Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [failure-analysis]

21 questions
13
votes
4 answers

Why did this device go bang?

This LED drive module exploded last night, as the result of an earthed (grounded) screw touching a capacitor leg. The breaker (fuse box) tripped, of course, due to earth leakage. That bit makes sense. What I don't get is why there was a massive…
Sod Almighty
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Why did my LED drivers blow up?

I recently designed my first PCB, which houses LED driver circuitry for some custom lighting. I fastidiously followed the driver's datasheet (Diodes Inc AL8862QSP-13) in designing the circuit: making sure the inductor, capacitor, current sense…
Reid
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9
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Burned motor controllers: possible root causes analysis

On a submarine robot we built, during an operation, we recently had 3 defect thruster motors (the internal power PCBs have many burnt components, 2 of the motors cracked open due to internal pressure). Short question: what might have caused it? Do…
Sandro
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Schottky diode failure

TLDR: What are possible failure sources for a schottky diode? Overheating, overvoltage, overcurrent (leading to overheating) anything else? Long version I am currently measuring our new prototype device. It works fine, does not draw more current…
jwsc
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How common is it to receive PCBs with failed or weak vias?

This question is a follow up to Can chips be sensitive to mechanical stress after an electrical incident?. It turns out that our problem was nothing to do with failed chips. It was the PCBs all along. Background: We had a number of flexi-rigid PCBs…
Rocketmagnet
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Did I kill my STM?

I have (had?) an STM32F429ZI. I was working with the ADC on PC0 and due to a hardware malfunction, 12V ran through the pin when the maximum voltage an ADC pin supports is 3V. Since then, whenever I connect the STM to my computer via the USB in CN1,…
riedaug
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Need some help to understand where to start to repair a router damaged by a faulty 12VDC power supply

I have a router that was powered 24h/24. One day the 12 VDC power block died. I made the mistake to replace it with one I get on aliexpress: The aliexpress power block is rated 3 A but when I get it I tested it with a load resistor and it couldn't…
ROUGEXIII
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SMPS Regulator keeps blowing

First Time for me posting here. Recently I decided to perform a recap on an 20 y/o old SMPS, which is used in a digital mixer. The recap went without any complications. I followed the guide I found here: Recapping DDX3126 PSU I also used genuine low…
anatol
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Why can a raclette grill with over 400kOhm resistance between phase and null against earth trigger a 30mA RCD in a 230VAC network?

I have a 1.2kW 230V~1AC raclette grill which triggers 30mA RCDs, probably when the bi-metal temperature controller turns it off. Not to repair, but to get better in failure mode understanding and root-cause analysis, I started to take some…
Torsten Knodt
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Discolored negative lead on electrolytic capacitors

Would the discoloration around the negative lead of these capacitors be a sign of failure? If so, why would the negative lead darken instead of the positive - or both leads. They are Maron EFM 35 volt 680 uF electrolytic capacitors.
Firewolf
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What is the purpose of Failure Mode and Effect Analysis?

Our embedded controller is Advanced Drive Assist Systems(ADAS). It basically has Two software layers. Application software and low-level software. Our controller has many low-level functions such as different communications protocols, different…
jani
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Is it more reliable to connect to both sets of DPDT relay contacts when only SPDT is needed?

I am adding a socket mounted relay to a PCB and only need one set of contacts (SPDT). Does it increase the reliability of the component to connect the both sets of contacts? Are there any other issues this creates? Common practice or bad…
ericnutsch
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Tools/Methodologies for failure mode effect or fault tree analysis (FMEA/FTA)

We have barely started the process towards medical device certification, and as part of that I am having a hard time wrapping my head around the appropriate way to construct a failure mode effect analysis (FMEA) document for a couple of electronic…
Edgar Brown
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PFHD of Dual Redundant Self Checking Circuit

I'm calculating some ridiculous PFHD values for a Dual Redundant Self Checking Circuit and since I'm no expert in reliability calculations (cough) I wanted to check some of the logic. I have two identical, but independent instances of the same…
user1228123
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Form C (SPDT) Relay Failure Modes and Detection

This is a question about the failure modes of an SPDT (i.e. form C) relay. Specifically, I am interested in electromechanical relays for an automotive application. I understand that either contact could be stuck open or stuck closed. But is it…
benpro
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