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Diode testing questions..

Posted on 2/20/14 at 11:32 pm
Posted by Napoleon
Kenna
Member since Dec 2007
69140 posts
Posted on 2/20/14 at 11:32 pm
I had a High Voltage system with a bad diode. it was shorted, and was arcing to ground from the capacitor..
So I bought a couple of new ones. I threw the first new one on and I got no change.

So I tested it and from the Anode to the cathode it reads open and from the Cathode to the Anode it reads open.
I should be getting Closed from Anode to Cathode. An Open vise versa.

I tested it with a Diode tester and instead of a voltage drop it tells me it's open.

Okay, no big deal, my transformer or cap probably blew the diode.

So I check the other new one and it's also open both ways. So either I'm testing the diodes wrong or got two faulty "new" diodes.

What do the Late Night Electronic technicians of the OT think?
Posted by BRgetthenet
Member since Oct 2011
117728 posts
Posted on 2/20/14 at 11:33 pm to
Peanut butter
Posted by upgrayedd
Lifting at Tobin's house
Member since Mar 2013
134871 posts
Posted on 2/20/14 at 11:35 pm to
Just go buy a new vibrator instead of trying to fix the old one. They're not that expensive.
Posted by Napoleon
Kenna
Member since Dec 2007
69140 posts
Posted on 2/20/14 at 11:38 pm to
quote:

Just go buy a new vibrator instead of trying to fix the old one. They're not that expensive.



swing and a miss there buddy.
Posted by FLBooGoTigs1
Nocatee, FL.
Member since Jan 2008
54578 posts
Posted on 2/20/14 at 11:38 pm to
Wut?

Just get a new one whatever you are talking about gheez
Posted by DoctorTechnical
Baton Rouge
Member since Jul 2009
2797 posts
Posted on 2/20/14 at 11:39 pm to
Somehow this seems appropriate

So now what exactly was arcing from where to where?
Posted by THRILLHO
Metry, LA
Member since Apr 2006
49517 posts
Posted on 2/20/14 at 11:41 pm to
quote:

So I check the other new one and it's also open both ways. So either I'm testing the diodes wrong or got two faulty "new" diodes.



Or your tester isn't putting out a high enough voltage to exceed the threshold voltage of the diodes, in which case it would read open both ways.
Posted by Napoleon
Kenna
Member since Dec 2007
69140 posts
Posted on 2/20/14 at 11:55 pm to
quote:

Or your tester isn't putting out a high enough voltage to exceed the threshold voltage of the diodes, in which case it would read open both ways.



this is what I am leaning towards.
Just my tech data all says to do a test from Anode to Cathode and then reverse it.

The systems is in a microwave and goes up to 3,000 volts. That's what is applied to the Diode which gives it a path from ground. When a microwave buzzes loud, usually its a bad diode.

I already swapped the magnetron and the Transformer to see.
Maybe I'll try a different magnetron.

After this, my company will no longer work on Microwaves. They just aren't worth the headache. Easily the most complicated of appliances.
Posted by Napoleon
Kenna
Member since Dec 2007
69140 posts
Posted on 2/21/14 at 12:03 am to
was thinking could measure the voltage drop with a set up like this.



I'm not 100% though.

Jeez this is killing me.

I know I'm getting 120 volts to transformer and I am getting 2,000 Vdc at the capacitor.
I don't want to be doing too much testing with the power on as this literally can kill me, and then the $250 won't be worth a thing. .lol
This post was edited on 2/21/14 at 12:04 am
Posted by 42
Member since Apr 2012
3703 posts
Posted on 2/21/14 at 12:13 am to
If you have similar diodes to test, you can test your tester on them.

Beyond that, the diode could be bad. Construction?

Can you jump it into a system with a little more juice to see if it performs well? Basically, use another system as a test light.

ETA: I'm no EE, but I always think of diodes as a one way valve for charge (so, current). Dorking around with potential differences when all that semiconductor and state dependence / quantum voodoo is going on puts me in a loop. Ergo, my thought process behind finding a basic way to test the one-way-ness of current flow rather than focus on potential differences. I figured that could be of more help or entertainment than my suggestion itself.
This post was edited on 2/21/14 at 12:19 am
Posted by Napoleon
Kenna
Member since Dec 2007
69140 posts
Posted on 2/21/14 at 12:15 am to
Okay, my Meter didn't have enough voltage.

This redneck on youtube just taught me how to test it.

LINK
Posted by lyande1
p-ville
Member since Jun 2007
400 posts
Posted on 2/21/14 at 12:45 am to
was gonna tell you to boost the voltage, but redneck dude is much smarter than he sounds. kudos to him and good luck to you.
Posted by Legendary0903
Tree Fiddy Green Money
Member since Jan 2014
4416 posts
Posted on 2/21/14 at 1:19 am to
My mind saw "Dildo Testers" in the thread title. I am tired and that was a bit of wishful thinking; howerver, I am dissappointed.
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