Application Note 41 - Flood-damaged Electronic
- 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.
- Connector problems
- These may be present from the moment the equipment is re-assembled or they may 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.
- Other problems
- 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 the manufacturer.
We'll begin with refurbishment of the more complex electronic equipment. As you will 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 go 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 can 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 treated.
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 or 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 event that the capacitor has shorted out internally, for it might rupture
its case explosively.
Don't attempt to replace a fuse that blows with a larger one. If one of normal rating blows, it is usually better to assume a capacitor has shorted-out.
- Cooling fans
- 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 cleaning.
- 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!
- Floppy-disk drives
- 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, DVD and other optical drives
- Contact the manufacturer or the manufacturer's service center.
- Computer Keyboards
- 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, they 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 silicone 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 the print-head.
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 the manufacturer!
- 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 questions.
- 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 dishwashers, 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 under the effect of an electrical 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 single component resident solution to virtually all
When applied to electromechanical contacts, Stabilant 22 can provide the connection reliability of a soldered joint without bonding the contact surfaces.
- Where can Stabilant 22 be used?
- Stabilant 22 can be used in all types of connectors, at frequencies from to DC to several gigahertz, on fader's or potentiometer's, 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 material which through a synergistic combination of effects enhances conductivity within a contact without causing leakage between adjacent contacts. Thus large quantities of the material do 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 exceptional calibre. In many cases
the use of Stabilants can thus increase the efficiency of existing staff as well as allowing many
connector harness related problems to be handled at a much lower cost.
Many of our users have reported savings of from $250 to $3000 as a result of using $3 to $5 of the material. 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 artefacts which can disrupt data flow. Stabilants can cure these problems.
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 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 artefacts which can disrupt data flow. Stabilants can
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 capacitive 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 tunnelling, 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), an isopropyl
alcohol-diluted form (Stabilant 22A), and an ethyl alcohol diluted form (Stabilant 22E).
For example, 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. Another form
of packaging is available. Stabilant 22S packages the concentrate such that it occupies one-fifth the
volume of an otherwise empty container. This allows the end-user to add his own diluent, and thus saves the
added costs of shipping the diluent (e.g.: isopropyl alcohol), as well as allowing the end-user to use an
alternate diluent such as one of the Freon-based solvents.
In addition a 0.5 ml vial of Stabilant 22A is available for manufacturers to include with plug-in circuit boards
- 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 alcohol diluent serves ONLY to carry the concentrate into the connector.
- What is the best way to apply Stabilant to a contact?
- The 15 ml (and the 50 ml) container have "controlled-dropper" type caps that allows Stabilant 22A to be applied directly to such components as socketed IC's, switches, connectors, etc. Some end users prefer to use industrial syrettes to apply the material. Camel's hair brushes can be used to brush it on card-edge connectors or they could be dipped into the dilute material. Most metering type liquid dispensing systems can be used as well.
- What packaging is available?
- Many manufacturers make large volume purchases, diluting the material for specific applicators used on their production
lines. We can supply the concentrate (Stabilant 22), in 0.5 mL, 15 ml, 5O mL, lOO mL,
25O mL, 5OO mL and 1 litre bottles. The dilute (Stabilant 22A or Stabilant 22E, the
latter which is available in a limited number of bottle sizes except on special order), are available in 5O mL,
lOO mL, 25O mL and 5OO mL containers. We do not have a 1 litre 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 next day that they are received. ( On large quantities , more time
may be required) For companies which want to use the material as a stock store item, we can produce custom labels with
your part or stock number. The 15 mL sizes are in dropper bottles, and these are available on request for the
50 mL sizes as well.
Custom labelling has been provided for many manufacturers who wish to assign their own stock control number, or to distributors who wish to market the product under their own logo. Obviously this requires purchase in of the product in suitable quantities.
- Is it available in a spray can?
- No. Why waste the material? We would like to think we are environmentally responsible and safety conscious. This ruled out
the use of either a chlorofluorocarbon or highly inflammable mixture of butane and propane as a propellant.
In addition even Stabilant 22A for example, has only about 71200th 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, therefore, becoming the treatment of choice for many service organizations!
- Just how much should be used?
- Normally, a final film thickness of from 0.5 to 2 mils of the concentrate is all that it necessary. In other
words, you want just enough to fill up the interstices between the contact's faces. When using Stabilant 22A,
or Stabilant 22E, use enough so that once the isopropyl alcohol (or ethyl alcohol), evaporates the desired
0.5 to 2 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 occur.
- What is the 15 ml 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 15 ml dropper bottle of Stabilant 22A and some applicators, all in a small capped cardboard tube that can be tossed into a tool box without damage. As noted, we can provide these kits with special labels when large volume orders are involved.
- Does the action of Stabilant deteriorate with age?
- In some field trial applications lasting over fifteen years Stabilant 22 has shown no sign of reduced effectiveness. With a high molecular weight and a very low vapor pressure, little is 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. Unlike non-saturated oils, Stabilant 22 does not "varnish".
- How can I be sure that Stabilant works?
- The best way to find out just how well it works is to try it out; that's why we have samples available. Almost every service shop or manufacturer has equipment available where the switches or connectors have become erratic over the years. Use Stabilant 22/22A/22E on them and satisfy yourself. A word of caution. Don't try to evaluate Stabilant 22's performance on brand new connectors. Instead, use it on connectors that are corroded, or dirty or just plain unreliable. We are sure that any organization dealing with electronics will have at least one piece of unreliable equipment on which the Stabilants can be tested!
- Is Stabilant hazardous to use?
- Stabilants have very low oral toxicity. Under normal workplace conditions no skin sensitization effects have been noted. In the undiluted form, it is non-flammable although if heated above 200° Celsius the decomposition products would burn. And Stabilants are environmentally friendly materials.
- Can Stabilant be used by untrained personnel?
- Thousands of applications of the consumer version of Stabilant 22 have been made over a period of several years now without any reported problems.
- CAUTION - SEWAGE CONTAMINATION!
- 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!
Stabilants™ are a product of Dayton Wright research & development and are made in Canada
NATO Supply Code 38948
15 ml of S22A has NATO Part # 5999-21-900-6937