A number of organizations have compiled databases covering thousands of common problems with VCRs, TVs, computer monitors, and other electronics equipment. Most charge for their information but a few, accessible via the Internet, are either free or have a very minimal monthly or per-case fee. In other cases, a limited but still useful subset of the for-fee database is freely available. A tech-tips database is a collection of problems and solutions accumulated by the organization providing the information or other sources based on actual repair experiences and case histories. Since the identical failures often occur at some point in a large percentage of a given model or product line, checking out a tech-tips database may quickly identify your problem and solution. In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts. My only reservation with respect to tech-tips databases in general - this has nothing to do with any one in particular - is that symptoms can sometimes be deceiving and a solution that works in one instance may not apply to your specific problem. Therefore, an understanding of the hows and whys of the equipment along with some good old fashioned testing is highly desirable to minimize the risk of replacing parts that turn out not to be bad. The other disadvantage - at least from one point of view - is that you do not learn much by just following a procedure developed by others. There is no explanation of how the original diagnosis was determined or what may have caused the failure in the first place. Nor is there likely to be any list of other components that may have been affected by overstress and may fail in the future. Replacing Q701 and C725 may get your equipment going again but this will not help you to repair a different model in the future. Having said that, here are three tech-tips sites for computer monitors, TVs, and VCRs: * http://www.anatekcorp.com/techforum.htm (Free). * http://www.repairworld.com/ ($8/month). * http://elmswood.guernsey.net/ (Free, somewhat limited). The following is just for monitors. Some portions are free but others require a $5 charge. However, this may include a personal reply from a technician experienced with your monitor so it could be well worth it. * http://www.netis.com/members/bcollins/monitor.htm Some free monitor repair tips: * http://www.kmrtech.com/ * http://www.metrosites.com/amr/monitor_repair_tips.htm Tech-tips of the month and 'ask a wizard' options: * http://members.tripod.com/~ADCC/ (Home page) * http://members.tripod.com/~ADCC/tips.htm (Tech-tips of the month) The Resolve Monitor Tech-Tips database is a diskette that is priced out of the reach of most hobbyists. However, a reduced shareware version may be downloaded from a number of web sites. Go to http://www.filez.com/ and look for res16sw.zip.
Note: Most of the information on TV and monitor CRT construction, operation, interference and other problems. has been moved to the document: "TV and Monitor CRT (Picture Tube) Information". The following is just a brief introduction with instructions on degaussing.
All color CRTs utilize a shadow mask or aperture grill a fraction of an inch (1/2" typical) behind the phosphor screen to direct the electron beams for the red, green, and blue video signals to the proper phosphor dots. Since the electron beams for the R, G, and B phosphors originate from slightly different positions (individual electron guns for each) and thus arrive at slightly different angles, only the proper phosphors are excited when the purity is properly adjusted and the necessary magnetic field free region is maintained inside the CRT. Note that purity determines that the correct video signal excites the proper color while convergence determines the geometric alignment of the 3 colors. Both are affected by magnetic fields. Bad purity results in mottled or incorrect colors. Bad convergence results in color fringing at edges of characters or graphics. The shadow mask consists of a thin steel or InVar (a ferrous alloy) with a fine array of holes - one for each trio of phosphor dots - positioned about 1/2 inch behind the surface of the phosphor screen. With some CRTs, the phosphors are arranged in triangular formations called triads with each of the color dots at the apex of the triangle. With many TVs and some monitors, they are arranged as vertical slots with the phosphors for the 3 colors next to one another. An aperture grille, used exclusively in Sony Trinitrons (and now their clones as well), replaces the shadow mask with an array of finely tensioned vertical wires. Along with other characteristics of the aperture grille approach, this permits a somewhat higher possible brightness to be achieved and is more immune to other problems like line induced moire and purity changes due to local heating causing distortion of the shadow mask. However, there are some disadvantages of the aperture grille design: * weight - a heavy support structure must be provided for the tensioned wires (like a piano frame). * price (proportional to weight). * always a cylindrical screen (this may be considered an advantage depending on your preference. * visible stabilizing wires which may be objectionable or unacceptable for certain applications. Apparently, there is no known way around the need to keep the fine wires from vibrating or changing position due to mechanical shock in high resolution tubes and thus all Trinitron monitors require 1, 2, or 3 stabilizing wires (depending on tube size) across the screen which can be see as very fine lines on bright images. Some people find these wires to be objectionable and for some critical applications, they may be unacceptable (e.g., medical diagnosis).
Degaussing may be required if there are color purity problems with the display. On rare occasions, there may be geometric distortion caused by magnetic fields as well without color problems. The CRT can get magnetized: * if the TV or monitor is moved or even just rotated. * if there has been a lightning strike nearby. A friend of mine had a lightning strike near his house which produced all of the effects of the EMP from a nuclear bomb. * If a permanent magnet was brought near the screen (e.g., kid's magnet or megawatt stereo speakers). * If some piece of electrical or electronic equipment with unshielded magnetic fields is in the vicinity of the TV or monitor. Degaussing should be the first thing attempted whenever color purity problems are detected. As noted below, first try the internal degauss circuits of the TV or monitor by power cycling a few times (on for a minute, off for 30 minutes, on for a minute, etc.) If this does not help or does not completely cure the problem, then you can try manually degaussing. Commercial CRT Degaussers are available from parts distributors like MCM Electronics and consist of a hundred or so turns of magnet wire in a 6-12 inch coil. They include a line cord and momentary switch. You flip on the switch, and bring the coil to within several inches of the screen face. Then you slowly draw the center of the coil toward one edge of the screen and trace the perimeter of the screen face. Then return to the original position of the coil being flat against the center of the screen. Next, slowly decrease the field to zero by backing straight up across the room as you hold the coil. When you are farther than 5 feet away you can release the line switch. The key word here is ** slow **. Go too fast and you will freeze the instantaneous intensity of the 50/60 Hz AC magnetic field variation into the ferrous components of the CRT and may make the problem worse. It looks really cool to do this while the CRT is powered. The kids will love the color effects. Bulk tape erasers, tape head degaussers, open frame transformers, and the "ass-end" of a weller soldering gun can be used as CRT demagnetizers but it just takes a little longer. (Be careful not to scratch the screen face with anything sharp.) It is imperative to have the CRT running when using these whimpier approaches, so that you can see where there are still impurities. Never release the power switch until you're 4 or 5 feet away from the screen or you'll have to start over. I've never known of anything being damaged by excess manual degaussing though I would recommend keeping really powerful bulk tape erasers turned degaussers a couple of inches from the CRT. If an AC degaussing coil or substitute is unavailable, I have even done degaussed with a permanent magnet but this is not recommended since it is more likely to make the problem worse than better. However, if the display is unusable as is, then using a small magnet can do no harm. (Don't use a 20 pound speaker or magnetron magnet as you may rip the shadow mask right out of the CRT - well at least distort it beyond repair. What I have in mind is something about as powerful as a refrigerator magnet.) Keep degaussing fields away from magnetic media. It is a good idea to avoid degaussing in a room with floppies or back-up tapes. When removing media from a room remember to check desk drawers and manuals for stray floppies, too. It is unlikely that you could actually affect magnetic media but better safe than sorry. Of the devices mentioned above, only a bulk eraser or strong permanent magnet are likely to have any effect - and then only when at extremely close range (direct contact with media container). All color CRTs include a built-in degaussing coil wrapped around the perimeter of the CRT face. These are activated each time the CRT is powered up cold by a 3 terminal thermister device or other control circuitry. This is why it is often suggested that color purity problems may go away "in a few days". It isn't a matter of time; it's the number of cold power ups that causes it. It takes about 15 minutes of the power being off for each cool down cycle. These built-in coils with thermal control are never as effective as external coils. See the document: " TV and Monitor CRT (Picture Tube) Information" for some additional discussion of degaussing tools, techniques, and cautions.
Some monitor manufacturers specifically warn about excessive use of degauss, most likely as a result of overstressing components in the degauss circuitry which are designed (cheaply) for only infrequent use. In particular, there is often a thermister that dissipates significant power for the second or two that the degauss is active. Also, the large coil around the CRT is not rated for continuous operation and may overheat. If one or two activations of the degauss button do not clear up the color problems, manual degaussing using an external coil may be needed or the monitor may need internal purity/color adjustments. Or, you may have just installed your megawatt stereo speakers next to the monitor! You should only need to degauss if you see color purity problems on your CRT. Otherwise it is unnecessary. The reasons it only works the first time is that the degauss timing is controlled by a termister which heats up and cuts off the current. If you push the button twice in a row, that thermister is still hot and so little happens. One word of clarification: In order for the degauss operation to be effective, the AC current in the coil must approach zero before the circuit cuts out. The circuit to accomplish this often involves a thermister to gradually decrease the current (over a matter of several seconds), and in better monitors, a relay to totally cut off the current after a certain delay. If the current was turned off suddenly, you would likely be left with a more magnetized CRT. There are time delay elements involved which prevent multiple degauss operations in succession. Whether this is by design or accident, it does prevent the degauss coil - which is usually grossly undersized for continuous operation - to cool.
These are not a defect - they are a 'feature'. All Trinitron (or clone) CRTs - tubes that use an aperture grille - require 1, 2, or 3 very fine wires across the screen to stabilize the array of vertical wires in the aperture grille. Without these, the display would be very sensitive to any shock or vibration and result in visible shimmering or rippling. (In fact, even with these stabilizing wires, you can usually see this shimmering if you whack a Trinitron monitor.) The lines you see are the shadows cast by these fine wires. The number of wires depends on the size of the screen. Below 15" there is usually a single wire; between 15" and 21" there are usually 2 wires; above 21" there may be 3 wires. Only you can decide if this deficiency is serious enough to avoid the use of a Trinitron based monitor. Some people never get used to the fine lines but many really like the generally high quality of Trinitron based displays and eventually totally ignore them.
Proper care of a monitor does not require much. Following the recommendations below will assure long life and minimize repairs: * Subdued lighting is preferred for best viewing conditions. Avoid direct overhead light falling on the screen or coming from behind the monitor if possible. * Locate the monitor away from extremes of hot and cold. Avoid damp or dusty locations if possible. (Right you say, keep dreaming!) This will help keep your PC happy as well. * Allow adequate ventilation - monitors use a fair amount of power - from 60 watts for a 12 inch monochrome monitor to over 200 W for a 21 inch high resolution color monitor. Heat is one major enemy of electronics. * Do not put anything on top of the monitor that might block the ventilation grill in the rear or top of the cover. This is the major avenue for the convection needed to cool internal components. * Do not place two monitors close to one another. The magnetic fields may cause either or both to suffer from wiggling or shimmering images. Likewise, do not place a monitor next to a TV if possible. * Locate loudspeakers and other sources of magnetic fields at least a couple of feet from the monitor. This will minimize the possibility of color purity or geometry problems. The exception is with respect to good quality shielded multimedia speakers which are designed to avoid magnetic interference problems. Other devices which may cause interference include anything with power transformers including audio equipment, AC or DC wall adapters, and laptop power supplies; fluorescent lamps with magnetic ballasts; and motorized or heavy duty appliances. * Situate monitors away from power lines - even electric wiring behind or on the other side of walls - and heavy equipment which may cause noticeable interference like rippling, wiggling, or swimming of the picture. Shielding is difficult and expensive. * Make sure all video connections are secure (tighten the thumbscrews) to minimize the possibility of intermittent or noisy colors. Keep the cables as short as possible. Do not add extension cables if at all possible as these almost always result in a reduction in image crispness and introduce ghosting, smearing, and other termination problems. If you must add an extension, use proper high quality cable only long enough to make connections conveniently. Follow the termination recommendations elsewhere in this document. * Finally, store magnetic media well away from all electronic equipment including and especially monitors and loudspeakers. Heat and magnetic fields will rapidly turn your diskettes and tapes into so much trash. The operation of the monitor depends on magnetic fields for beam deflection. Enough said.
Monitors normally are positioned horizontally or via the limits of their tilt swivel bases out in the open on a table or desktop. However, for use in exhibits or for custom installations, it may be desirable to mount a monitor in a non-standard position and/or inside an enclosure. (From: Bob Myers (firstname.lastname@example.org)). Your mileage may vary, but (and please take the following for what it is, a very general answer)... There are basically two potential problems here; one is cooling, and the other is the fact that the monitor has no doubt been set up by the factory assuming standard magnetic conditions, which probably DIDN'T involve the monitor tilting at much of an angle. If you're happy with the image quality when it's installed in the cabinet, that leaves just the first concern. THAT one can be addressed by simply making sure the cabinet provides adequate ventilation (and preferably adding a fan for a bit of forced-air cooling), and making sure that the whole installation isn't going to be exposed to high ambient temperatures. (Most monitors are speced to a 40 deg. C ambient in their normal orientation; adding forced-air cooling will usually let you keep that rating in positions somewhat beyond the normal.) Under no circumstances should you block the cabinet's vents, and - depending on the installation - it may be preferable to remove the rear case parts of the monitor (but NOT the metal covers beneath the plastic skin) in order to improve air circulation. Your best bet is to simply contact the service/support people of the monitor manufacturer, and get their input on the installation. Failing to get the manufacturer's blessing on something like this most often voids the warranty, and can probably lead to some liability problems. (Note - I'm not a lawyer, and I'm not about to start playing one on the net.)
Preventive maintenance for a monitor is pretty simple - just keep the case clean and free of obstructions. Clean the CRT screen with a soft cloth just dampened with water and mild detergent or isopropyl alcohol. This will avoid damage to normal as well as antireflection coated glass. DO NOT use anything so wet that liquid may seep inside of the monitor around the edge of the CRT. You could end up with a very expensive repair bill when the liquid decides to short out the main circuit board lurking just below. Then dry thoroughly. Use the CRT sprays sold in computer stores if you like but again, make sure none can seep inside. If you have not cleaned the screen for quite a while, you will be amazed at the amount of black grime that collects due to the static buildup from the CRT high voltage supply. In really dusty situations, periodically vacuuming inside the case and the use of contact cleaner for the controls might be a good idea but realistically, you will not do this so don't worry about it. (From: Tom Watson (email@example.com)). If you are maintaining a site, consider periodic cleaning of the monitors. Depending on the location, they can accumulate quite a bit of dust. In normal operation there is a electrostatic charge on the face of the crt (larger screens have bigger charges) which act as 'dust magnets'. If the operator smokes (thankfully decreasing), it is even worse. At one site I helped out with, most of the operators smoked, and the screens slowly got covered with a film of both dust and smoke particles. A little bit of glass cleaner applied with reasonable caution and the decree of "adjustments" to make the screen better (these were character monochrome terminals), and lo and behold, "what an improvement!". Yes, even in my dusty house, the TVs get a coating of film/goo which needs to be cleaned, and the picture quality (BayWatch viewers beware) improves quite a bit. Try this on your home TV to see what comes off, then show everyone else. You will be surprised what a little bit of cleaning does. (From: Bob Myers (firstname.lastname@example.org)). 1. Don't block the vents; make sure the monitor has adequate ventilation, and don't operate it more than necessary at high ambient temperatures. 2. If the monitor is used in particularly dusty environments, it's probably a good idea to have a qualified service tech open it up every so often (perhaps once a year, or more often depending on just how dirty it gets) and clean out the dust. 3. The usual sorts of common-sense things - don't subject the monitor to mechanical shock and vibration, clean up spills, etc., promptly, and so forth. And if you're having repeated power-supply problems with your equipment, it may be time to get suspicious of the quality of your AC power (are you getting noise on the line, sags, surges, spikes, brownouts, that sort of thing?). And most importantly: 4. Turn the monitor OFF when it's not going to be used for an extended period (such as overnight, or if you'll be away from your desk for the afternoon, etc.). Heat is the enemy of all electronic components, and screen-savers do NOTHING in this regard. Many screen-savers don't even do a particularly good job of going easy on the CRT. With modern power-management software, there's really no reason to be leaving a monitor up and running all the time. These won't guarantee long life, of course - nothing can do that, as there will always be the possibility of the random component failure. But these are the best that the user can do to make sure the monitor goes as long as it can.
(From: Bob Myers (email@example.com)). Most manufacturers will quote an MTBF (Mean Time Before Failure) of somewhere in the 30,000 to 60,000 hour range, EXCLUSIVE OF the CRT. The typical CRT, without an extended-life cathode, is usually good for 10,000 to 15,000 hours before it reaches half of its initial brightness. Note that, if you leave your monitor on all the time, a year is just about 8,000 hours. The only "tuneup" that a monitor should need, exclusive of adjustments needed following replacement of a failed component, would be video amplifier and/or CRT biasing adjustments to compensate for the aging of the tube. These are usually done only if you're using the thing in an application where exact color/brightness matching is important. Regular degaussing of the unit may be needed, of course, but I'm not considering that a "tuneup" or adjustment.
TVs and computer or video monitors are among the more dangerous of consumer electronics equipment when it comes to servicing. (Microwave ovens are probably the most hazardous due to high voltage at flesh frying and cardiac arresting high power.) There are two areas which have particularly nasty electrical dangers: the non-isolated line power supply and the CRT high voltage. Major parts of nearly all modern TVs and many computer monitors are directly connected to the AC line - there is no power transformer to provide the essential barrier for safety and to minimize the risk of equipment damage. In the majority of designs, the live parts of the TV or monitor are limited to the AC input and line filter, degauss circuit, bridge rectifier and main filter capacitor(s), low voltage (B+) regulator (if any), horizontal output transistor and primary side of the flyback (LOPT) transformer, and parts of the startup circuit and standby power supply. The flyback generates most of the other voltages used in the unit and provides an isolation barrier so that the signal circuits are not line connected and safer. Since a bridge rectifier is generally used in the power supply, both directions of the polarized plug result in dangerous conditions and an isolation transformer really should be used - to protect you, your test equipment, and the TV, from serious damage. Some TVs do not have any isolation barrier whatsoever - the entire chassis is live. These are particularly nasty. The high voltage to the CRT, while 200 times greater than the line input, is not nearly as dangerous for several reasons. First, it is present in a very limited area of the TV or monitor - from the output of the flyback to the CRT anode via the fat red wire and suction cup connector. If you don't need to remove the mainboard or replace the flyback or CRT, then leave it alone and it should not bite. Furthermore, while the shock from the HV can be quite painful due to the capacitance of the CRT envelope, it is not nearly as likely to be lethal since the current available from the line connected power supply is much greater.
These guidelines are to protect you from potentially deadly electrical shock hazards as well as the equipment from accidental damage. Note that the danger to you is not only in your body providing a conducting path, particularly through your heart. Any involuntary muscle contractions caused by a shock, while perhaps harmless in themselves, may cause collateral damage - there are many sharp edges inside this type of equipment as well as other electrically live parts you may contact accidentally. The purpose of this set of guidelines is not to frighten you but rather to make you aware of the appropriate precautions. Repair of TVs, monitors, microwave ovens, and other consumer and industrial equipment can be both rewarding and economical. Just be sure that it is also safe! * Don't work alone - in the event of an emergency another person's presence may be essential. * Always keep one hand in your pocket when anywhere around a powered line-connected or high voltage system. * Wear rubber bottom shoes or sneakers. * Don't wear any jewelry or other articles that could accidentally contact circuitry and conduct current, or get caught in moving parts. * Set up your work area away from possible grounds that you may accidentally contact. * Know your equipment: TVs and monitors may use parts of the metal chassis as ground return yet the chassis may be electrically live with respect to the earth ground of the AC line. Microwave ovens use the chassis as ground return for the high voltage. In addition, do not assume that the chassis is a suitable ground for your test equipment! * If circuit boards need to be removed from their mountings, put insulating material between the boards and anything they may short to. Hold them in place with string or electrical tape. Prop them up with insulation sticks - plastic or wood. * If you need to probe, solder, or otherwise touch circuits with power off, discharge (across) large power supply filter capacitors with a 2 W or greater resistor of 100 to 500 ohms/V approximate value (e.g., for a 200 V capacitor, use a 20K to 100K ohm resistor). Monitor while discharging and verify that there is no residual charge with a suitable voltmeter. In a TV or monitor, if you are removing the high voltage connection to the CRT (to replace the flyback transformer for example) first discharge the CRT contact (under the insulating cup at the end of the fat red wire). Use a 1M to 10M ohm 5 W or greater wattage (for its voltage holdoff capability, not power dissipation) resistor on the end of an insulating stick or the probe of a high voltage meter. Discharge to the metal frame which is connected to the outside of the CRT. * For TVs and monitors in particular, there is the additional danger of CRT implosion - take care not to bang the CRT envelope with your tools. An implosion will scatter shards of glass at high velocity in every direction. There are several tons of force attempting to crush the typical CRT. While implosion is not really likely even with modest abuse, why take chances? However, the CRT neck is relatively thin and fragile and breaking it would be very embarrassing and costly. Always wear eye protection when working around the back side of a CRT. * Connect/disconnect any test leads with the equipment unpowered and unplugged. Use clip leads or solder temporary wires to reach cramped locations or difficult to access locations. * If you must probe live, put electrical tape over all but the last 1/16" of the test probes to avoid the possibility of an accidental short which could cause damage to various components. Clip the reference end of the meter or scope to the appropriate ground return so that you need to only probe with one hand. * Perform as many tests as possible with power off and the equipment unplugged. For example, the semiconductors in the power supply section of a TV or monitor can be tested for short circuits with an ohmmeter. * Use an isolation transformer if there is any chance of contacting line connected circuits. A Variac(tm) is not an isolation transformer! The use of a GFCI (Ground Fault Circuit Interrupter) protected outlet is a good idea but will not protect you from shock from many points in a line connected TV or monitor, or the high voltage side of a microwave oven, for example. (Note however, that, a GFCI may nuisanse trip at power-on or at other random times due to leakage paths (like your scope probe ground) or the highly capacitive or inductive input characteristics of line powered equipment.) A fuse or circuit breaker is too slow and insensitive to provide any protection for you or in many cases, your equipment. However, these devices may save your scope probe ground wire should you accidentally connect it to a live chassis. * Don't attempt repair work when you are tired. Not only will you be more careless, but your primary diagnostic tool - deductive reasoning - will not be operating at full capacity. * Finally, never assume anything without checking it out for yourself! Don't take shortcuts!
Many problems have simple solutions. Don't immediately assume that your problem is some combination of esoteric complex convoluted failures. For a monitor, it may just be a bad connection or blown fuse. Remember that the problems with the most catastrophic impact on operation like a dead monitor usually have the simplest solutions. The kind of problems we would like to avoid at all costs are the ones that are intermittent or difficult to reproduce: the occasional jitter or a monitor that blows its horizontal output transistor every six months. If you get stuck, sleep on it. Sometimes, just letting the problem bounce around in your head will lead to a different more successful approach or solution. Don't work when you are really tired - it is both dangerous (especially with respect to monitors) and mostly non-productive (or possibly destructive). Whenever working on complex equipment, make copious notes and diagrams. You will be eternally grateful when the time comes to reassemble the unit. Most connectors are keyed against incorrect insertion or interchange of cables, but not always. Apparently identical screws may be of differing lengths or have slightly different thread types. Little parts may fit in more than one place or orientation. Etc. Etc. Pill bottles, film canisters, and plastic ice cube trays come in handy for sorting and storing screws and other small parts after disassembly. This is particularly true if you have repairs on multiple pieces of equipment under way simultaneously. Select a work area which is wide open, well lighted, and where dropped parts can be located - not on a deep pile shag rug. The best location will also be relatively dust free and allow you to suspend your troubleshooting to eat or sleep or think without having to pile everything into a cardboard box for storage. Another consideration is ESD - Electro-Static Discharge. Some components (like ICs) in a TV are vulnerable to ESD. There is no need to go overboard but taking reasonable precautions such as getting into the habit of touching a **safe** ground point first. WARNING: even with an isolation transformer, a live chassis should **not** be considered a safe ground point. When the monitor is unplugged, the shields or other signal ground points should be safe and effective. A basic set of precision hand tools will be all you need to disassemble a monitor and perform most adjustments. These do not need to be really expensive but poor quality tools are worse than useless and can cause damage. Needed tools include a selection of Philips and straight blade screwdrivers, socket drivers, needlenose pliers, wire cutters, tweezers, and dental picks. For adjustments, a miniature (1/16" blade) screwdriver with a non-metallic tip is desirable both to prevent the presence of metal from altering the electrical properties of the circuit and to minimize the possibility of shorting something from accidental contact with the circuitry. A set of plastic alignment tools will be useful for making adjustments to coils (though you can forgo these until the (rare) need arises. A low power (e.g., 25 W) fine tip soldering iron and fine rosin core solder will be needed if you should need to disconnect any soldered wires (on purpose or by accident) or replace soldered components. A higher power iron or small soldering gun will be needed for dealing with larger components. Never use acid core solder or the type used for sweating copper pipes! See the document: "Troubleshooting and Repair of Consumer Electronics Equipment" for additional info on soldering and rework techniques. For thermal or warmup problems, a can of 'cold spray' or 'circuit chiller' (they are the same) and a heat gun or blow dryer come in handy to identify components whose characteristics may be drifting with temperature. Using the extension tube of the spray can or making a cardboard nozzle for the heat gun can provide very precise control of which components you are affecting. For info on useful chemicals, adhesives, and lubricants, see "Repair Briefs, an Introduction" as well as other documents available at this site.Go to [Next] segment
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