Author Topic: Help identifying a component  (Read 1504 times)

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Offline sensoTopic starter

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Help identifying a component
« on: August 25, 2014, 11:18:38 pm »
Good night, I have been (trying to) repairing a PVL ignition cdi unit with a friend, and there are two strange SMD components that I have never seen, its the two black mini-melf with two stripes each that I don't know what it is.
For now the cdi is working as expected, but I'm curious to what those two devices might be, the only thing that we measured was the cold and hot resistance of them, its about 0.5M ohms at room temperature(around 25ºC), and at around 80ºC they measure 50kOhms for the smaller one and 80kOhms for the bigger one, and that rises very, very fast as they cool down.

Sorry  for the blurry photos, taken in a hurry because we where eager to try it out  ::)



 

Offline algorithm

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Re: Help identifying a component
« Reply #1 on: August 25, 2014, 11:22:40 pm »
My guess is a carbon resistor? Hope that helps.
 

Offline sensoTopic starter

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Re: Help identifying a component
« Reply #2 on: August 25, 2014, 11:34:18 pm »
But having only two colour bands seems very odd, never saw anything like that.
Also forgot to tell, with the continuity they dont beep in any direction, but that might be a by-product of such high resistance.
 

Tac Eht Xilef

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Re: Help identifying a component
« Reply #3 on: August 26, 2014, 12:28:48 am »
Two band MELF would usually be a diode. There is a sort of standard colour code, but there's also a lot of manufacturer-specific ones.

Probably a zener or transorb if they're high resistance bothways and showing that sort of tempco, but the color bands don't match any zeners I'm familiar with.
 

Offline sensoTopic starter

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Re: Help identifying a component
« Reply #4 on: August 26, 2014, 12:32:14 am »
I suspect they are something along those lines, the big one is between the storage cap(charged up to 400v) and ground and the other is between the SCR gate and ground, I suspected zeners or varistors to protect the SCR a bit.
 


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