Happened again. Resistor go short!

[CapLeaker]

That's now the second time in my repair career that a through hole resistor go short!
it was a Vishay CPF124K900FHB14 1W resistor measuring new 24.9kohm. <- notice the KILO ohm. Well now it measures 28.1 Ohm! See picture and PDF attached. This is something very rare happening, but apparently it does happen!

[stj]

carbon type?
i'v seen carbon resistors go down in value when run at their voltage limit.
i only buy metal film because of that.

[CapLeaker]

carbon type?
i'v seen carbon resistors go down in value when run at their voltage limit.
i only buy metal film because of that.

Read the PDF. It’s a METAL FILM, flame proof resistor!

[stj]

strange.
unless there is rust under the paint, but that usually only effects wirewound parts.

[CapLeaker]

strange.
unless there is rust under the paint, but that usually only effects wirewound parts.

Strange all right! This should not be happening, but yet it does! What’s making it worse is look at the prices of these… you’d think you should get quality.

[redwire]

I have only seen TO-220 style power resistors drop in value if they get overloaded. Bourns PWR220T 20W thick film resistors, which is scary. They are only rated for 200% surge. I tried to take one apart and there seems to be a short between the loops that happens when the metallization spatters inside.

[CapLeaker]

I have only seen TO-220 style power resistors drop in value if they get overloaded. Bourns PWR220T 20W thick film resistors, which is scary. They are only rated for 200% surge. I tried to take one apart and there seems to be a short between the loops that happens when the metallization spatters inside.

Nice. TBH I haven’t seen your fault with these big power resistors. But even then these power resistors don’t have a high ohms rating like 24.9kOhm. Interesting case though and it’s not a cheap resistor either. Given, it is a rare thing to happen, but it did happen twice for me now that are extreme.

[redwire]

Your resistor fail is really wierd - something inside must have carbonized? Either the core (ceramic) or an arc inside that made it across all turns of the element. Or you multimeter is baked.
I would crack that resistor apart, for the science lol. I'd bet a good blast of say 24V would "fix" it" if the internal short is a bit weak.

[CapLeaker]

Your resistor fail is really wierd - something inside must have carbonized? Either the core (ceramic) or an arc inside that made it across all turns of the element. Or you multimeter is baked.
I would crack that resistor apart, for the science lol. I'd bet a good blast of say 24V would "fix" it" if the internal short is a bit weak.

Nah, my Fluke DMM’s are O.k.
crack that resistor apart? Hmm… I have to find it in my electronic trash bin. Maybe something for a rainy day.