Do resistors fail like dominoes?

starLED said:

I was watching an electronics repair channel on YouTube named Nick's Electronic Repair and the guy is fixing a lot of different boards by replacing a bunch of resistors.
For example, in this video he replaced about 30 resistors or so, and I am not sure that was the issue here.
How often do resistors fail like dominoes?

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They don't, and it would be EXTREMELY rare to fix things by replacing multiple resistors, presumably it's yet another piece of useless crap on YouTube?.

Nigel Goodwin said:

They don't, and it would be EXTREMELY rare to fix things by replacing multiple resistors, presumably it's yet another piece of useless crap on YouTube?.

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Well, this guy claims he has repaired 27,000 devices since he's working on repairs.
He has two channels, one for TV repairs and other various devices.
I noticed that TV repairs are often done by replacing bunch of transistors, and other devices bunch of resistors.
I doubt he knows what the exact issue is.
Funny thing, replacing bunch of resistors works.

Nigel Goodwin said:

They don't, and it would be EXTREMELY rare to fix things by replacing multiple resistors,

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I agree with that.

However, in the video the guy did measure many resistors which appeared to be high in value.
It would be interesting to know what made them high resistance...
Possibly it is that they are the cheapest crappiest resistors available.

I would expect many resistors to "go high" in an ancient piece of equipment form the 1960s or 1970s, where all the resistors are horrible carbon composition types, but not something made in the last couple of decades.

starLED said:

Even though he measured higher resistance than expected, still resistors can measure in circuit way more than the spec. He doesn't measure them off-circuit.

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I would expect a resistor which is in circuit to either read its correct value, or something lower depending on the circuit configuration.

If a resistor reads higher than its normal value it is certainly faulty.

When a resistor in in circuit, it can be in parallel with various other circuit elements.
Connecting a resistor in parallel with another resistor will ALWAYS give a lower combined resistance, NEVER a higher resistance.

So when the guy in the video measured a higher resistance, he could be sure that the resistor he was testing was faulty, there was no need to measure again when the resistor had been removed from the board.

Looking at his soldering technique, he seems to be a believer in the mantra

"The bigger the blob, the better the Job" !!

JimB

An afterthought...
The faulty resistors were not just high in value, but probably open circuit.
Could it he that the mass failure of resistors is due to the metalised ends becoming detached from the resistor bodies due to heat cycling, or physical bending of the circuit board?

JimB said:

Could it he that the mass failure of resistors is due to the metalised ends becoming detached from the resistor bodies due to heat cycling, or physical bending of the circuit board?

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This specific board is from the Bobcat excavator which is heavy machinery working in tough conditions, and Nick said that most often failure are the resistors, due to heat.
There were also a lot of cracked joints.