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classic87

Experienced Member
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Oct 12, 2024
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Why do some electronic devices that were working stop working if they remain unpowered for long periods? Is there an explanation for this and is it possible to avoid it?
 
What type of device? For many devices with batteries, the battery needs to have some charge in order to accept additional charge and operate. Just check the device monthly and recharge as needed and the device will continue to operate for a long time.
 
Also, capacitors go bad just sitting there.
And sometimes early VC equipment with early CMOS chips and improper grounding can get zapped by pulling off a cloth dustcover.
I have a quarterly 'VC cycle' where I dedicate one weekend to just going around and testing each system, and let it run for 30 mins or so.
Monthly would be better, but don't have the time for it.

-J
 
consoles (snes, ps2 slim) tv crt 29", handheld consoles (without battery), tvboxes, drive dvd sata, iems in-ears headphones
 
It relates to component failure modes. A number of them happen inside transistors and integrated circuits, which are totally independent of the device being powered or not. So if you leave some apparatus for along time those failure modes still happen (could have happened 5 minutes after you last turned the thing off) then you switch it on a year later and make the false assumption it failed because it was turned off for a long time.

In terms of other common causes, electrolytic capacitors can lose form and become electrically leaky over years. That can do things like increase power up surge currents and take out components in the power supply when powered up again. One of the common problems is leaked electrolyte, when it initially leaks out, it is relatively non electrically conductive, but as it reacts with copper, Lead and Tin on the pcb it becomes Alkaline and highly electrically conductive. This can totally disable high resistance circuitry, corrode through components and pcb tracks too. To give you example of this sort of thing, here is a story about one of my precious 2465B oscilloscopes that was working fine when I put it away and 12 months later it would not power up, its PSU start up circuitry had become completely disabled:




In battery powered appliances, leaked electrolyte from batteries left in, especially alkaline cells, is equally as destructive to both components and pcb's and you also probably would have seen photos of batteries that have leaked onto computer motherboards.
 
I have four Foundry switches. One is powered on, the other three are spares.

When I recently powered up the other three, the power supplies popped after a few hours.

All three of them.

I suspect it's capacitor related but the PSUs are tight and extremely complex. Multiple daughterboards with control circuitry. It's a pity.
 
wrm said:
I suspect it's capacitor related but the PSUs are tight and extremely complex. Multiple daughterboards with control circuitry. It's a pity.
Click to expand...

Almost certain the capacitors failed.

Any time you start a device that has been sitting a long time:
Power up for a minute. Power off for an hour.
Power up for 5 minuets. Power off for an hour.
Keep adding 5 minuets to the power up time until you get to an hour at which point it is probably safe to let it stay powered up.

This procedure gives the capacitors a chance to reform without heating up to much and venting which destroys them.
Note that if the vent fails they can explode throwing shrapnel and chemical around. Wear protective equipment if they are exposed.
 
Semiconductors consist of pure silicon that is doped to produce the PN junctions.

Over time (and with increasing temperature) these dopants can migrate, thus changing the characteristics of the component itself.

Electrostatic discharge (due to handling) is another factor.

The device itself should be in a 'sterile' condition. However, the encapsulation itself can leak, thus letting in contaminants. Also, internal materials (such as epoxy resin) can also break down to form by-products that can contaminate the delicate silicon.

Search for 'Jedec semiconductor failure modes' to find out more. The Jedec website charges for reports. However, quite a few 'free' reports have been published.

Search for 'purple plague' as an in-built failure mode of a gold bond wire to an aluminium pad...

Dave
 
What is the maximum interval that I can store these electronics with minimum risk of failure?
 
classic87 said:
What is the maximum interval that I can store these electronics with minimum risk of failure?
Click to expand...

That depends on the composition of all of the electronic parts within the apparatus, who made them (multiple manufacturers Worldwide) and the MTBF of every individual part in the assembly and whether the person who was running late on a Friday afternoon completed the soldering correctly. For that, you will never acquire accurate data I'm afraid, you may as well go to a Greyhound track and bet on the Dog that has the most attractive fur coat.

But at a more pragmatic level, you could check out your apparatus every 6 months. If you detect a failure, track down the cause and repair it.
 
classic87 said:
What is the maximum interval that I can store these electronics with minimum risk of failure?
Click to expand...
How long is a piece of string...

I have bought devices that were encapsulated from silicon wafers from the 1980's that were stored in a clean room environment in nitrogen.

I belive I have had a couple of part failures across 350 boards (700 parts).

These were complex parts.

There are Standards for storing parts. The length of time is dependent upon the storage conditions - but even this is statistical (of course).

Dave
 
I was thinking of a separate electronic component - but (if we are talking of sub-assemblies or assemblies)...

We should also include (E)(P)ROM bit-rot and fuse regrowth on PAL logic where a fuse is 'blown'.

Dave
 
syzygy said:
View attachment 1301537
View attachment 1301538
Click to expand...
A number of IC's in storage foam did this because some of the early foams were Latex based and it contains Halides as a contaminant, that attacked the silver plating on the steel pins of the TI brand IC. Once the Silver plating fails, then the rust sets in. The silver plating also gets wiped out by atmospheric Hydrogen Sulphide (H2S), which in some places is very high level. Probably the worst place is Hell's Gate in Rotorua NZ.
 
Steve Toner said:
Tin Whiskers deserve an explicit mention as a potential failure mode as well.
Click to expand...
One interesting thing about Tin whisker faults, they can cause unique types of scenario where two circuits that are normally independent interact.

I had an LG brand computer VDU where suddenly it looked like a Ghost had operated the Menu buttons. At the same time, the screen contrast changed split right down the middle on the L & R sides. The main processor IC was fine pitch pin type and the board noted to be "Lead Free" on its markings and that should ring alarm bells too. It was caused by Tin whiskers between the pins of the processor IC. I have also had Tin whiskers affect one of my 2465B scopes and a number of vintage Germanium transistors too. I am not fond of them at all.

So if you see fault that appears absurd or inexplicable or counter intuitive based on a circuit's design, think Tin Whiskers, because they create entirely new circuit configurations that are not on the schematic.
 
Electronic devices have been on the market for several decades and to this day they have not been able to create a corrosion-resistant metal or protection on PCBs and components.
 
classic87 said:
Electronic devices have been on the market for several decades and to this day they have not been able to create a corrosion-resistant metal or protection on PCBs and components.
Click to expand...
It is impossible. Eventually, oxygen will eat everything. Gold plating has a long life span but even that is not immune.

The whisker problem was known and corrected decades ago. The solution was to have tin plus lead in the solder. Guess what happens when the laws require the removal of lead from solder.
 
And the zinc whiskers were produced when someone thought it was a good idea to zinc plate steel to make it less prone to corrosion.

Just swap one (known) problem for another (unknown problem) at the time...

Dave
 
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