measured the diameter of the resistors at the end instead of the middle?

 

No the resistors are ok at the moment, I am changing all the speed control components on the board , 2x Capacitors , 1x Triac, 2x Resistors , they are quite old , I don't want to spend time and money replacing the other items and leave the old resistors in place .
PS: The pics shown , are one of the legs of the Resistor and one leg of the Capacitor de-oldered by me , they are not burnt in any way .

Spike

Then yes and have at it for your application.

Ron

 

By the way, the middle measures 2.14mm .

 

Edit #1: Just saw response #21
Still no response about what's wrong with the resistor.

The wire to the 56R resistor looks vaporized but no damage to the resistor. Copper boils at 2565°C (4643°F). That looks more like electric arc damage. If so, any 1.8 V IC may also be damaged.

Edit #2: Preventive maintenance on PCB's because they are "old" is a myth. Resistors don't go bad. Moreover, the TS is probably more likely to introduce damage rather than prevent further "degradation" over the next 50 years or so.

The machine does not work , just replacing them to see if it will , I thought best to change them all in one go !

 

The machine does not work , just replacing them to see if it will , I thought best to change them all in one go !

That is not very logical.

 

That is not very logical.

Why not , it is only costing me £5 for them all ! , 10 min max to solder them back on ! .

 

Then why did you post your query here. Just do it, and see if the problem is fixed.

 

Then why did you post your query here. Just do it, and see if the problem is fixed.

Because I was wanting a answer to my my original question , which I am still unsure if I have had it , that is all I wanted from you good people , if you want to go on talking about it , and not giving me the answer to my question we will end up with 34 replies !

 

You have been told by several people that it almost certainly is just fine. You cannot expect an absolute guarantee of that based on the information you have provided because we don't even know what that resistor is used for in the circuit.

What if that circuit uses the temperature from the resistor to trip some part of the circuit? Replacing the resistor with a higher rated one will result in the surface temperature of the resistor being lower and that could affect how the circuit operates. Is that likely? No, not likely at all. But is it possible? Yes.

 

You have been told by several people that it almost certainly is just fine. You cannot expect an absolute guarantee of that based on the information you have provided because we don't even know what that resistor is used for in the circuit.

What if that circuit uses the temperature from the resistor to trip some part of the circuit? Replacing the resistor with a higher rated one will result in the surface temperature of the resistor being lower and that could affect how the circuit operates. Is that likely? No, not likely at all. But is it possible? Yes.

Yes you are absolutely correct , I tried to find a drawing for it , but no luck, will just have to take the chance , thanks anyway for all the replies, it was a interesting discussion for me , as again from this site have learned something .
Spike

 

I know we are up to post #37 , but does this make sense for the 56Ω Resistor :

It is important that the 56 ohm resistor has good pulse rating. Metal film resistors will fail in this location. It is a snubber resistor and is subjected to high pulse current. Even if power rating is ok.

.

Spike

 

I know we are up to post #37 , but does this make sense for the 56Ω Resistor :

It is important that the 56 ohm resistor has good pulse rating. Metal film resistors will fail in this location. It is a snubber resistor and is subjected to high pulse current. Even if power rating is ok.

Film resistors are the worst choice for this capability. Carbon composition is the best in this case.