Electrical and Electronics Recovery After Disasters

[rdocr]

( I entered this here, knowing that TPTB will move it if they see fit.)

We have become a throw-away culture and it is time to change. Earlier generations repaired or patched anything.

I still chuckle about 850,000 cell phones dropped in the toilet in a year in U.K. ( from a past Blog), but there are other incidents where electric motors and electronics get wet or contaminated. The party is not over for them if you are patient.
   Spill coffee on a computer keyboard?
   Leave a motor driven appliance outside to get rained on?
   Subject any electrical or electronic device to extreme cold?
   Any disaster-related exposures: dust from earthquakes, flood waters, smoke from fires, dust storms, etc.

If you try the thing after any of the above, it will either overheat in a few minutes and fail, or it simply will not work. Here are some revival techniques that work MOST of the time.

Drying
Insulation fails if it is wet. The device will overheat and fail after a few minutes. The trick is to dry it out. A motor takes about a week at around 150F, to become thoroughly dry.. It can be tested beforehand with a Megohm meter, meter (winding lead to steel frame containing the windings) and monitor this during the week to get it back to 50 megohms or better.
Or just cook it a week and try it. I have done this many times when I was repairing motors.

Oh, after the baking, the shaft requires new lubrication before trying.

If the immersion was for quite a while, rust may build up between the rotor and stator. Remove the rotor and polish these surfaces with sand paper ( NOT steel wool.).

Transformers require the same drying treatment. Longer drying with longer immersion.

Electronics and printed circuit boards.
   Water, especially flood waters, will leave dirt deposits between conductors on a printed circuit boards. Thoroughly wash the board with distilled water and dry it at 100F. Higher temps will likely damage integrated chips. You cannot use the Megohm meter on these boards.

               After drying, energize the device for a few minutes and see if it smokes or even smells. If not, energize it a little longer and try it again, each time giving it a longer period turned on.
I have revived  TV sets that were fished from flood waters as they floated by. They worked for years after revival.

The worst case is spilling lemon aide on a keyboard. The acid etches printed circuit boards beyond repair.

Washing also works after smoke exposure from a fire, or after dust and plaster powder after and earthquake.

As to cell phones dropped in the toilet, remove the battery and wash the phone out with distilled water, then let it dry at 100F or less for at least a week. If the urine didn’t stay in there too long, it should work. You might want to wipe it with toilet paper when first retrieved  :=))

Extreme cold exposure causes condensation within motors and electronics and both require the drying out processes described.

This is from our Disaster Preparedness books- they also cover recovery.

LOL,
Ralph

[jock]

Useful info, make and mend doesn't just apply to sewing stitching, carpentry etc but can be applied to more hi tech equipment. Cae in point. my home computer system and assosicated network is the envy of a number ogf geek friends and everything is salvaged, had a dab of solder or scavenged from clearouts.

[bhowle]

Living in a rural area without a good computer store nearby, I use our local recycling center as my parts store for optical drives power cords, NIC cards an the like.  Unless I can find fresh kill the stuff has been rained on, but usually works well after it's dried out.
Last week I got a D-link wireless card for free. This saves on a trip to the big city too.

-bob

[Doc Savage]

As to cell phones dropped in the toilet, remove the battery and wash the phone out with distilled water, then let it dry at 100F or less for at least a week. If the urine didn’t stay in there too long, it should work. You might want to wipe it with toilet paper when first retrieved  :=))

NEVER wash a cellphone, you will only make it worse. Dry it out as best you can, unscrew and open up, brush away any damage with isopropanol and blow it away with compressed air.

[rdocr]

As to cell phones dropped in the toilet, remove the battery and wash the phone out with distilled water, then let it dry at 100F or less for at least a week. If the urine didn’t stay in there too long, it should work. You might want to wipe it with toilet paper when first retrieved  :=))

NEVER wash a cell phone, you will only make it worse. Dry it out as best you can, unscrew and open up, brush away any damage with isopropanol and blow it away with compressed air.

Sorry, but I must disagree with you. The alcohol evaporates too rapidly and does not leave time to carry off any residue. Water does a better job of removing particles.
If you can imagine a toilet full of crap, the only hope is to get whatever is on or in a cell phone away from there ASAP.

Of course, the entire process is a gamble that the thing will work again, but its worth a try. TV's I have salvaged, but I have yet to recover a cell phone-

Frankly, I try to keep the bathroom as the only place in the house that cannot be reached by phone. I can't imagine doing any good in there with a phone ringing.

Ralph

[Doc Savage]

As to cell phones dropped in the toilet, remove the battery and wash the phone out with distilled water, then let it dry at 100F or less for at least a week. If the urine didn’t stay in there too long, it should work. You might want to wipe it with toilet paper when first retrieved  :=))

NEVER wash a cell phone, you will only make it worse. Dry it out as best you can, unscrew and open up, brush away any damage with isopropanol and blow it away with compressed air.

Sorry, but I must disagree with you. The alcohol evaporates too rapidly and does not leave time to carry off any residue. Water does a better job of removing particles.
If you can imagine a toilet full of crap, the only hope is to get whatever is on or in a cell phone away from there ASAP.

Of course, the entire process is a gamble that the thing will work again, but its worth a try. TV's I have salvaged, but I have yet to recover a cell phone-

Frankly, I try to keep the bathroom as the only place in the house that cannot be reached by phone. I can't imagine doing any good in there with a phone ringing.

Ralph

My job is repairing Nokia phones, been doing it for 5 years now and this is my experience with water damaged phones. More water won't help, wetting a stiff brush with isopropanol will work but as you say it's a gamble, the components are small and if badly corroded they can break of, damage under circuits can't be reached.
Using water to clean CRT TVs can work, the components are bigger, integrated circuits just cant handle water.
But in a post peak oil world cell phones won't be our concern, people with enough resources and free time to clean their underwear will be. 

[greenmom]

Great post, Doc! Thank you for the information.

(The best cell phone we ever had was a Nokia phone.  That thing was nearly indestructible.)

[TechGuy]

The biggest long term problem for electronics is electrolytic caps that dry out with age. As these electrolyte evaporates over time, the capacitance drops and the ESR (Equivalent Series Resistance) increases. Many electronics die because of electrolytic cap failure.

Another potential problem are with Rohs compliant electronics that have removed the lead from electronic solder to make them more green the problem is that lead is added to electronic solder to prevent the growth of Tin whiskers. Metals coated with Tin form microscoping whiskers that can create unintented electrical connectors causing the device to fail. It usually takes years for whiskers to form, and Rohs compliant boards are intented to only last a few years since virtually everyone upgrades there electronics every few years. Post collapse this presents a problem trying to extend the life of old electronics.

Recommend tools for post collapse electronics repair:
Electric soldering iron with temperature control and a several pencil point heads
Hot Air soldering rework. This devices produces a flow of hot air that can melt all pins on a high pin count chip at the same time.
Digital Multi-meter with VDC, VAC, Current measurement, diode testing, basic Inductance and and capacitance measurements
LCR meter capable of measuring Cap ESR, and leakage. Inductance Ringing
Cap regenerator, This device can be used to restore the oxide layer in caps that have sit idle for a long time with out use. This is a simple device that applies a low current voltage to the cap. The voltage is slowly increased over several hours until the voltage reaches the capacitors voltage rating.
Oscilloscope to check a circuit to see if whats working and whats not working. A Dual trace or better Oscilloscope with at least 100 Mhz of bandwidth.
A PCB board vise (aka panavise) that holds PCB's will you solder unsolder.
A BJT, SCR, MOSFET transistor testor to determine if a transistor is working.
Wirewrap wire. This is typically insulated 30 gauge wire that can be used to repair broken traces on PCBs by solder the ends of the wire to the two connection points. Sometimes when removing damaged parts the trace pads will break off. You can use the wirewrap wire to rejoin the broken trace at either the other end of the trace or at a via point. A bit of hot melt glue can be used to secure the wire to the pcb.
Fine gauge solder for resoldering surface mount replacement parts.
A set of long but fine pitch tweezers for positing small parts on PCBs.

[Zac]

Another potential problem are with Rohs compliant electronics that have removed the lead from electronic solder to make them more green the problem is that lead is added to electronic solder to prevent the growth of Tin whiskers. Metals coated with Tin form microscoping whiskers that can create unintented electrical connectors causing the device to fail. It usually takes years for whiskers to form, and Rohs compliant boards are intented to only last a few years since virtually everyone upgrades there electronics every few years. Post collapse this presents a problem trying to extend the life of old electronics.

The removal of lead from electronic solder for environmental reasons did cause some problems initially, but the problem has been addressed and nearly all major manufacturers have made changes to their processes to take care of this problem.  Also, low voltage equipment is less likely to form tin whiskers than higher voltage equipment. 

For electronics repair purposes, there's little reason to use lead free solder though. 

http://docs.google.com/viewer?a=v&q=cache:l5GA-gaiom4J:cdn.vicorpower.com/documents/industry_articles/rohs_article2.pdf+rohs+tin+whiskers&hl=en&gl=us&pid=bl&srcid=ADGEESgnzpbVs9HCVsbI87AJ32BvhVuVc-slBOupGd3eCY8prlAHUYe-G1N_X66exiMm-wFDAY1qZ4qv0zGHN3yTBI5VKyHH8CrHLCBGcbo75RRZhCv0yhl31iowcplcDLypoxczcm7T&sig=AHIEtbRy-qY-Levks3sqyGuUZpfVPBNAcg

[rdocr]

AMAZING
I never imagined the amount and variety of good information that would result from the original post. It is good to see the responses.
Alas, my methods were valid in their time, but they have obviously been replaced. My efforts to repair a faulty component have mostly been unsuccessful.

I don't quite see how applying a repolarizing voltage could solve the aging problem of lost moisture in an electrolytic capacitor, though.

A story:
I was faced with a tuner that had orange juice spilled over it. Every place that got a drop of juice had been etched clean- simnply bare. I kept the circuit board for a while as an example,  but I never even considered repair.

I hope the rest of you viewers who only use electronics will heed those with experience- I will.

Ralph

[TechGuy]

I don't quite see how applying a repolarizing voltage could solve the aging problem of lost moisture in an electrolytic capacitor, though.

A electrolytic cap sitting on a shelf with sufficient electrolyte will lose its thin oxide layer. Regenerating it will restore the oxide layer. If too much electrolyte is lost than regenerating the oxide layer would indeed be pointless.