Does anyone recognize this part? (Solved)

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MisterBill2

Joined Jan 23, 2018
11,580
It looks like a silicon diode, in that seup it would be used to sense temperature. Forward biased at some constant current the voltage varies with temperature.
What sort of damage do you think happened??
 

MisterBill2

Joined Jan 23, 2018
11,580
The simple test will be to measure the resistance with an ohm meter. I have used diodes that have an identical appearance, which is why I suggested a diode. AND the diode forward voltage drop varies in a linear manner as the temperature changes.
Certainly the appearance is also like those thermistor, so it could also be a thermistor.. A resistance check will tell . A diode will have two very different values. And of course a diode should have a band marking polarity.
The part in the picture shows no physical damage, so I wonder what sort of damage the part may have suffered.
 

ericgibbs

Joined Jan 29, 2010
15,342
hi,
That is NOT a diode, how can you possible not see it is identical to the inset image of an NTC thermistor.?
The banded orange rings are the same width, diodes usually a single band at the Cathode end of the diode.

Why do you insist it is a diode.?
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EG 1253.png
 

Thread Starter

kenzo42

Joined Feb 26, 2014
36
I accidental touched it against the circuit board. The wire wound fusible resistor instantly turned black and started smoking. I'll see if I damaged the red part after replacing the resistor today.

Thanks for all responses.
 

MisterBill2

Joined Jan 23, 2018
11,580
OK, and as pointed out by others, this part may well be a thermistor. It seems that it looks also like either one. Now that I have seen the catalog pictures, it certainly could be a thermistor. Given the large spread of thermistor values that probably all look the same, I hope it is not damaged.
 

ThePanMan

Joined Mar 13, 2020
349
member level is now "expert" while yours is only "moderator".
If I answer enough questions - good answers or bad - I'll be an expert too. So "Expert" here means nothing more than they're an expert at giving answers or opinions. Doesn't mean they're "Right" or "Good" answers or opinions, they're just answers or opinions. And opinions are like a**holes. Everybody has one. Some stink. And no - I'm not referring to any particular person or persons here. Just making a general statement.

As for the device shown, I believe it's a thermistor. But that's just MY opinion.
 

shortbus

Joined Sep 30, 2009
9,322
If I answer enough questions - good answers or bad - I'll be an expert too
That "expert" is a milestone he has been shooting for since joining. And many of his answers have fallen into the latter category to get to the milestone. I have the same level but don't consider myself one. But it means the world to him.
 

MisterBill2

Joined Jan 23, 2018
11,580
OK, I guess that others have never seen a diode that looked like that, and never seen a diode used as a temperature sensor.
The simple ohm meter test suggested would have verified it one way or the other.
And what are all the comments about "Expert"??
I never claimed to be an expert. And did not say"IT MUST BE" , only that it also "looks like.", and that it "might also be".
The fact is that it has not yet been verified one way or the other.
My guess now is that it has not been damaged because a package that small can not handle a lot of heat without mechanically failing.
 

Externet

Joined Nov 29, 2005
1,817
accidental touched it against the circuit board. The wire wound fusible resistor instantly turned black and started smoking. I'll see if I damaged the red part after replacing the resistor today.
Murphy's law clearly states that in that accidental contact, the part that failed and smoked the fuse will be the most hard to find and expensive to replace. On that basis, actually the diac or diode or thermo sensor pictured has a good chance to have survived in trade of greater suffering to repair. :rolleyes:
 

MisterBill2

Joined Jan 23, 2018
11,580
If that wirewound resistor did not fail open or shorted then it may still be usable although ugly. An ohm meter check, with all power disconnected, will tell. It will be interesting to know.
This thread also serves to remind us all that it is much wiser to remove power before taking things apart. That applies to veteran workers and Newbies alike.
 

ericgibbs

Joined Jan 29, 2010
15,342
hi Max,
I did read up on that Presto Dehydrator, the thermistor is mounted in the air stream of the fan, in order to monitor the air flow temperature, some notes stated a value of ~10k.

I don't see any purpose of placing a Diac in the air stream of a fan.

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20211120_071854.jpg
 

MisterBill2

Joined Jan 23, 2018
11,580
Certainly now we see a great deal more information than we saw previously. And also we are all able to verify that looks alone seldom are enough to accurately define an item. In addition, it is once again clear that not all guesses are right, which is why we call them guesses.
 

MaxHeadRoom

Joined Jul 18, 2013
24,986
The simple test will be to measure the resistance with an ohm meter. I have used diodes that have an identical appearance, which is why I suggested a diode. AND the diode forward voltage drop varies in a linear manner as the temperature changes.
. A resistance check will tell . A diode will have two very different values. And of course a diode should have a band marking polarity.
It is useless to test a diode with an Ohm meter, the range does not offer sufficient current to FWD bias it.
This is why there is a diode test range that actually imposes a voltage in order to Fwd bias it and measures the volt drop across the diode.
 
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