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Abusing brick on the rope

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  Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-02 12:55 -0700
    Re: Abusing brick on the rope tabbypurr@gmail.com - 2018-10-02 13:12 -0700
      Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-02 13:35 -0700
        Re: Abusing brick on the rope tabbypurr@gmail.com - 2018-10-02 16:13 -0700
          Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-02 17:04 -0700
            Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-02 17:19 -0700
              Re: Abusing brick on the rope tabbypurr@gmail.com - 2018-10-02 17:47 -0700
              Re: Abusing brick on the rope Lasse Langwadt Christensen <langwadt@fonz.dk> - 2018-10-02 18:16 -0700
              Re: Abusing brick on the rope Jon Elson <elson@pico-systems.com> - 2018-10-03 14:09 -0500
                Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 17:37 -0700
                Re: Abusing brick on the rope <698839253X6D445TD@nospam.org> - 2018-10-04 06:19 +0000
        Re: Abusing brick on the rope DLUNU <DecadentLinuxUserNumeroUno@DLU.org> - 2018-10-03 01:47 +0000
          Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 06:11 -0700
            Re: Abusing brick on the rope Steve Wilson <no@spam.com> - 2018-10-03 13:17 +0000
              Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 06:36 -0700
                Re: Abusing brick on the rope gnuarm.deletethisbit@gmail.com - 2018-10-03 10:02 -0700
                Re: Abusing brick on the rope krw@notreal.com - 2018-10-03 22:14 -0400
              Re: Abusing brick on the rope DLUNU <DecadentLinuxUserNumeroUno@DLU.org> - 2018-10-03 16:27 +0000
                Re: Abusing brick on the rope gnuarm.deletethisbit@gmail.com - 2018-10-03 10:04 -0700
            Re: Abusing brick on the rope DLUNU <DecadentLinuxUserNumeroUno@DLU.org> - 2018-10-03 16:25 +0000
    Re: Abusing brick on the rope piglet <erichpwagner@hotmail.com> - 2018-10-02 21:25 +0100
      Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-02 13:48 -0700
        Re: Abusing brick on the rope Jon Elson <elson@pico-systems.com> - 2018-10-03 14:15 -0500
          Re: Abusing brick on the rope Phil Allison <pallison49@gmail.com> - 2018-10-03 15:18 -0700
            Re: Abusing brick on the rope tabbypurr@gmail.com - 2018-10-03 17:26 -0700
              Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 17:52 -0700
            Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 17:45 -0700
            Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-11 12:22 -0700
    Re: Abusing brick on the rope John Robertson <spam@flippers.com> - 2018-10-02 15:32 -0700
    Re: Abusing brick on the rope Lasse Langwadt Christensen <langwadt@fonz.dk> - 2018-10-02 15:56 -0700
    Re: Abusing brick on the rope Jasen Betts <jasen@xnet.co.nz> - 2018-10-03 00:58 +0000
    Re: Abusing brick on the rope Phil Allison <pallison49@gmail.com> - 2018-10-02 23:23 -0700
      Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 06:16 -0700
    Re: Abusing brick on the rope Phil Allison <pallison49@gmail.com> - 2018-10-02 23:25 -0700
    Re: Abusing brick on the rope <698839253X6D445TD@nospam.org> - 2018-10-03 07:30 +0000
      Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 06:19 -0700
        Re: Abusing brick on the rope <698839253X6D445TD@nospam.org> - 2018-10-03 14:01 +0000
          Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 07:12 -0700
            Re: Abusing brick on the rope <698839253X6D445TD@nospam.org> - 2018-10-04 06:20 +0000
      Re: Abusing brick on the rope Jon Elson <elson@pico-systems.com> - 2018-10-03 14:20 -0500
        Re: Abusing brick on the rope Lasse Langwadt Christensen <langwadt@fonz.dk> - 2018-10-03 12:27 -0700
          Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 17:58 -0700
            Re: Abusing brick on the rope <698839253X6D445TD@nospam.org> - 2018-10-04 06:20 +0000
        Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 17:36 -0700
    Re: Abusing brick on the rope Mikko OH2HVJ <mikko.syrjalahti@nospam.fi> - 2018-10-03 12:39 +0300
      Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 06:22 -0700
    Re: Abusing brick on the rope Ingvald44 <noone@nowhere.com> - 2018-10-03 08:02 -0400
    Re: Abusing brick on the rope Jon Elson <elson@pico-systems.com> - 2018-10-03 14:07 -0500
      Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-03 17:24 -0700
        Re: Abusing brick on the rope Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2018-10-04 12:45 -0400
          Re: Abusing brick on the rope George Herold <gherold@teachspin.com> - 2018-10-04 10:01 -0700

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#518149

On 02/10/2018 20:55, George Herold wrote:
> Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor
> LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm
> resistor in series.  (the zener stops it from turning on if one of the rails
> fails.)  It just barley put out any light.... trashed.
> It can take 30 mA forward so >~150 V for too much current.
> And in reverse it doesn't break down till -80 V.
> (I just tested it... it shows a photo response too,
> but don't distract me.)
> 
> So I was in contact with the school that was using this.. checking return
> address, and I asked if they wanted a new brick on the rope.  (Because they
> hadn't returned theirs with the unit.)  It was just then that I learned that
> the brick on the rope had failed!!  And they had purchased a new one from the
> vendor (astrodyne)
> 
> So my current theory is that the brick on the rope failed (somehow)
> and blew 120 Vac through my circuit.. with devastating results.
> Any idea how I can test this theory.. how do I blow up a brick on a
> rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.
> 
> Thanks
> George H.
> (maybe I should contact astrodyne.)
> 

I have seen a LED become dim after being exposed to episodes of reverse 
polarity. In the case I saw it was spikes of 18-30V (so well above the 
5V usually seen for Vr on LED datasheets). The first few zaps seemed to 
have no effect but damage must have built up.

If that is a SMPS then 120V 60Hz appearing on the output seems unlikely 
but if an output rectifier shorts then spikes of reverse HV at the 
switching frequency could explain what you saw?

piglet

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#518152

On Tuesday, October 2, 2018 at 4:26:11 PM UTC-4, piglet wrote:
> On 02/10/2018 20:55, George Herold wrote:
> > Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor
> > LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm
> > resistor in series.  (the zener stops it from turning on if one of the rails
> > fails.)  It just barley put out any light.... trashed.
> > It can take 30 mA forward so >~150 V for too much current.
> > And in reverse it doesn't break down till -80 V.
> > (I just tested it... it shows a photo response too,
> > but don't distract me.)
> > 
> > So I was in contact with the school that was using this.. checking return
> > address, and I asked if they wanted a new brick on the rope.  (Because they
> > hadn't returned theirs with the unit.)  It was just then that I learned that
> > the brick on the rope had failed!!  And they had purchased a new one from the
> > vendor (astrodyne)
> > 
> > So my current theory is that the brick on the rope failed (somehow)
> > and blew 120 Vac through my circuit.. with devastating results.
> > Any idea how I can test this theory.. how do I blow up a brick on a
> > rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.
> > 
> > Thanks
> > George H.
> > (maybe I should contact astrodyne.)
> > 
> 
> I have seen a LED become dim after being exposed to episodes of reverse 
> polarity. In the case I saw it was spikes of 18-30V (so well above the 
> 5V usually seen for Vr on LED datasheets). The first few zaps seemed to 
> have no effect but damage must have built up.
> 
> If that is a SMPS then 120V 60Hz appearing on the output seems unlikely 
> but if an output rectifier shorts then spikes of reverse HV at the 
> switching frequency could explain what you saw?
> 
> piglet

Right, last night I was thinking just a reverse voltage would do it.  
(I was picturing some burly student cramming in the power plug the wrong
way.)  
So I tested the LED here... it takes 80 V of Vrev.  (And then seems to turn 
into another dang spad.) It's happy sitting at -40V for several hours 

Spikes at the switching frequency would explain some of the damage, but 
there is one section that has an LC filter on the power lines and that 
should have taken care of the ~100 kHz switching freq.  There is the 
same LED as indicator on that section of circuit.  (Oh... checks 
schematic) The led is before filter.. So your theory stands.  

I wish I'd heard about the failed SMPS before today... I'll ask more 
questions... maybe they still have the failed unit and I could do an 
autopsy.  

George H.  

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#518233

On Tue, 02 Oct 2018 13:48:17 -0700, George Herold wrote:


> I wish I'd heard about the failed SMPS before today... I'll ask more
> questions... maybe they still have the failed unit and I could do an
> autopsy.
Well, most SMPS's have some small capacitor bridging from the primary 
side to the secondary side of the transformer, to drain the pulses 
coupled across the primary-secondary capacitance.  If this cap fails, and 
any part of the powered equipment is connected outside, it can cause a 
shock hazard or excessive current draw.  If lightning hits the mains, it 
WILL cause high voltage on the equipment, and if that gear is connected 
to anything grounded, there's not much limit to the current available.

Jon

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#518257

Jon Elson wrote:
> 
>
> Well, most SMPS's have some small capacitor bridging from the primary 
> side to the secondary side of the transformer, to drain the pulses 
> coupled across the primary-secondary capacitance.  If this cap fails,
>


** It should be pointed out that such caps are required by regulation to be special class Y types of strictly limited values - like 1000pF or 2200pF. 

Failures are extremely rare.

Wait till GH gets to actually examine the "brick on a rope" concerned.

It just might turn out to have nothing wrong with t. 


....  Phil

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#518276

On Wednesday, 3 October 2018 23:19:04 UTC+1, Phil Allison  wrote:

> Wait till GH gets to actually examine the "brick on a rope" concerned.

+1, until then it's guesses.


NT

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#518283

On Wednesday, October 3, 2018 at 8:26:25 PM UTC-4, tabb...@gmail.com wrote:
> On Wednesday, 3 October 2018 23:19:04 UTC+1, Phil Allison  wrote:
> 
> > Wait till GH gets to actually examine the "brick on a rope" concerned.
> 
> +1, until then it's guesses.
> 
> 
> NT

If it is the supply, then I'm hoping for help IDing the 
failed bit... with pics of course.  

GH

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#518282

On Wednesday, October 3, 2018 at 6:19:04 PM UTC-4, Phil Allison wrote:
> Jon Elson wrote:
> > 
> >
> > Well, most SMPS's have some small capacitor bridging from the primary 
> > side to the secondary side of the transformer, to drain the pulses 
> > coupled across the primary-secondary capacitance.  If this cap fails,
> >
> 
> 
> ** It should be pointed out that such caps are required by regulation to be special class Y types of strictly limited values - like 1000pF or 2200pF. 
> 
> Failures are extremely rare.
> 
> Wait till GH gets to actually examine the "brick on a rope" concerned.
> 
> It just might turn out to have nothing wrong with t. 
Absolutely right!  Still, I'd bet there's some bad spikes 
somewhere... or lightning.
George H. 
> 
> 
> ....  Phil

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#518991

On Wednesday, October 3, 2018 at 6:19:04 PM UTC-4, Phil Allison wrote:
> Jon Elson wrote:
> > 
> >
> > Well, most SMPS's have some small capacitor bridging from the primary 
> > side to the secondary side of the transformer, to drain the pulses 
> > coupled across the primary-secondary capacitance.  If this cap fails,
> >
> 
> 
> ** It should be pointed out that such caps are required by regulation to be special class Y types of strictly limited values - like 1000pF or 2200pF. 
> 
> Failures are extremely rare.
> 
> Wait till GH gets to actually examine the "brick on a rope" concerned.
> 
> It just might turn out to have nothing wrong with t. 
> 
> 
> ....  Phil

Well I just wanted to report that Phil A. wins the prize*.  I got the 
power supply back today, and with a quick look all appears perfectly 
fine.  (50 ohm load, +/-15 V @~ 1A.)  I'll try a heavier load tomorrow
and then some abuse... but this puppy looks fine.  

George h. 
*not sure what the prize is, maybe he can put a gold star on his frig. 

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#518156

On 2018/10/02 12:55 PM, George Herold wrote:
> Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor
> LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm
> resistor in series.  (the zener stops it from turning on if one of the rails
> fails.)  It just barley put out any light.... trashed.
> It can take 30 mA forward so >~150 V for too much current.
> And in reverse it doesn't break down till -80 V.
> (I just tested it... it shows a photo response too,
> but don't distract me.)
> 
> So I was in contact with the school that was using this.. checking return
> address, and I asked if they wanted a new brick on the rope.  (Because they
> hadn't returned theirs with the unit.)  It was just then that I learned that
> the brick on the rope had failed!!  And they had purchased a new one from the
> vendor (astrodyne)
> 
> So my current theory is that the brick on the rope failed (somehow)
> and blew 120 Vac through my circuit.. with devastating results.
> Any idea how I can test this theory.. how do I blow up a brick on a
> rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.
> 
> Thanks
> George H.
> (maybe I should contact astrodyne.)
> 

Power line lightning strike? Was any other equipment in the school 
damaged or destroyed at the same time?

Astrodyne claims 3KV isolation between line and output...

John :-#(#

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#518157

tirsdag den 2. oktober 2018 kl. 21.56.03 UTC+2 skrev George Herold:
> Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor 
> LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
> resistor in series.  (the zener stops it from turning on if one of the rails 
> fails.)  It just barley put out any light.... trashed.  
> It can take 30 mA forward so >~150 V for too much current.  
> And in reverse it doesn't break down till -80 V. 
> (I just tested it... it shows a photo response too, 
> but don't distract me.) 
> 
> So I was in contact with the school that was using this.. checking return 
> address, and I asked if they wanted a new brick on the rope.  (Because they 
> hadn't returned theirs with the unit.)  It was just then that I learned that 
> the brick on the rope had failed!!  And they had purchased a new one from the 
> vendor (astrodyne)  
> 
> So my current theory is that the brick on the rope failed (somehow) 
> and blew 120 Vac through my circuit.. with devastating results.  
> Any idea how I can test this theory.. how do I blow up a brick on a 
> rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.  
> 

no GFCI? else I think you need two short to happen at the same time to get 
full mains on the output which I don't think is very likely

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#518167

On 2018-10-02, George Herold <gherold@teachspin.com> wrote:
> Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor 
> LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
> resistor in series.  (the zener stops it from turning on if one of the rails 
> fails.)  It just barley put out any light.... trashed.  
> It can take 30 mA forward so >~150 V for too much current.  
> And in reverse it doesn't break down till -80 V. 
> (I just tested it... it shows a photo response too, 
> but don't distract me.) 
>
> So I was in contact with the school that was using this.. checking return 
> address, and I asked if they wanted a new brick on the rope.  (Because they 
> hadn't returned theirs with the unit.)  It was just then that I learned that 
> the brick on the rope had failed!!  And they had purchased a new one from the 
> vendor (astrodyne)  

what if they substituted a lab powersupply for the broken brick, but
fouled that up somehow?

-- 
     ت

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#518175

George Herold wrote:
>
>
> Hi all, I just got done fixing a piece of apparatus that was returned to us. 
> The thing was trashed, (all sorts of blown components) and I've been trying
> to figure out what happened.  Perhaps what I found weirdest is a power
> monitor  LED. 
> This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
> resistor in series.  (the zener stops it from turning on if one of the rails 
> fails.)  It just barley put out any light.... trashed.  
> It can take 30 mA forward so >~150 V for too much current.  
> And in reverse it doesn't break down till -80 V. 
> 
> So I was in contact with the school that was using this..
>

 ** I hear alarm bell going off.....  



> checking return 
> address, and I asked if they wanted a new brick on the rope.  (Because they 
> hadn't returned theirs with the unit.)  It was just then that I learned that 
> the brick on the rope had failed!!  And they had purchased a new one from the 
> vendor (astrodyne)  
> 
> So my current theory is that the brick on the rope failed (somehow) 
> and blew 120 Vac through my circuit.. with devastating results.  
> Any idea how I can test this theory.. how do I blow up a brick on a 
> rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.  
>

** There are any number of ways  -  one I had to deal with involved a badly damaged analog synthesiser ( keyboard instrument ) that had vaporised ground tracks and 30 odd blown small components, bead tantalums, diodes CMOSs ICs etc. 

I later learned it had been briefly powered from a wrongly wired extension lead with ground & active swapped and connected to a normally earthed valve amp. Bang.

In your case, the device and the "brick" would likely both be seriously damaged, assuming earth is carried trough to the outlet.


....    Phil 

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#518194

On Wednesday, October 3, 2018 at 2:23:28 AM UTC-4, Phil Allison wrote:
> George Herold wrote:
> >
> >
> > Hi all, I just got done fixing a piece of apparatus that was returned to us. 
> > The thing was trashed, (all sorts of blown components) and I've been trying
> > to figure out what happened.  Perhaps what I found weirdest is a power
> > monitor  LED. 
> > This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
> > resistor in series.  (the zener stops it from turning on if one of the rails 
> > fails.)  It just barley put out any light.... trashed.  
> > It can take 30 mA forward so >~150 V for too much current.  
> > And in reverse it doesn't break down till -80 V. 
> > 
> > So I was in contact with the school that was using this..
> >
> 
>  ** I hear alarm bell going off.....  
> 
> 
> 
> > checking return 
> > address, and I asked if they wanted a new brick on the rope.  (Because they 
> > hadn't returned theirs with the unit.)  It was just then that I learned that 
> > the brick on the rope had failed!!  And they had purchased a new one from the 
> > vendor (astrodyne)  
> > 
> > So my current theory is that the brick on the rope failed (somehow) 
> > and blew 120 Vac through my circuit.. with devastating results.  
> > Any idea how I can test this theory.. how do I blow up a brick on a 
> > rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.  
> >
> 
> ** There are any number of ways  -  one I had to deal with involved a badly damaged analog synthesiser ( keyboard instrument ) that had vaporised ground tracks and 30 odd blown small components, bead tantalums, diodes CMOSs ICs etc. 
> 
> I later learned it had been briefly powered from a wrongly wired extension lead with ground & active swapped and connected to a normally earthed valve amp. Bang.
> 
> In your case, the device and the "brick" would likely both be seriously damaged, assuming earth is carried trough to the outlet.
> 
> 
> ....    Phil

Re: ground.  Yeah the shell/shield of the supply is connected to earth.  
Inside the unit I connect 'earth' to ground with a 10 ohm/ 1/2 W resistor.  
This was undamaged in the returned unit.  So I'm assuming no weird 
ground thing.  (but only assuming...) 

george H.   

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#518176

George Herold wrote:
>
>
> Hi all, I just got done fixing a piece of apparatus that was returned to us. 
> The thing was trashed, (all sorts of blown components) and I've been trying
> to figure out what happened.  Perhaps what I found weirdest is a power
> monitor  LED. 
> This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
> resistor in series.  (the zener stops it from turning on if one of the rails 
> fails.)  It just barley put out any light.... trashed.  
> It can take 30 mA forward so >~150 V for too much current.  
> And in reverse it doesn't break down till -80 V. 
> 
> So I was in contact with the school that was using this..
>

 ** I hear alarm bell going off.....  



> checking return 
> address, and I asked if they wanted a new brick on the rope.  (Because they 
> hadn't returned theirs with the unit.)  It was just then that I learned that 
> the brick on the rope had failed!!  And they had purchased a new one from the 
> vendor (astrodyne)  
> 
> So my current theory is that the brick on the rope failed (somehow) 
> and blew 120 Vac through my circuit.. with devastating results.  
> Any idea how I can test this theory.. how do I blow up a brick on a 
> rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.  
>

** There are any number of ways  -  one I had to deal with involved a badly damaged analog synthesiser ( keyboard instrument ) that had vaporised ground tracks and 30 odd blown small components, bead tantalums, diodes CMOSs ICs etc. 

I later learned it had been briefly powered from a wrongly wired extension lead with ground & active swapped and connected to a normally earthed valve amp. Bang.

In your case, the device and the "brick" would likely both be seriously damaged, assuming earth is carried trough to the outlet.


....    Phil 

[toc] | [prev] | [next] | [standalone]

#518178

George Herold wrote
>Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown
>components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor 
>LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
>resistor in series.  (the zener stops it from turning on if one of the rails 
>fails.)  It just barley put out any light.... trashed.  
>It can take 30 mA forward so >~150 V for too much current.  
>And in reverse it doesn't break down till -80 V. 
>(I just tested it... it shows a photo response too, 
>but don't distract me.) 
>
>So I was in contact with the school that was using this.. checking return 
>address, and I asked if they wanted a new brick on the rope.  (Because they 
>hadn't returned theirs with the unit.)  It was just then that I learned that 
>the brick on the rope had failed!!  And they had purchased a new one from the 
>vendor (astrodyne)  
>
>So my current theory is that the brick on the rope failed (somehow) 
>and blew 120 Vac through my circuit.. with devastating results.  
>Any idea how I can test this theory.. how do I blow up a brick on a 
>rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.  
>
>Thanks
>George H. 
>(maybe I should contact astrodyne.)       

It being a school, it would not surprise me (has your 'thing' any output? if
'they' (accidently??) put some ...mains into your output and that way in reverse killed your
unit and that power supply (a more common word) too.
He 'whodiddit' will remain anonymous and life goes on.
In that worst case they will do it again with the new replacement.
From a legal POV you can use an expert witness to show your thing could not be the cause.
Shit situation.

 Not enough data

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#518196

On Wednesday, October 3, 2018 at 3:30:50 AM UTC-4, 69883925...@nospam.org wrote:
> George Herold wrote
> >Hi all, I just got done fixing a piece of apparatus that was returned to us.  The thing was trashed, (all sorts of blown
> >components) and I've been trying to figure out what happened.  Perhaps what I found weirdest is a power monitor 
> >LED.  This sits across the +/-15 V rails, with a 12V zener and 5 k ohm 
> >resistor in series.  (the zener stops it from turning on if one of the rails 
> >fails.)  It just barley put out any light.... trashed.  
> >It can take 30 mA forward so >~150 V for too much current.  
> >And in reverse it doesn't break down till -80 V. 
> >(I just tested it... it shows a photo response too, 
> >but don't distract me.) 
> >
> >So I was in contact with the school that was using this.. checking return 
> >address, and I asked if they wanted a new brick on the rope.  (Because they 
> >hadn't returned theirs with the unit.)  It was just then that I learned that 
> >the brick on the rope had failed!!  And they had purchased a new one from the 
> >vendor (astrodyne)  
> >
> >So my current theory is that the brick on the rope failed (somehow) 
> >and blew 120 Vac through my circuit.. with devastating results.  
> >Any idea how I can test this theory.. how do I blow up a brick on a 
> >rope?  (Astrodyne Mod num. SPU45-210) +15 V @ +2A / -15V @ -1A.  
> >
> >Thanks
> >George H. 
> >(maybe I should contact astrodyne.)       
> 
> It being a school, it would not surprise me (has your 'thing' any output? if
> 'they' (accidently??) put some ...mains into your output and that way in reverse killed your
> unit and that power supply (a more common word) too.
> He 'whodiddit' will remain anonymous and life goes on.
> In that worst case they will do it again with the new replacement.
> From a legal POV you can use an expert witness to show your thing could not be the cause.
> Shit situation.
> 
>  Not enough data

Right, the data I have says the power supply fried... or was hooked up 
wrong or... But most of the damage was to the PS inputs.  

George H.  

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#518200

George wrote
>On Wednesday, October 3, 2018 at 3:30:50 AM UTC-4, 69883925...@nospam.org wrote:
>> Shit situation.
>> 
>>  Not enough data
>
>Right, the data I have says the power supply fried... or was hooked up 
>wrong or... But most of the damage was to the PS inputs.  

Could it be the + and - were reversed?
That would reverse bias an damage that LED.
Is it one connector, or separate screw terminals?
In the last case do you have (or should you have) diodes in the supply lines?

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#518202

On Wednesday, October 3, 2018 at 10:01:56 AM UTC-4, 69883925...@nospam.org wrote:
> George wrote
> >On Wednesday, October 3, 2018 at 3:30:50 AM UTC-4, 69883925...@nospam.org wrote:
> >> Shit situation.
> >> 
> >>  Not enough data
> >
> >Right, the data I have says the power supply fried... or was hooked up 
> >wrong or... But most of the damage was to the PS inputs.  
> 
> Could it be the + and - were reversed?
> That would reverse bias an damage that LED.
> Is it one connector, or separate screw terminals?
> In the last case do you have (or should you have) diodes in the supply lines?

Right, I thought that till I found the LED's can take 80V in reverse.  
(There are no reverse bias safe guards on the PS input... )  
It's (I think) a DIN 5 connector... I was trying to plug it in backwards 
or sideways, but it was not possible... well very hard.

Hey the professor still has the failed brick on rope, so I'm having that 
sent back.. I'll check it out and then crack it open.   I'll post 
pics if I find anything interesting.  

George H. 

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#518304

George Herold wrote
>It's (I think) a DIN 5 connector... I was trying to plug it in backwards 
>or sideways, but it was not possible... well very hard.

From a design POV, when having a '+', 'GND',  and '-' connection,
then you likely want the ground pin to make contact first.
DIN 5 180 degrees is, in Europe at least, a standard audio connector for consumer audio stuff,
(or was, I see only  3.5 mm phono plugs in the Chinese stuff these days).

The 3 pole XLR (also audio) could work:
from
 https://en.wikipedia.org/wiki/XLR_connector
<quote>
 The female XLR connectors are designed to first connect pin 1 (the earth pin),
 before the other pins make contact, when a male XLR connector is inserted.
 With the ground connection established before the signal lines are connected,
 the insertion (and removal) of XLR connectors in live equipment is possible without picking up external signals (as usually happens with, for example, RCA connectors). 
<end quote>

I am using a 5 pole XLR in that way for my gamma spectrum analyzer probe:
 http://panteltje.com/pub/gamma_spectrometer_supply_side_MG_6578.JPG

I have used the 5 pole 180 degrees DINs to send i2c through the house...
screened audio cable, i2c allows you to set the speed as low as you like..

Always question what will happen if somebody plugs an audio cable in the 5 pole DIN...

Maybe it is often better to get some not so common used connector types,
I have done that for some other high capacity battery powered equipment I designed,
ebay has all sorts of nice connectors.

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#518234

On Wed, 03 Oct 2018 07:30:14 +0000, 698839253X6D445TD wrote:


> It being a school, it would not surprise me (has your 'thing' any
> output? if 'they' (accidently??) put some ...mains into your output and
> that way in reverse killed your unit and that power supply (a more
> common word) too.
> He 'whodiddit' will remain anonymous and life goes on.
> In that worst case they will do it again with the new replacement.
> From a legal POV you can use an expert witness to show your thing could
> not be the cause. Shit situation.
It would not be a bad idea at ALL to have the school check all equipment 
used at that bench or whatever for power supply faults, bad grounds, open 
grounds and whatever.

I got knocked on my rear (literally) by an open ground in my lab at work 
when I had a scope and logic analyzer hooked up, and touched something 
that was connected to my computer on a properly grounded outlet.  I have 
NO IDEA how long the ground on that outlet had been in that condition.

Jon

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