Questions tagged [failure-analysis]

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How to open hermetic TO packages?

I would like to open a TO-18 can to look at die-bonding/heatsinking and do some electrical experiments with increased airflow. Is there a non-destructive way to do this? My only thought is to drill a ...
bobuhito's user avatar
  • 492
2 votes
1 answer
141 views

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 ...
anatol's user avatar
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9 votes
2 answers
818 views

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)....
Sandro's user avatar
  • 7,099
11 votes
3 answers
3k views

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 ...
Reid's user avatar
  • 119
5 votes
1 answer
400 views

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. ...
Rocketmagnet's user avatar
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0 votes
3 answers
186 views

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 ...
user1228123's user avatar
1 vote
4 answers
306 views

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-...
Torsten Knodt's user avatar
0 votes
1 answer
629 views

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 ...
benpro's user avatar
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4 votes
4 answers
4k views

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 ...
riedaug's user avatar
  • 45
0 votes
4 answers
203 views

What factors could have caused the ceramic capacitors on this board to crack?

While examining an old VGA card for faults under a microscope I found that all of the ceramic capacitors had cracked. The card is circa 1991 so it does have some age on it. But I wouldn't expect solid ...
Zhro's user avatar
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3 votes
2 answers
565 views

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 ...
ROUGEXIII's user avatar
  • 177
0 votes
0 answers
334 views

Are these Zener diodes bad?

I am diode testing Zener diodes and getting conduction in both directions. Does this mean that the diodes are bad or is the diode test just allowing the breakdown voltage to be reached thus causing ...
Stephen Brown's user avatar
1 vote
0 answers
192 views

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 ...
Firewolf's user avatar
0 votes
0 answers
198 views

Hot Swap Controller what could've gone wrong

Back at it again, now with four hot-swap controller implementations that somehow broke down. I've got four of the circuits pointed out below on a PCB next to each other. All four circuits are powered ...
Mart's user avatar
  • 326
1 vote
1 answer
114 views

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 ...
jani's user avatar
  • 19
1 vote
1 answer
107 views

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 ...
ericnutsch's user avatar
13 votes
4 answers
3k views

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. ...
Sod Almighty's user avatar
  • 1,324
8 votes
4 answers
4k views

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 ...
jwsc's user avatar
  • 806
0 votes
1 answer
182 views

Is is possible to calculate the MTBF or Failure rate from a given datasheet when manufacturer have not given these details?

As there are new components getting added to the mouser or digikey, is it possible to calculate the failure rate based on some pre known facts and values? some vendors don't reply for weeks and I can'...
Sachin Attri's user avatar
0 votes
1 answer
4k views

MTBF / MTTF and parallel systems

I'm doing an MTBF calculation for a system. Basically I calculated or searched for the MTBFs / FITs of every component. Then added up the FITs and got the total MTBF. My first question would be the ...
alexanzi's user avatar
0 votes
0 answers
171 views

Reasons for filament LED bulb failure?

I recently purchased a filament LED bulb. However, when installed (AC 220V), it wasn't working well: it had a very low light. But sometimes (~ every 5min) it lights up for a few seconds at its normal ...
yO_'s user avatar
  • 101
1 vote
1 answer
133 views

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 ...
Edgar Brown's user avatar
  • 8,416