From: Clint Jay <cjaysharp@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 21 Jan 2020 01:33:35 -0800
Subject: Re: [EE] Diode bridge failure
Thread-Topic: [EE] Diode bridge failure
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I've seen "odd" failures like this from faulty wiring, an arcing neutral
connection in particular, if it's just one machine then I'd strongly
suggest the on site tech checks the mains feed back to wherever it's common
with other machines that are working reliably at the very least.

On Tue, 21 Jan 2020, 07:04 David Duffy (AVD), <
david@audiovisualdevices.com.au> wrote:

> I was thinking the same at first, but there are several machines in the
> same location running off the same 240V power source and only one is
> blowing the monitoring board.  It's still a poor design of course.
> Hopefully the site tech will change out the transformer and we'll soon
> know if that was the cause.
> David...
>
> On 21/01/2020 4:05 pm, Harold Hallikainen wrote:
> > Interesting case! I had a situation where a device had a bridge made wi=
th
> > 400PIV diodes. It was powered by an external 24VAC transformer. The
> diodes
> > would occasionally fail. These were used in movie theaters and a spike =
of
> > several hundred volts to ground would appear on the transformer seconda=
ry
> > (common mode, not differential) when a xenon lamp in a projector was
> > struck. This would occasionally blow the diodes.
> >
> > Recognizing you have an MOV there to suppress such transients, but I
> > wonder if enough of the transient could still get to the diodes.
> >
>
> --
> ___________________________________________
> David Duffy        Audio Visual Devices P/L
> Unit 8, 10 Hook St, Capalaba 4157 Australia
> Ph: +61 7 38235717      Fax: +61 7 38234717
> Our Web Site: www.audiovisualdevices.com.au
> ___________________________________________
>
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