Transient Electrical Discharge (TED): A Destructive Mystery
Transient Electrical Discharge (TED): A Destructive Mystery
(OP)
Greetings all! First time posting and do I have a mystery I could use some insight on. I managing a Technical case where my Company has Tablets installed on forklifts. All the computer tablets have been installed and I'm starting to see Tablets come back into Service.
I take a peek at the Motherboard and each one has some pretty extreme electrical damage. We included a full system; Wire harness (fused, instructions, hardware) mounting for the Tablet and a power adapter. I've rulled out any design flaws in the system- We have been using this on forklifts for over two years.
This install base is different. The quntity of returns with these detroyed componets are growing. I know what the componets are, where it's (whatever the source of the spike) is coming in our system. I just don't know WHERE the source is coming from.
I've included the most common place on the PCB board (taken through a microscope) of a EMI protection componet. Tracing this componet and others damaged in this circuit path lead me to common grounds on the Motherboard.
Again, this in installed on a forklift. This type of damage I've before:
- Lightning
- Transient Electrical Discharge caused by static build up.
The power system is only 19 VCD to power the tablet. This damage was done very fast- The ATC 10A fuse on the power adapter is not blown (but I still see power adapters come in damaged- either the adapter is an open or a full short internally). The Motherboard, the internal fuses are OK, but I've seen some EXTREME damage to some Zener and in line bloking Diodes.
Yes, this damage was done fast with a very high enegy output.
I'm planning a trip to the site. This looks like an issue with grounding. Either the installs were not grounded correctly or maybe the lifts aren't grounded (most forklifts have chains that touch the ground to prevent static buld up.
Any suggestions on what to look for?
My game plan is to test all the grounds, make sure everything has a common ground and see if there's any potensial between grounds. I'll be using my Fluke meter with data logger and my fluke o-scope (200mHZ). Goal with the o-scope is take a peek on power and ground lines and make use of the Spectrum analyzer function (it's just running a FFT on the o-scope input) to see if there's any higher freq spikes that may be adding up. May have a harmonic that rided on the DC line causing a massive spike on the DC offset very quickly. I want to also look at the install to ensure everything is OK
What are some thoughts?
Thanks and really look forward to this disscussion!
I take a peek at the Motherboard and each one has some pretty extreme electrical damage. We included a full system; Wire harness (fused, instructions, hardware) mounting for the Tablet and a power adapter. I've rulled out any design flaws in the system- We have been using this on forklifts for over two years.
This install base is different. The quntity of returns with these detroyed componets are growing. I know what the componets are, where it's (whatever the source of the spike) is coming in our system. I just don't know WHERE the source is coming from.
I've included the most common place on the PCB board (taken through a microscope) of a EMI protection componet. Tracing this componet and others damaged in this circuit path lead me to common grounds on the Motherboard.
Again, this in installed on a forklift. This type of damage I've before:
- Lightning
- Transient Electrical Discharge caused by static build up.
The power system is only 19 VCD to power the tablet. This damage was done very fast- The ATC 10A fuse on the power adapter is not blown (but I still see power adapters come in damaged- either the adapter is an open or a full short internally). The Motherboard, the internal fuses are OK, but I've seen some EXTREME damage to some Zener and in line bloking Diodes.
Yes, this damage was done fast with a very high enegy output.
I'm planning a trip to the site. This looks like an issue with grounding. Either the installs were not grounded correctly or maybe the lifts aren't grounded (most forklifts have chains that touch the ground to prevent static buld up.
Any suggestions on what to look for?
My game plan is to test all the grounds, make sure everything has a common ground and see if there's any potensial between grounds. I'll be using my Fluke meter with data logger and my fluke o-scope (200mHZ). Goal with the o-scope is take a peek on power and ground lines and make use of the Spectrum analyzer function (it's just running a FFT on the o-scope input) to see if there's any higher freq spikes that may be adding up. May have a harmonic that rided on the DC line causing a massive spike on the DC offset very quickly. I want to also look at the install to ensure everything is OK
What are some thoughts?
Thanks and really look forward to this disscussion!





RE: Transient Electrical Discharge (TED): A Destructive Mystery
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Transient Electrical Discharge (TED): A Destructive Mystery
Great input!
Here's another failure as seen through the Microscope.
RE: Transient Electrical Discharge (TED): A Destructive Mystery
The level of damage is consistent with Bill's hypothesis. I've blown chips of that size with connections of hot chassis's to real grounds. If that chip is supposedly an "EMI" component, then it's woefully inadequate for protection against vehicle power. Vehicle power is generally so unclean that there is a MIL-STD just to delineate the minimum requirements needed to protect against it.
TTFN

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RE: Transient Electrical Discharge (TED): A Destructive Mystery
Best to you,
Goober Dave
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RE: Transient Electrical Discharge (TED): A Destructive Mystery
Are these electric (battery powered) forklifts? Or do they have an engine (e.g. propane fuelled)?
RE: Transient Electrical Discharge (TED): A Destructive Mystery
So, we rule out lightning (which I did because these are installed in warehouses) and TED is still questionable. What tests should I be looking into to verify the Load dump hypothisis?
RE: Transient Electrical Discharge (TED): A Destructive Mystery
TTFN

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RE: Transient Electrical Discharge (TED): A Destructive Mystery
RE: Transient Electrical Discharge (TED): A Destructive Mystery
Z
RE: Transient Electrical Discharge (TED): A Destructive Mystery
The second picture 182.jpg appears to be damage to a ceramic capacitor next to what appears to be a flex-circuit connector. There appears to be a burn connection inside the connector. This suggests a LCD display (or keyboard?) that got a severe static zap, or discharge to the outside of the case next to the display that then traveled either into the display or into the flex cable of the display into the main PCB. Static damage to items exposed on the outside of the case (displays, keyboards, I/O ports) is more typical of expected damage.
RE: Transient Electrical Discharge (TED): A Destructive Mystery
RE: Transient Electrical Discharge (TED): A Destructive Mystery
I could only see ONE pix; a small 6 pin IC so no idea what the 'caps damage' stuff is about.
It sure sounds like you will find voltage spikes that are doing the damage.
If batts and not propane, then might be BackEMF from the motors when they decel - I have watched some of the fork lift drives SLIDE their machines across the floor with such maneuvers.
If propane, then chance it is un-suppressed DC solenoids and coils in the machine. I destroyed many transistors before finding a single un-suppresed relay in a machine: simple 1N4004 diode across it fixed it for life.
You will see LOTS of Chevy pickups and SUVs of 2000-ish vintage on the street with only 1 front parking lite lit: un supressed coils killed the filaments for YEARS before GM figured out that on turning off the stupid ignition, coils turned off causing hundreds of volt spikes into those daytime running lites..... I tried to tell them but they would not listen :)
RE: Transient Electrical Discharge (TED): A Destructive Mystery
A load dump could kill lights. But you do not disconnect the battery while running? Do you? Or is there some master DC switch that opens before emgine is turned off?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Transient Electrical Discharge (TED): A Destructive Mystery
RE: Transient Electrical Discharge (TED): A Destructive Mystery
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.