High voltage problem

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1 month 2 weeks ago #11103 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic High voltage problem
Your test circuit looks exactly right.

Look into it later when the dust is clearing off the crater.

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1 month 2 weeks ago #11104 by Ian
Replied by Ian on topic High voltage problem
Sorry I'm a bit hard to get hold of at the moment, I am holding a training course in the middle east.

Sounds to me like this is probably best to go for the "back to base" option and I'll figure it out on the bench, and fix it or replace it.

Does that sound acceptable?

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1 month 2 weeks ago #11105 by RNi
Replied by RNi on topic High voltage problem
Gentlemen,
@Ty_Eberfest Thanks for all your comments.
@Ian it's totally fine for me.
But please wait one more day until we take some decision about shipping anything....
Today my local electronic shop promised me to order for me IRF640 - should be here tomorrow. Let's check if replacing it by new one will do the job

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1 month 2 weeks ago #11106 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic High voltage problem
RNi - I think that's a good plan. If I am right about it being the IRF640 (I'm 90% sure) then you will have it working immediately instead of having to wait for international shipping and everything. Let us know how it goes!

Ian - Thanks for having a look at this thread. I didn't want to suggest "back to base" until you had seen what we've been doing. You're a long way from home! Be safe.

Look into it later when the dust is clearing off the crater.

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1 month 2 weeks ago - 1 month 2 weeks ago #11107 by Torsten Lang
Replied by Torsten Lang on topic High voltage problem
Hello RNi,
when you exchange the IRF640 take care of static electricity. These parts don't have any gate protection and are rated for a Gate to Source voltage of +/-20V max. which can easily be reached.

As these Power MOSFETs have a higher gate capacitance than high frequency FETs it will take more Coulombs to reach the critical voltage but nevertheless keep in mind that there is no protection, so you have to take some care!

I don't know which ESD precautions you take when working with such parts...

Regards,
Torsten
Last edit: 1 month 2 weeks ago by Torsten Lang.

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1 month 2 weeks ago #11108 by RNi
Replied by RNi on topic High voltage problem
Good evening,

Just got 2 pcs (1 extra just in case) of IRF640.

Connected to test circuit provided by Ty_Eberfest works exactly how it was described :-) Good news !!!

At weekend I'll clean up a little bit soldering points on the main board and do finall test of high voltage.

Crossed fingers !!!

@Torsten I use only basic ESD protection - some band on my hand connected to the radiator in my room (see attached)
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