Author Topic: How long should electronics last  (Read 4324 times)

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Offline Seekonk

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Re: How long should electronics last
« Reply #25 on: December 25, 2017, 12:46:53 am »
There is no conspiracy. It sounds like the input wasn't protected enough and you suffered an extremely rare event.  I got a fairly new dishwasher from a guy who was dropping it off at recycling.  Brought it home and it had taken a massive lightning hit, board was charred and components had exploded in the line voltage section. Certainly this is classified as unrepairable in the service industry. A little clean up and some jumper wires.  Five minutes later it was working.  The microprocessor survived all that.
 

Offline Simon

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Re: How long should electronics last
« Reply #26 on: December 25, 2017, 12:51:56 am »
Well I'm not a conspiracy theorist but sometimes I wonder at how fast stuff breaks down when I am used to designing stuff to be indestructible and last forever. I don't know what rare event could have been suffered. On the whole the thing works as it would run the heating fine but it could no longer control the tap hot water properly reporting a non existent thermistor fault. There is a secondary thermistor apparently but it only controls to 50-55C and this was too low to run the shower that some idiot put on huge pipe sizes (3/4" I think) so a lot of heat is gone by the time the "hot" water gets to the shower head.
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Offline Towger

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Re: How long should electronics last
« Reply #27 on: December 25, 2017, 01:18:11 am »
In my experience 9 years is good for a 'modern' boiler's PCB.  The build quality of Potterton, Glowworm etc is to use the technical term 'shite'.

Simon, it is probably a dry joint or dry capacitor.  I have 3 PCBs for my boiler, of different revisions.

1. Original: I managed to keep this going for 10 years, full of dry joints.  In fact I don't know how it ever worked, a couple of resistor legs were not even soldered.  It eventually decided not to detect a flame.  This was probably a dry capacitor, but after several repairs it was time to go.

2. More modern version,  with LEDs rather than neons.  This lasted two years before it started giving trouble.  A whack with screwdriver would get it going again.  In the words of Tom Baker as Dr Who 'If in douth give it a clout'.  In order to keep SWBMO happy I ordered replacement 3. 
 #2 reached an unusable state before #3 arrived.  Another late night freezing cold, repair job...  It lives outside in a shed.  On inspection signs of arcing on a dry joint on a relay leg there noted and repaired, along with a number of other suspects.  Reinstalled and it is still working... well two months at this stage.

3# This is now in storage, with my growing collection of other spare and replaced parts.
 

Offline Simon

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Re: How long should electronics last
« Reply #28 on: December 25, 2017, 01:23:21 am »
Well this one is well made, like i say it still worked but for a small failure whos cause it not traceable to any assembly issues but is enough to put the kibosh on the whole thing. for £190 they are probably not worth repairing. The only thing I can think of is a filter ceramic capacitor in the thermistor input could have shorted internally but somehow I doubt it.
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Offline grumpydoc

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Re: How long should electronics last
« Reply #29 on: December 25, 2017, 01:35:39 am »
Indeed. My board has not seen high temperatures. I don't know what uC they are using but really can you deliberately make such poor quality chips on purpose?
Probably not temperature per se but temperature cycling can kill things relatively quickly.
 

Offline Monkeh

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Re: How long should electronics last
« Reply #30 on: December 25, 2017, 01:40:22 am »
I am used to designing stuff to be indestructible and last forever.

The only thing I can think of

These two statements don't add up. You're used to designing stuff to last but you can't think of failure modes?!

Open pull-up resistor.
Shorted ceramic cap.
Open ceramic cap.
Silver leeching causing termination failure of SMD caps or resistors (potential cause of above opens).
Fractured via.
Fractured solder joint.

Just a few random thoughts. We'll ignore the 'good looking' electrolytics, and the assumption there's no additional circuitry in the thermistor input.

Oh, and it's also possible at some point in the last 9 years of services and repairs someone has given the chip a nice belt and the damage is finally apparent.
 

Offline danadak

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Re: How long should electronics last
« Reply #31 on: December 25, 2017, 01:53:54 am »
There is extensive literature on long term reliability integrated circuits
on the web, just google "long term reliability integrated circuits", tons
of hits.


Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 

Offline chris_leyson

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Re: How long should electronics last
« Reply #32 on: December 25, 2017, 01:57:25 am »
Glad you got it fixed Simon,
Quote
Well I'm not a conspiracy theorist but sometimes I wonder at how fast stuff breaks down when I am used to designing stuff to be indestructible and last forever
I think a lot of engineers would rather over engineer things to make them last but there comes a point where you have to stop especially if the engineers are working to tight budgets or timescales. If your product is connected to mains 24/7 you've got to test for brown outs, surges, fast triansients and more, then there are all the what if questions, if a component goes open or short will it fail safe and sometimes small details might get overlooked. I think the Seiki 39" TV with the impressively bad PSU failure is one example where profit was more important than safety and reliability, maybe they just copied bits and pieces from other designs without putting any real engineering effort into the design. On the other hand I still have a DAC90A that is well over 50 years old and it just needs a re-cap, after all paper caps weren't designed for a 50 year life span.
 

Offline tecman

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Re: How long should electronics last
« Reply #33 on: December 25, 2017, 02:35:49 am »
One thing not mentioned are tin whiskers.  They are a common cause of "failure" that is a gift of lead-free solder mandates.  They can cause shorts between pins resulting in a bad input or signal, up to a large short circuit.  Many in the industry are not aware of the issue, but it has been around for decades.  I was exposed to it years ago designing some mil hardware.  All hi-rel mil and space equipment still use lead based solder for that reason.  Sometimes you can see the whiskers under a microscope and try to remove them, but often it is looking literally for a needle in a haystack.  One repair mitigation is to flux and reheat (reflow) the unit.  The whiskers will pull back into the joints.

As I said many "failures" are caused by diagnosed whishers.

https://nepp.nasa.gov/WHISKER/background/index.htm

Paul
 
 

Offline chris_leyson

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Re: How long should electronics last
« Reply #34 on: December 25, 2017, 03:26:12 am »
I've only even seen one tin whisker, it had been happily growing inside a hermetically sealed relay, once the top of the relay was filed off you could see it with the naked eye if the illumination was just right so it must have been quite big by tin whisker standards. From what I've read pure tin plating is the most likely cause of tin whiskers and not lead free solder, http://www.indium.com/blog/pb-free-solders-are-not-the-cause-of-tin-whiskers.php
I think in the case of the relay you've got stamped and formed tin plated parts which have residual mechanical stress and lead free solder just adds to the stress, the whisker wasn't growing out of a solder joint.
« Last Edit: December 25, 2017, 03:37:10 am by chris_leyson »
 

Offline james_s

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Re: How long should electronics last
« Reply #35 on: December 25, 2017, 03:52:53 am »
Sometimes stuff does just fail for no readily apparent reason. Several years ago I fixed a Bosch dishwasher with an unusual fault, the "fix" was adding an external pullup resistor to one of the IO pins on the microcontroller and today it still works just fine. I know of several other identical dishwashers that have not had any electronic faults at all so I'm not inclined to believe that it was the result of a design flaw. Failure analysis is a complex topic, there are so many factors that come into play.
 

Offline Simon

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Re: How long should electronics last
« Reply #36 on: December 25, 2017, 04:13:35 am »
I am used to designing stuff to be indestructible and last forever.

The only thing I can think of

These two statements don't add up. You're used to designing stuff to last but you can't think of failure modes?!

Open pull-up resistor.
Shorted ceramic cap.
Open ceramic cap.
Silver leeching causing termination failure of SMD caps or resistors (potential cause of above opens).
Fractured via.
Fractured solder joint.

Just a few random thoughts. We'll ignore the 'good looking' electrolytics, and the assumption there's no additional circuitry in the thermistor input.

Oh, and it's also possible at some point in the last 9 years of services and repairs someone has given the chip a nice belt and the damage is finally apparent.

As i've repeatedly said this board is in excellent condition, it has not been overheated or thermically cycled for that matter as most of it's life has been spent in a room so it has seen nore more than 40C and no less than 0C, not really what you would call thermal cycling.

I didn't design this board so I don't know what mitigation went into it's design. What is more astounding is not what if the electrolytic capacitor 20mm away that may have little to do with the uC has fasiled but there is no sign of bypass capacitors at all unless i am to count one of the small (maybe 0.1uF) ceramics. I've not tried to reverse engineer it. As I've also said it is strange that this one input has failed yet several others are obviously working fine, I'll have to get my meter and test the ceramics, maybe one is shorted internally but for that the only other failure mode i can think of is the uC failing which.... now that I have removed the firmware label from it i can tell you is an ST72C216G1B so not some won-hung-lo thing.
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Offline Simon

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Re: How long should electronics last
« Reply #37 on: December 25, 2017, 04:14:08 am »
oh and the cap is rated for 105C
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Offline Simon

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Re: How long should electronics last
« Reply #38 on: December 25, 2017, 04:15:22 am »
And there are movs on the mains input.
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Offline Zero999

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Re: How long should electronics last
« Reply #39 on: December 25, 2017, 05:23:48 am »

Now when you say boiler, you mean for heating your home, not hot tap water right?
I know that the hot water tanks have a microscopic thin layer of glass coating in them which supposed to last only 10 years.  After that time, as the glass thins out, and the water reaches metal, the metal eventually begins to rust and your water goes brown.  My last hot water tank began browning after 16 years of use and I switched it quick before either my tank ruptured, or, too much metal rust would permanently damage my piping and faucets.  If a heater boiler has a similar glass coating, it may have a similar lifetime expectancy, or, at least check with the manufacturer and they will tell you the life time of the tank.

This is a gas combi boiler, it heats both radiators for heating and hot water instantly for domestic use. The controller board looks brand new, like i say a thermistor would go straight to the uC so if it's saying that the fault is there then it must be the uC itself, one of the hardiest components surely?
Hot water tanks for domestic use have the glass lining, otherwise the hot water will begin to taste funny after 2 years or so...  You may stretch your tank to around 15 years if you fix your controller board, however, it is recommended in the industry to swap tanks every 9-10 years.  I never kept my hot water tank boiling steaming hot, so the heat from the gas burner below the tank didn't erode away the glass lining too fast (thermal stress) and I managed a 16 years.  I guess if you are in a more mild climate compared to here in Montreal, you may get away with 20 years...
That sounds like a very odd set up to me. I don't have a hot water tank at my house, but my parent's do. The tank is made from copper and is situated in an upstairs cupboard, over 5 metres away from the boiler. The water in the tank never mixes with the tap water. Water circulates from the boiler, through a coiled pipe, inside the tank, which acts as a heat exchanger. The tank does have a heating element (immersion heater), which can be used in case the boiler or gas supply fails.
 

Offline Monkeh

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Re: How long should electronics last
« Reply #40 on: December 25, 2017, 05:24:59 am »

Now when you say boiler, you mean for heating your home, not hot tap water right?
I know that the hot water tanks have a microscopic thin layer of glass coating in them which supposed to last only 10 years.  After that time, as the glass thins out, and the water reaches metal, the metal eventually begins to rust and your water goes brown.  My last hot water tank began browning after 16 years of use and I switched it quick before either my tank ruptured, or, too much metal rust would permanently damage my piping and faucets.  If a heater boiler has a similar glass coating, it may have a similar lifetime expectancy, or, at least check with the manufacturer and they will tell you the life time of the tank.

This is a gas combi boiler, it heats both radiators for heating and hot water instantly for domestic use. The controller board looks brand new, like i say a thermistor would go straight to the uC so if it's saying that the fault is there then it must be the uC itself, one of the hardiest components surely?
Hot water tanks for domestic use have the glass lining, otherwise the hot water will begin to taste funny after 2 years or so...  You may stretch your tank to around 15 years if you fix your controller board, however, it is recommended in the industry to swap tanks every 9-10 years.  I never kept my hot water tank boiling steaming hot, so the heat from the gas burner below the tank didn't erode away the glass lining too fast (thermal stress) and I managed a 16 years.  I guess if you are in a more mild climate compared to here in Montreal, you may get away with 20 years...
That sounds like a very odd set up to me. I don't have a hot water tank at my house, but my parent's do. The tank is made from copper and is situated in an upstairs cupboard, over 5 metres away from the boiler. The water in the tank never mixes with the tap water. Water circulates from the boiler, through a coiled pipe, inside the tank, which acts as a heat exchanger. The tank does have a heating element (immersion heater), which can be used in case the boiler or gas supply fails.

US/Canada. Odd is normal.
 

Offline Cerebus

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Re: How long should electronics last
« Reply #41 on: December 25, 2017, 06:07:50 am »
That sounds like a very odd set up to me. I don't have a hot water tank at my house, but my parent's do. The tank is made from copper and is situated in an upstairs cupboard, over 5 metres away from the boiler. The water in the tank never mixes with the tap water. Water circulates from the boiler, through a coiled pipe, inside the tank, which acts as a heat exchanger. The tank does have a heating element (immersion heater), which can be used in case the boiler or gas supply fails.

US/Canada. Odd is normal.

Forty years ago a hot water tank was the norm in UK houses and flats. The switch to combi boilers started en-masse in the 80s for new build and replacement of existing boilers.
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Offline Simon

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Re: How long should electronics last
« Reply #42 on: December 25, 2017, 06:10:55 am »
my dad still has a tank because the wankers that did his free boiler replacement simply replaced the old boiler with a newer design that is more efficient (along with fucking up everything they could in the process and then dissapering). with the old "boilers" they were so inefficient that in the summer i found it would be cheaper to use the electric element and permanently turn off the pilot light for the gas.
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Offline Gyro

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Re: How long should electronics last
« Reply #43 on: December 25, 2017, 06:12:32 am »
There are still a lot of us with the benefit of having the remains of a tank of hot water when the boiler goes out. I've no intention of changing - the water is far too hard around here!
Chris

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Offline Zero999

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Re: How long should electronics last
« Reply #44 on: December 25, 2017, 06:21:20 am »
Now when you say boiler, you mean for heating your home, not hot tap water right?
I know that the hot water tanks have a microscopic thin layer of glass coating in them which supposed to last only 10 years.  After that time, as the glass thins out, and the water reaches metal, the metal eventually begins to rust and your water goes brown.  My last hot water tank began browning after 16 years of use and I switched it quick before either my tank ruptured, or, too much metal rust would permanently damage my piping and faucets.  If a heater boiler has a similar glass coating, it may have a similar lifetime expectancy, or, at least check with the manufacturer and they will tell you the life time of the tank.

This is a gas combi boiler, it heats both radiators for heating and hot water instantly for domestic use. The controller board looks brand new, like i say a thermistor would go straight to the uC so if it's saying that the fault is there then it must be the uC itself, one of the hardiest components surely?
Hot water tanks for domestic use have the glass lining, otherwise the hot water will begin to taste funny after 2 years or so...  You may stretch your tank to around 15 years if you fix your controller board, however, it is recommended in the industry to swap tanks every 9-10 years.  I never kept my hot water tank boiling steaming hot, so the heat from the gas burner below the tank didn't erode away the glass lining too fast (thermal stress) and I managed a 16 years.  I guess if you are in a more mild climate compared to here in Montreal, you may get away with 20 years...
That sounds like a very odd set up to me. I don't have a hot water tank at my house, but my parent's do. The tank is made from copper and is situated in an upstairs cupboard, over 5 metres away from the boiler. The water in the tank never mixes with the tap water. Water circulates from the boiler, through a coiled pipe, inside the tank, which acts as a heat exchanger. The tank does have a heating element (immersion heater), which can be used in case the boiler or gas supply fails.

US/Canada. Odd is normal.

Forty years ago a hot water tank was the norm in UK houses and flats. The switch to combi boilers started en-masse in the 80s for new build and replacement of existing boilers.
I didn't say having a water tank was odd. Read Brian's post I was responding to, which you removed. It's odd to have a steel hot water, which is heated directly by a gas flame. I've never seen that before!
 

Offline Rick Law

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Re: How long should electronics last
« Reply #45 on: December 25, 2017, 07:26:24 am »
Sometimes stuff does just fail for no readily apparent reason. Several years ago I fixed a Bosch dishwasher with an unusual fault, the "fix" was adding an external pullup resistor to one of the IO pins on the microcontroller and today it still works just fine. I know of several other identical dishwashers that have not had any electronic faults at all so I'm not inclined to believe that it was the result of a design flaw. Failure analysis is a complex topic, there are so many factors that come into play.

I know you did not say it is a design flaw in the quote - I quoted it because it makes one think about the term "design flaw" - that "it is a design flaw" or not is really a matter of the requirement.

If you are tasked with designing (for example) a water heater to last 10 years, your design based on analysis would last 20 years.  The result then is not the product requested.  Presumably, cost can be brought down by reducing the life expectancy.  If the customer had wanted it to last 20 years, they would have brought the 20 years model.

Similarly, if one is tasked to design a DMM with +-2%.  It would be a waste to spend the extra for 0.1% parts if the model is only rated for +-1%.  Of course with exception where it is necessary to have 0.1% parts there to achieve the +-1% end goal.  By sourcing lower cost parts, they can afford to make this model cheaper if the source cheaper parts.

Even in cases where you know re-doing the layout of that area of the PCB would increase durability, you need to put into consideration that the durability is worth the investment to re-do by both the manufacturer and the end user.  Lower cost with lower durability and/or lower quality do have its place in the market.

So I am not sure if it is correct to interpret it as a design flaw or meeting designed criteria unless the design criteria is known.
 

Offline Simon

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Re: How long should electronics last
« Reply #46 on: December 25, 2017, 08:13:13 am »
To be honest my initial point was about the actual life span of parts, the silicon devices and basic passives like resistors and capacitors. It's not like this thing has seen vibration or heat and seems reasonably designed.
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Offline Cerebus

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Re: How long should electronics last
« Reply #47 on: December 25, 2017, 08:29:34 am »
Now when you say boiler, you mean for heating your home, not hot tap water right?
I know that the hot water tanks have a microscopic thin layer of glass coating in them which supposed to last only 10 years.  After that time, as the glass thins out, and the water reaches metal, the metal eventually begins to rust and your water goes brown.  My last hot water tank began browning after 16 years of use and I switched it quick before either my tank ruptured, or, too much metal rust would permanently damage my piping and faucets.  If a heater boiler has a similar glass coating, it may have a similar lifetime expectancy, or, at least check with the manufacturer and they will tell you the life time of the tank.

This is a gas combi boiler, it heats both radiators for heating and hot water instantly for domestic use. The controller board looks brand new, like i say a thermistor would go straight to the uC so if it's saying that the fault is there then it must be the uC itself, one of the hardiest components surely?
Hot water tanks for domestic use have the glass lining, otherwise the hot water will begin to taste funny after 2 years or so...  You may stretch your tank to around 15 years if you fix your controller board, however, it is recommended in the industry to swap tanks every 9-10 years.  I never kept my hot water tank boiling steaming hot, so the heat from the gas burner below the tank didn't erode away the glass lining too fast (thermal stress) and I managed a 16 years.  I guess if you are in a more mild climate compared to here in Montreal, you may get away with 20 years...
That sounds like a very odd set up to me. I don't have a hot water tank at my house, but my parent's do. The tank is made from copper and is situated in an upstairs cupboard, over 5 metres away from the boiler. The water in the tank never mixes with the tap water. Water circulates from the boiler, through a coiled pipe, inside the tank, which acts as a heat exchanger. The tank does have a heating element (immersion heater), which can be used in case the boiler or gas supply fails.

US/Canada. Odd is normal.

Forty years ago a hot water tank was the norm in UK houses and flats. The switch to combi boilers started en-masse in the 80s for new build and replacement of existing boilers.
I didn't say having a water tank was odd. Read Brian's post I was responding to, which you removed. It's odd to have a steel hot water, which is heated directly by a gas flame. I've never seen that before!

I didn't say that you said that it was odd.

I didn't even say that anything anybody said was odd.

I did think that several people about here are a little odd, but I didn't say it.

Removing seventeen layers of posts is just a simple courtesy to people who don't want to have to wade past 50 lines of text to read my one or two liner, not an attempt to cunningly conceal what you really said, so that I can entrap you into appearing odd, or an odd-sayer, or even to reveal you as the secret seasonal turkey snacker that we all suspect you to be.  :)
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Offline tpowell1830

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Re: How long should electronics last
« Reply #48 on: December 25, 2017, 08:46:30 am »
Indeed. My board has not seen high temperatures. I don't know what uC they are using but really can you deliberately make such poor quality chips on purpose?

In a perfect world, where handling and installing uC on the PCB is done with perfect precision and care, the uC would live very, very long. However, there could have been a micro-fracture undetected in the silicon of this single chip and installed and constant cycling and stress from handling and installation could have made it worse. Even though the PCB was not in a very hot environment, as you say, the PCB has some movement and heat fluctuations over time and this could have further stressed the chip until finally it did not function.

Also, as you pointed out, the capacitors look new and clean, however, I have seen very clean and new looking caps have very low ESR over time, which diminishes the filtering ability. Also, over time, the capacitance diminishes, therefore diminishing the filtering ability. The uC has a tolerance that allows voltage pops and the caps provide this protection, until it doesn't and the uC can take no more and breaks.

There are 10s if not hundreds of other scenarios in which this uC could have failed, mostly related to handling, electrical, installation and environmental stress conditions.

When you think of all of the conditions in which you have a perfect PCB, the probability of meeting all of the perfect conditions is so astronomically large that the devices will not eventually fail that it is what I would call a success that you got 9 years of service from this system.

Just my 2 cents...
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Offline SparkyFX

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Re: How long should electronics last
« Reply #49 on: December 26, 2017, 05:52:56 am »
If your product is connected to mains 24/7 you've got to test for brown outs, surges, fast triansients and more,[...]
... which are hard to be predicted or quantized. I mean, ten years ago i rushed to disconnect the devices when there was a thunder and lightning nearby. Very few things broke (maybe a power brick), but the chance of devices breaking is higher with more devices connected to mains. Does that statistic outrun the allegedly less resilient devices or the use of microelectronics?

Especially transient protection is neither perfect nor completely reliable, apart from expectations regarding surge protectors. Of course, after the last failed attempt at washing machine repair, i better put an extra surge protector in front of it, just to increase chances. Those LNK304 DC/DC converters seem to violently loose their chip package right often in Whirlpool devices, people on ebay specialized in sending the repair kits/spare parts in envelopes.
« Last Edit: December 26, 2017, 06:34:07 am by SparkyFX »
 


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