resistor question bad or good

[insomnia]

i have a resistor in a circuit that looks burnt the paint is coming of it now checking with my ohms meter it gives the correct reading could it still be gone i cant check it when its powered cause i dont have the power supply for it i have one also that brown red brown gold which is 120 ohms +-5% out of circuit it reads 155.5 ohms how important is the tolerance

 

[tvtech]

Prey tell. What kind of circuit is it ??? In a TV, Radio......

As an afterthought, you are probably hunting in the wrong area. Resistor tolerance is not important for well designed consumer electronics.

 

[Nigel Goodwin]

Prey tell. What kind of circuit is it ??? In a TV, Radio......

As an afterthought, you are probably hunting in the wrong area. Resistor tolerance is not important for well designed consumer electronics.

Not always, some parts are more critical than others - but in any case, it's outside it's tolerence so is faulty.

 

[insomnia]

its of a chasie its motherboard a friend gave me and he is really stuck its for powering a bowling machine the result is the machine just keeps cycling wont do anything else it full of nand gates thats more less what the the board is a few diodes also

 

[audioguru]

In my entire electronics career I have never caused a resistor to get too hot.
Maybe it burns shorted or fuses open. Try it to see.

 

[insomnia]

thanks for your reply when you mean burns shorted what do you mean also what is the best way of testing nand gates in circuit is it possible with with a meter

 

[bychon]

Dear audioguru,
I believe the Guinness Book of World Records should be notified.

 

[maor]

Dear audioguru,
I believe the Guinness Book of World Records should be notified.

Thats a record I'm willing to break.

 

[tvtech]

In my entire electronics career I have never caused a resistor to get too hot.
Maybe it burns shorted or fuses open. Try it to see.

I used to see it on a daily basis in the TV game. Telefunken 711 frame stage always ran HOT. Paint on the two "protection" resistors always crumbled in your hand when you touched them.

Yet the resistors themselves were still good to go. And always within reasonable spec.

If you were sitting with a frame fault......changing the two "faulty" looking resistors helped buggerall........the fault was elsewhere.

And then I could go on about resistors in newer sets that are designed to blow if too much current is drawn through them. Flameproof etc.

That's why I love Electronics. Ever changing.

 

[Noggin]

In my entire electronics career I have never caused a resistor to get too hot.
Maybe it burns shorted or fuses open. Try it to see.

I think I've made up for your lack of killing resistors. It wasn't long ago that I was vaporizing 50mOhm metal strip resistors. They made for very frightening failures until I got used to them shorting across 4.8 mF @ 525v.

 

[audioguru]

Those old carbon composition resistors might have melted into a short circuit. I think film resistors burn out open like a fuse.
I guess "flame-proof" resistors have high temperature paint and burn out open before they get too hot.

 

[bychon]

Sir, I doubt your sincerity. It seems like only yesterday that you said you had never caused a resistor to get too hot.**broken link removed**





(Dear Diety, please let this one understand this is supposed to be funny.)

 

[audioguru]

Sir, I doubt your sincerity. It seems like only yesterday that you said you had never caused a resistor to get too hot.**broken link removed**

Correct.
I never caused a resistor to get too hot so I simply guess what happens to them when other people make them too hot.

 

[bychon]

Glad we got that cleared up. **broken link removed**