App. Note 41 - Repair of Flood Damaged Equipment
Many pieces of electrical or electronic equipment can be repaired after
being immersed in flood waters. The basic work is not difficult, although
there will be components within the equipment which may not be repairable
except by experts, where, due to contamination by chemicals, pollutants,
or particulate matter, a refurbished component may not be safe. The former
is usually the case with hard-disc drives, and an example of the latter
might be the floppy disk drives-both used in computers.
These may be present from the moment the equipment is re-assembled
or they ma not show up until later. But in any event they may often be
of an intermittent nature and thus difficult to trace. Stabilants can
be used to prevent or solve these problems. We'll explain the use of this
material in some detail.
Most electronic equipment, including that used on cars, trucks, farm
machinery, communications, and in home entertainment can be successfully
repaired providing certain procedures are followed. When in doubt, contact
We'll begin with refurbishment of the more complex electronic equipment.
As you'll understand, many of the techniques relating to the electronics
will be similar in an event. While not all will be applicable to things
such as automobiles, etc., let's g over some of these steps
Metal components including electronic chassis and cases
Here the enemy is corrosion and exposure to air of water-soaked equipment
ca increase this problem. Often a consideration as to reparability is the
ease with which the electronics can be removed from their enclosures. Where
equipment housing contain accumulated silt, the use of warm water and detergent
might be needed t free-up the electronic components. Remember though that
the detergent will also remove any oily film from the metal parts which
could be protecting them again rusting. Therefore, it may be necessary
to spray the metal parts, housings, cases et with a good water-displacing
penetrating oil to protect them while the electronic components are being
Avoid the uses of oils containing silicones. While these could be effective
is displacement of moisture, they can cause problems with connectors and
could interfere with repainting any metal components.
General comments on cleaning circuit boards and connectors
Whenever detergent and water is used to clean circuit boards or connectors,
these should be rinsed off thoroughly such that no detergent residue is
left. Make sure that any card-edge connectors or other connectors are not
at the bottom of the board (where they will accumulate any material dissolved
in the rinse water). This is necessary as some detergents will leave a
hygroscopic (water-attractive) film on the surface of the circuit board
connector and if the film is too thick, can cause leakage currents at the
impedance's involved with some sensors. However, a small amount of anti-spotting
agent (itself a surfactant) can be added to the second-to-last rinse if
spotting is a problem.
Removal and cleaning of circuit boards
Disassembly can be somewhat tricky because of the potential for damage
of components by static electricity. Often silt will have penetrated under
ICs especially if they are socketed (as may be the case with microprocessors).
The use of running warm water and detergent (or surfactant) might be needed
to remove these deposits.
Obviously any plug-in boards will have to be removed from the mother-board.
It is advisable to make a note of the name (part # or serial #) for each
board as they are removed. What might seem obvious at the time may not
be so easy to remember later. This caution also applies to any wiring-harness
connectors in the system. Wires can be tagged using surgical tape until
such time as a listing can be made. A rough sketch of each connector location
can often save hours of work later on.
SIMM's should be removed from the mother-boards and here again,
be sure to note which board went where. In the case of ICs you must remember
that it may be difficult to pull an IC with a large number of pins-without
damaging it or the circuit board.
Boards should be dried, preferentially without use of high-pressure
air which may not only damage components, but which could drive particulate
contaminants into inaccessible locations. A hair dryer set on low heat
may be sufficient providing it is not directed at a heat-vulnerable component
at close range. Try to "ground-out" the circuit board by using one of the
conductive rubber mats. Avoid touching any component or circuit board trace
with any part of the dryer.
Wiring harnesses will often hold moisture and must be dried out before
being re-connected. Where, as in the case of computer power supplies, the
wiring may be soldered to a board it's rarely necessary to disconnect it.
Transformers and inductors
Both switching-mode and conventional power supplies may contain transformers.
Some transformers have windings which are not impregnated with a sealant
during manufacture. If you attempt to turn-on a power supply without first
drying this type of transformer, not only can they short-out, but an electric
shock hazard could be created in the event that there is an electrical
break-down between windings. Again, low heat, in the range of from 100
to 130'F, should work.
Electrolytic-type filter capacitors
Although electrolytic filter capacitors are metal cased, some have
a small vent which might admit moisture. Since this vent is necessary to
release any internal pressure which would occur in the case of an overload,
some of these capacitors employ sealing system designed only to prevent
a build-up of internal gas pressure an should, therefore, not admit moisture.
Often the only way to make sure that capacitor has survived immersion is
by testing, or by actually applying power to the supply. In this case,
be sure that you won't be exposed to flying debris in the eve that the
capacitor has shorted out internally, for it might rupture its cases explosively.
Don't attempt to replace a fuse that blows with a larger one. If
blows it is usually better to assume a capacitor has shorted-out.
While on the subject of power-supplies, remember that many switching-mode
power supplies contain cooling fans. These may be of the sealed-coil type;
removal of the rotor can usually be accomplished by the use of a Circlip
tool. If the fan doesn't turn freely, it may be packed with silt and require
Hard-disk drives as used on computers
This is a tough one. While the cases are "sealed" they are also vented,
usually through a small filter. Depending on the depth to which the hard-disk
drive was submerge the sealed cases could have become contaminated with
water or particulate material Your best bet is to contact the manufacturer
of the hard-disk drive to obtain the name of a reputable data-recovery
service. Follow their instructions as to packing an shipping to the letter
as improperly packed drives may damage the internal storage media!
The cost of these is such that you may be far better off replacing
them rather than risk damage to a disk because of residual contamination.
It only takes one bit of grit to ruin a floppy disk!
CD, CD-ROM and other optical drives
Contact the manufacturer or the manufacturer's service center.
Depending on the type of key-switches used, these may be repairable.
However the cost of a typical PC-clone keyboard is low enough that refurbishment
may not be worth the time involved. If in doubt, call the manufacturer.
If anyone attempts to use the keyboard, the must remember to wash their hands!
The reparability can be dependent upon the type of microphone and/or
handset used. if the rest of the phone can be refurbished, it might be
cheaper to replace the handset. REMEMBER that raw sewage may have come
in contact with the handset. For obvious reasons,
DO NOT place the handset to the face of the person who is attempting to
use the phone until it is disinfected
Typewriters, laser-type printers, and printers
In the case of most electric typewriters, the same procedure
can be followed as is used for re-conditioning of older typewriters. Remove
the case if possible. Remove any fuses, motors, print-heads, and circuit
boards. Remove any rubber drive belts, platens and rollers. If cog-type
timing-belts are present, mark their position with respect to the pulleys
so that they can be replaced in the identical position. Clean these parts
with warm water and a mild detergent, rinsing thoroughly. Clean the typewriter
of silt and crud using hot water and a good detergent. A small amount of
kerosene may be added to the wash water if grease, tar or oil contamination
is hard to remove. Use proprietary de-greasing sprays with great caution
as some of them are caustic agents which convert greases and oils to soap-like
materials. These materials can also cause damage. Rinse and re-oil any
mechanical mechanism using a penetrating oil (making sure that it does
not get on any pulleys). Clean out the motor using a solvent- type cleaner
such as isopropanol, using it in a well ventilated area. Let the motor
dry. Do not expose it to hot heating elements or open flame when drying.
Reassemble and test for mechanical hang-ups. Before re-connecting the drive
motor belt or gear linkage, check to sure that the motor runs properly.
Laser-type printers are much more difficult to repair. The order
in which they are disassembled is often quite important, and it is not
unusual to find that special jigs and fixtures must be used to insure proper
alignment of certain components. If you don't have these and don't have
a technical manual, we suggest you contact the manufacturer. Remember that
many of them use a silicon fluid in the unit to prevent the thermoplastic
ink from adhering to the pressure roller. This in itself, can cause connector
problems if it is not flushed-out properly by using alternating flushings
with kerosene and isopropanol.
Dot-matrix and daisy-wheel printers can be treated much the same
way as typewriters. In the case of the former, you may have to replace
Fluid-ink-jet printers. Obviously you'll throw away any ink cartridges.
After removal of any electrical components or circuit boards, clean the
mechanical components and re-oil as necessary. Replace the dried electrical
components and use a new set of cartridges. As before, when in doubt, call
Communications equipment, including avionics, CA TV, mobile, etc.
Stabilants have been used in the manufacture and maintenance
of these types of equipment for several years. Contact us if you have any
Electrical dispatch, switching and process control equipment
Again, Stabilants have been used for several years in the repair
and maintenance of this type of equipment.
Automobile, Truck and Farm Machinery electrical problems
We'll confine our suggestions to the electrical and electronic areas
of this equipment. Most of the problems will be related to either immediate
or delayed-action connector malfunctions, especially with equipment that
relies on computer-control modules connected, as they are, with numerous
sensors. On the assumption that any small sensor ports (to intake vacuum
and the like) are free of obstructions, that the wiring harness itself
is reasonably dry and that the engine, transmission, differential(s), steering
gear, brakes and wheel bearings are free of contamination and properly
lubricated, and that any control modules have not been damaged physically,
a systematic cleaning and treatment of the electrical and electronic connectors
may have to be done before problems can be considered to be the fault of
the control modules themselves.
In addition to the sensors, all electrical contacts on the wiring harness
should b treated; everything from head-light connectors, fuse holders,
dashboard connectors (such as for dashboard lights, gauges, etc.) to turn-signal
switches. (Remember switches can be subject to corrosion too). Screw terminals
too should be treated wit a drop of Stabilant 22A.
In fact most of the electrical-connection problems can be fixed or prevented
by using Stabilants.
Other types of equipment.
The Stabilants can also be used on connectors and switches in
home appliance such as on the "program" contacts on electric dishwaters,
washers and dryers. This applies to connectors in general, irrespective
of whether they are screw terminals, tab connectors or other types.
What is Stabilant 22?
Stabilant 22 is an initially non-conductive block polymer
which when used in a thin film between metal contacts becomes conductive
the effect of an electric field. This occurs at an electric field gradient
such that the material will remain non-conductive between adjacent
contacts in a multiple pin environment. In addition Stabilant 22 exhibits
surfactant action as well as lubrication ability providing a simple component
resident solution to virtually all contact problems.
When applied to electromechanical contacts, Stabilant 22 can provide
the connection reliability of a soldered joint without bonding the contact
Where can Stabilant 22 be used?
Stabilant 22 can be used in all types of connectors, at frequencies
from to DC t several Gigahertz, on faders or potentiometers, or in non-inductive
(non-arcing power-interrupt switches. The number of uses are almost limitless.
Is Stabilant 22 just another contact cleaner?
No, Stabilant 22 is a resident potentially electrically-active
which through synergistic combination of effects enhances conductivity
within a contact without causing leakage between adjacent contacts. Thus
large quantities of the material d not have to be "hosed" on as is the
case with cleaners.
Is Stabilant 22 cost effective?
As Stabilant 22 can be quickly applied to all contacts and connectors
in a system the often difficult diagnostic determination as to which one
of many contacts are erratic, can often be eliminated. This can significantly
reduce service time in the field and in many cases eliminates the need
to return boards for shop service or re-manufacturing. As any service manager
knows, the diagnosis of electronic problems especially where intermittent
failures are concerned, is often much more difficult than the actual part
replacement; as well as requiring service personnel of exception caliber.
In many cases the use of Stabilants can thus increase the efficient(
o existing staff as well as allowing many connector harness related problems
to be handled at a much lower cost.
How can Stabilants correct electrical contact problems?
In many electronic applications demodulation (detection) of RF signals
in connectors exhibiting thin-film rectification effects can either reduce
the signal-to-noise ratio or introduce artifacts which can disrupt data
flow. Stabilants can cure these.
While Stabilants have demonstrated that they can cut the cost
of both shop and field maintenance; their use in the manufacturing of electronic
systems can speed up production as well as reducing rejections.
How does Stabilant 22 work?
Contact failure is rarely caused by a single factor. Thus, treatments
that solve only one problem don't necessarily offer a reliable long term
solution. For example, cleaners do not prevent the re-entry of contaminants
or the reformation of contaminant films; nor do they offer any lubrication.
They must be used each time a connector gets dirty. Lubricants in themselves
are rarely cleaners. Corrosion inhibitors are neither cleaners nor lubricants
and are often specific to one type of metal or plating. Unsaturated oils
used as contact treatments can cross-link under the influence of elastomer
or thermoset plastic curing agents and accelerants.
While resident in the connector, Stabilant 22 performs several
concurrent functions. Its very presence in the contact gap will prevent
the entry of outside contaminants. It has sufficient surfactant action
to lift surface contaminants and hold them in suspension. In cases where
corrosion products are present Stabilant 22 will penetrate them
and prevent rectification effects. Due to its high dielectric constant
it will act to form a capacitative layer which is in parallel with whatever
residual resistance exists in the contact increasing the passage of AC
signals. Given sufficient DC bias within the gaps of the contact the thin
film of Stabilant will "switch", conducting by quantum tunneling
and thus limit the resistance of the contact to a serviceable level.
In what forms is Stabilant available?
The Stabilants are available in several forms; as a concentrate (Stabilant
22) and as an isopropyl alcohol-diluted form (Stabilant 22A).
In a similar fashion, we produce Stabilant 22E Because of the 4:1
dilution, a given size container of Stabilant 22A will cost about
one-fifth the amount of a container of Stabilant 22 as it contains
only one-fifth the amount of the concentrate.
What is the difference in use of these materials?
Stabilant 22 is most useful where the connections are out in
the open - such as card-edge connectors or where the lubricating properties
of the material are useful such as an aid to installing microprocessor
IC's or on switches. Where the connections are not too easy to get at or
where the user wishes to apply the material to something such as a socketed
IC (without removing the IC from its socket) it is easier to use the alcohol
diluted form (Stabilant 22A or Stabilant 22E). The isopropyl
alcohol diluant serves ONLY to carry the concentrate into the connector.
The Stabilants have proven to be very effective in improving
the reliability of connectors in general and are developing a reputation
for ease and speed of use under field conditions. Not only are many OEM's
pre-treating sensor connectors during manufacture, many are providing the
their service technicians either as Standard-Store items, or recommending
them for field procurement.
The Stabilants are presently used in applications ranging from
Avionics through Process control, including such critical fields as Bio-medical
electronics, Air-Traffic Control, Police & Emergencies (such as communications
and the like).
How are the Stabilants applied?
The application of the Stabilants is exceptionally easy. Just
use a drop of two o Stabilant 22A on one of the electrical or electronic
sensor connectors, including an other in-signal-path connector in the wiring
harness, and reconnect the system.
What packaging is available?
We can supply the concentrate (Stabilant 22) in 5 mL, 15mL,
5OmL, lOOmL, 250m 5OOmL and 1 Liter bottles. The dilute (Stabilant 22A)
available in 5OmL, 100m 25OmL and 5OOmL containers. We do not have a 1
liter container of the dilute as 500 mL is the largest size bottle that
can be shipped by air (in single or multiple packages) without additional
restrictions. We maintain our stock in depth, and ship most orders the
same day they are received. The 15 mL and 50 mL sizes are in dropper bottles
and these are available on request for the ) 0.5 mL sizes as well.
Is it available in a spray can?
No. Why waste the material? We would like to think we are environmentally
responsible and safety conscious. We use no CFCs, HCFCs or any other ODC
(Ozone Depleting Chemical) either in or in the manufacture of Stabilants.
In addition even Stabilant 22A has only about 1/200th the solvent
impact as conventional contact cleaning solvents over a three year time
span. As Stabilant 22 contains no solvent it has absolutely minimal environmental
impact and is, therefor becoming the treatment of choice for many service
Just how much should be used?
Normally, a final film thickness of from 0.5 mils to 1 mils of the
concentrate is all that is necessary. In other words, you want just enough
to fill up the interstices between the contact's faces. When using Stabilant
22A, use enough so that once the alcohol evaporates the desired 1/2
to 1 mil film of Stabilant 22 remains.
In applications to moving surfaces, such as in slip-rings or potentiometers,
film thickness should be minimized to the point where "hydroplaning" won't
What is the 15mL service kit?
This was made up at the request of several manufacturers who wanted
a standard kit that they could issue to their service personnel. It consists
of a 15mL dropper bottle of Stabilant 22A and some applicators,
all in a small capped cardboard tub that can be tossed into a tool box
Does the action of Stabilant deteriorate with age?
In some field trial applications lasting over ten years Stabilant
22 has shown no sign of reduced effectiveness. With a high molecular
weight and a very low vapor pressure, almost none of the material will
be lost by evaporation. Unlike some other contact protection oils, Stabilant
22 will not cross-link when exposed to free-machining materials such
as high-sulfur brass, or when used on contacts where agents used to promote
cross-linking of thermosets or elastomers are present in the environment
or in the actual connector components. Thus Stabilant 22 does not
form a scum or "varnish".
Quite frequently equipment that has been submerged
in flood waters will have become contaminated with fecal or other harmful
bacteria. A precautionary rinsing with isopropyl alcohol will generally
disinfect circuit boards from electronic equipment without damaging components
although semi-sealed items such as potentiometers may have to be replaced.
Isopropyl alcohol can also be used on metal parts and cases, although with
some finishes and paints a test should be made to make sure that the alcohol
won't damage the finish, In some instances, one of the home disinfectant
sprays may be used on the metal parts, but again, test for possible damage
to finished surfaces.
For the same reasons, precautions should be
taken when handling such equipment to avoid infection! And all such infections
should be taken seriously as tetanus shots might be required!