Anyone ever had a resistor suddenly "go bad"?

Started by slacker, November 08, 2007, 05:06:52 PM

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slacker

My ADA flanger clone was working fine then I came to play with it tonight and there was no flanging. I poked about with my DMM and the supply voltage to the SAD1024 was reading about 0.5volts, the rest of the circuit was still getting 15.
I figured the SAD might of fried somehow so I pulled it out and measured the voltages again and the supply pin was still only at 0.5 volts.
My next thought was that there was a short to ground somewhere so I had a good scrape around in case there was a solder bridge, still no improvement. There's a couple of electro caps between the supply pin and ground so I though one of them had gone bad so I removed them both, still nothing.
I was getting a bit confused now so I removed the resistors attached to the SAD and measured them. Turns out the 10ohm resistor between 15volts and the SAD's supply pin had broke somehow, it now measures about 1.3Meg  ???

Anyone else ever encountered this?


puretube

#1
though I`m not a big friend of measuring components "in situ":
did you measure the R at the physical components body`s leads,
or at the pads on the "copper-side" ?

(and did you do a 2nd measurement with reverse polarized probes?)

[EDIT:] yes, leads can (temporarily) break off components bodies,
and can (temporarily) reconnect magically...  :icon_eek:
(especially, when bent sharply,
or when used/re-bent several times).

slacker

#2
I removed the resistor from the board and measured it. The leads still seem to be firmly attached to it and bending them into different positions doesn't affect the reading at all so I can only assume it's damaged internally somehow.
It's weird how it worked perfectly for a couple of weeks then suddenly went bad, if it had been an intermittent fault I could have understood it more.

puretube

so it does seem to happen:

replace it, and observe the new one`s behaviour