damaged by lightning

[PA3040]

Dear All,

This question only for understanding purpose

Last week my printer get damaged by lightning. (lightning damage).

My PC connected to Printer via USB cable
Both connected to main power source ( 230v 50Hz)

Printer has mother board and printer controller board
Printer controller board connected to mother board

I inspected the printer board and it physical damaged surrounds USB connecter.

so I replaced printer board now it is working

My PC has not any damage
I think lightning cumming from PC
Can any body please explain how such thing happen without get damage other parts of PC and printer

Please advice

 

[jpsganesh]

My guess is lightning high impulse voltage might have come from power pins of printer and PC.
From printer power might have gone to PC through USB. PC might get proper protection so it didn’t get damage and grounder all power. So through USB it might made closed path. This may be one of the reason.

 

[PA3040]

Dear jpsganesh Thanks for the reply and suggestion

I would like more suggestion go get close reply

Thanks again and again

 

[FvM]

I would like more suggestion go get close reply

Suggestion for what?
To prevent lightning damage, use staggered overvoltage protection (at the buildings power entrance, at the switch board, at your desktop outlet strip).

For an explanation of damage symptoms, the USB cable shield is directly connected to the metallic case at the PC side but isolated with filter components at the printer side. The filter components are most likely not designed for lightning induced overvoltage persistence. Survival of the other parts surely involves a lot of luck.

 

[ArNvC]

Lightning is an extremely powerful electrical force which can jump across switch contacts and take out a device even when it’s turned off. The only way to truly protect your computer equipment from an impending lightning strike is to unplug EVERYTHING that comes into the house from the outside. This includes all power cables, cable Internet wires, satellite wires (if you have a satellite Internet connection), and telephone wires (if you happen to have DSL). The only exception is a fiber optic connection since those are completely immune to power surges.

Can any body please explain how such thing happen without get damage other parts of PC and printer

Seems the power surge went through the USB port. You are lucky that your PC is okay as although computers have a lot of surge protection mechanisms, a lightning strike is anywhere from 1,000 to 100,000 Amperes with rise times measured in microseconds which is too high and fast for most/all surge protectors.

 

[jpsganesh]

the USB cable shield is directly connected to the metallic case at the PC side

Dear FvM, I would like to know if the USB cable doesn't have shield whether it'll be left free or will be connected with -ve power pin of USB supply?



I like these comments

The filter components are most likely not designed for lightning induced overvoltage persistence. Survival of the other parts surely involves a lot of luck.

You are lucky that your PC is okay

 

[PA3040]

For an explanation of damage symptoms, the USB cable shield is directly connected to the metallic case at the PC side but isolated with filter components at the printer side. The filter components are most likely not designed for lightning induced overvoltage persistence. Survival of the other parts surely involves a lot of luck.

Dear FvM really thanks for the reply

In my case the metallic case is directly soldered to PCB common ground and common ground connected to main chassy of the Printer by screws

This is very interesting to collect the ideas therefore hopes more ideas

Thanks
PA3040

 

[jpsganesh]

In my case the metallic case is directly soldered to PCB common ground and common ground connected to main chassy of the Printer by screws

I thought case GND and 0V (USB -ve supply) will be isolated and will be maintained separately.

 

[PA3040]

I thought case GND and 0V (USB -ve supply) will be isolated and will be maintained separately.

-ve mean (-D )

 

[jpsganesh]

-ve mean (-D )

No. USB GND (Digital GND) not -D (-ve data).
I thought Case GND and USB digital GND will be isolated. But from ur previous post I comes to know that both the GND they are mingling it seems.

 

[PA3040]

No. USB GND (Digital GND) not -D (-ve data).
I thought Case GND and USB digital GND will be isolated. But from ur previous post I comes to know that both the GND they are mingling it seems.

May be
I have damaged printer card
First I need to remove the USB socket then find the connectivity and let you know more information's

Thanks for advice

 

[FvM]

I thought Case GND and USB digital GND will be isolated. But from ur previous post I comes to know that both the GND they are mingling it seems.

As said, it's a common practice to tie both USB GND and Shield to ground plane at PCB motherboards. There's no clear suggestion in this regard in the USB specification. As I also mentioned, it's often connected through filter components at the device side. But essentially, there's a direct path between USB ground and device common ground.

If the common ground is also directly connected to chassis and protective earth, as I understand from the reports, then lightning induced overvoltages will cause high current through PE and USB cable. It can be expected to cause damage of the weakest element, e.g. a common mode choke for USB ground.

 

[PA3040]

If the common ground is also directly connected to chassis and protective earth, as I understand from the reports, then lightning induced over voltages will cause high current through PE and USB cable. It can be expected to cause damage of the weakest element, e.g. a common mode choke for USB ground.

I carefully checked my damaged printer PCB,Yes,common ground not directly connected to chassis

Yes, you are correct

I thought case GND and 0V (USB -ve supply) will be isolated and will be maintained separately.

Further I observed that USB GND -Ve not connected to protective earth ground ( Chassis ) but it is directly connected to common GND. Common & protective earth are connected by few resistor's in several locations and further I observed that metallic case also directly connected to Protective ground

In above symptom can we have more ideas

also I sow like other PBC's in this PCB ( 94v-0 E133472 ). Could you please advice on this regard

Please advice
Thanks in advance

 

[jpsganesh]

Further I observed that USB GND -Ve not connected to protective earth ground ( Chassis ) but it is directly connected to common GND. Common & protective earth are connected by few resistor's in several locations and further I observed that metallic case also directly connected to Protective ground

Very good statement Mr.PA3040

Those resistors will not be normal resistor. It may be fusible resistor or MOV type.

 

[PA3040]

Very good statement Mr.PA3040

Those resistors will not be normal resistor. It may be fusible resistor or MOV type.

Yes May be the value maintion on the resistor is 0 ( SMD type resistor ).

Dear Do you know the meaning of this ( 94v - 0 E133472 )

Thanks

 

[jpsganesh]

Dude that is not a single part no. split it in to two.

because 94V-0 is PCB quality for UL certification.

Ref: - really very good doc

Ex test report: **broken link removed**

E133472 also standard related term.
Wiring, Printed - Component
Ref: ZPMV2E328445 Wiring Printed ComponentE328445 Wiring Printed Component pdf free ebook download from www.esskabel.de
http://ebookbrowse.com/zpmv2e328445...28445-wiring-printed-component-pdf-d290391544