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Anyone know what this is?

ARMANDO

Aug 5, 2016
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My guess is a very small diode? and the red dot indicates positive side or polarity.20170709_135437.jpg
 

kellys_eye

Jun 25, 2010
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A diode seems the most reasonable conclusion but a simple test will reveal the truth.
 

ARMANDO

Aug 5, 2016
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How to test?
I set my Fluke Multi meter to diode/continuity setting and with the red tip on the side that has a red dot with the black on the other side I get nothing. flip the leads around and I get a short beep and a reading of 1.808 ,
1.808 what? i don't know what this value means.
Is it a diode?
 

kellys_eye

Jun 25, 2010
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Your Fluke may have a diode test range as you state. It will show the forward volt drop across a diode - which can be anything from 0.2V to 0.8V in the forward direction, zero in the reverse for 'standard' diodes..

If your meter is being used correctly it is showing a forward volt drop of 1.8V - pretty high for a 'normal' diode but possible with a high voltage device (which that might be). What is the voltage rating of the capacitor adjacent to it?
 

ARMANDO

Aug 5, 2016
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600VDC

I think this is a high voltage device. its from a scanning electron microscope that need up to 30KV.
 

kellys_eye

Jun 25, 2010
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Yup - the 1.8V reading may be correct then. Still a diode.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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The mark on the diode typically indicates the cathode. That is NOT the +ve end, but if you have just a simple understanding of power supplies it is where "the positive comes out".
 

dorke

Jun 20, 2015
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Armando,
Please take care,this equipment can kill you!
I hope you know what you are doing!
 

73's de Edd

Aug 21, 2015
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The casing and hand applied, off color dots, reminds me exactly of units that were made by Varo, for use in their Starlight Nitescopes at that manufacturing timeframe.
They used multiple series diode junctions internally and were very generous with underrating their breakdown specifications.
 
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