Notes on the Troubleshooting and Repair of Audio Equipment and Other Miscellaneous Stuff. Back to Audio and Misc Repair FAQ Table of Contents. Note troubleshooting of large audio amplifiers constructed with discrete. See. BIG Audio Power. Smoking Crack Brings The Vapors Directly And Inversely Proportional' title='Smoking Crack Brings The Vapors Directly And Inversely Proportional' />The audio amplifiers found in small radios, Walkmen, portable cassette. Obtain a pin diagram, test inputs and outputs with. A dead output where inputs. IC as does one that. Larger audio amplifiers may use ICs up to 1. W or hybrid modules. W per channel and beyond. Crack-Your-Neck-Step-20.jpg' alt='Smoking Crack Brings The Vapors Directly And Inversely Proportional' title='Smoking Crack Brings The Vapors Directly And Inversely Proportional' />Back to Audio and Misc Repair FAQ Table of Contents. Maintenance and Troubleshooting Guide SAFETY The only danger to you in most audio equipment and the other devices. Liquid intelligence the art and science of the perfect cocktail. Purists may argue about the quality. Hybrids modules called blocks or bricks by some may be totally self. Failure of these bricks is quite common. Note that testing of these op amp designs whether discrete or brick. Intermediate signals in a working channel may look like power supply. In a dead channel these same points may appear to be. In. addition, since extensive negative feedback is used, power supply ripple. One of the bricks may be shorted resulting in a blown fuse or overheating. It is usually safe to unsolder each of the hybrids. With stereo amplifiers, it is normally safe and most effective to. ALIENS. Intelligent races who are not EARTH HUMANS. The term as such is never used for nonintelligent species, however unearthly, though in TECHJARGON these may be. Issuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. Easily share your publications and get. This is by far the. I would be a lot more reluctant. There can be all sorts of sources for low level noise or static including bad. These are usually hybrid circuits multiple devices mounted on a. Think. of them as entire subsystems encased in plastic. Thus, hybrid bricks may have problems with noise especially considering that. Thermal cycling can take its toll on this kind of device. If you have eliminated other likely causes, replacing the brick would be the. Of course, if there are separate bricks for each channel. This will be relatively low. A hot air gun used carefully on the final modules might. From Andy Cuffe baltimorapsu. If it has ICs for the audio output you can just remove one of them. If. the fuse still blows try removing the other one. If the fuse blows with. ICs out you know there are problems in an other part of the. If it uses transistors instead of ICs you just need to check them with. The bad ones almost always measure close to 0 ohms. Once you find the bad pair try. You should get normal sound from the. To determine if there is more damage. Before you remove anything WRITE DOWN where they go because. I strongly recommend that you dont. I have seen. a lot of repairable electronics ruined by this type of troubleshooting. From Dakuhajda dakuhajdaaol. Where one channel still works, on old amplifiers we commonly remove output. Then bring the power. With a. working channel it should be a simple matter of making DC measurements to find. From Wild Bill kwag. A lot of the diagnosis can be accomplished with a DMM. Either the diode check. Most of these. comments are related to units with through hole components with leads circuit. If you dont possess the skills, equipment and safe working habits required to. If. you read the rest, youll discover and maybe understand why technicians. For almost any bipolar transistor output type amplifier testing, its a. A good starting place is checking key components for. Bias resistors for open infinite ohms. Transistors for shorts with the diode test. Ohms checks for the power transformer, standby transformer windings, and. Diode check for rectifiers, full wave bridge rectifiers and transistors. Capacitor testing should also be part of the diagnosis stage, particularly. Make notes of defective components, you can offer some help to someone else. Before proceeding to the stage of disassembly, check for circuit board. When these get loose, this can cause a lot of weird symptoms. Its often necessary to start unsoldering parts since a 0. In most cases. where there is no output, or the protection circuits are preventing the amp. Since the unit isnt. This method is. also more economical since parts wont be repeatedly destroyed until. Many manufacturers utilize fusible andor flameproof small wattage resistors. They might. be blue, green or tan colored. When damaged output transistors are discovered, check the driver stage for. Some driver stages use linear ICs. After a thorough check of key components, and faulty devices have been. The lamp will. usually prevent destruction of components. Instead of attaching speakers to the outputs main or front L R, use dummy. The unit. should be powered with an isolated variac. VAC will probably be a good. You could also have an. If the lamp shows continuous light output at this low variac. In that. case, disconnect everything and resume ohmmeter tests. Check for components. If a dim glow is visible, dont rush to put a fuse in and attach speakers to. AC. transformer outputs and DC voltage checks full wave bridge rectifiers, plus. Check the individual supplies DC. AC at all of the amps outputs with a. If all appears to be normal at reduced line volts, turn the unit off and. If dummy loads havent been attached to the output terminals yet, turn. With the volume control set low, there should be little heat. For amps with rear and center channels, check the main channel L and R first. This seems like a lot of backing up and rechecking, but it is an economical. Before connecting a. The situation is that after finding and replacing output transistors and. From Mike Ross mike. Before you blow up any more parts insert some temporary current limiting. W is okay in series with each individual. If the transistors saturate then there. Blown diodes and resistors in the bias voltage reference circuit could. One common design problem is. Of course they should always be. This could be one cause. Good luck. If all else fails, hurl it across the room a few times From Dave gravmanidirect. Where one channel blows outputs, check the zobel network components. This is. a capacitor usually green mylar with values of. F connected in. series with a low ohm resistor 2. BETWEEN the speaker line and. I have seen a few amps with the same symptom and the cause was. OPEN Cranking up the treble full at very high volume. Even a nearby CB or HAM transmitter with lots. When that cap goes open circuit, the amp will oscillate at a high frequency. Ive scoped as high as 8. KHZ If those two components are OK, and you have definitely confirmed that all. OK, leave the output transistors out, install a 1. W speaker. load resistor and power up the amp with a DC voltmeter in place. You. should measure much less than. DC across that dummy load. If. the voltage is more, youve got a improperly installed transistor, bad bias. Check, double check, and re check your components. If the voltage is within proper range, connect a scope across the dummy load. If you see a extremely. F. value compensation capacitors in other parts of the circuit. You may have to. pull each one and checkreplace until you find the culprit. You may simply. have a leakyflaky transistor in there somewhere. You may also have a. Do these tests, and see what you find. ALWAYS CHECK YOUR OWN WORK THREE TIMES. BEFORE CURSINGFrom Jerry Greenberg jerryg. The first step is to verify the voltages in the power supply for both the. I would also start by changing the main filter caps in the power supply to. This is the only true way to test these. The best way to test for such a problem is to feed an audio generator into the. Use a scope and go through. Set the audio generator to a 4. Hz tone. The test for the output stage is to turn up the volume with the scope across. See and measure the amplitude of the waveform to. P P output. You should see where it is starting to. From that calculate the. RMS, and then calculate the actual Power. If it is more than than the rated. Dont leave high volume tone into the dummy load for more than a few minutes. This is hard on the unit for long periods of time. Note I have found many consumer amplifiers can only put out their rated power. Hz. Only the high quality ones can do it at all frequencies. At about. 5. 0 to 8. Hz most consumer amps will only put out about 5. From Mark Kinsler kinsleradenine. The classic failure of output transistors in audio equipment is the. Aliens Atomic Rockets. So we must strike beyond physiology and reach into chemistry, saying that all life is made up of a directing set of nucleic acid molecules which controls chemical reactions through the agency of proteins working in a watery medium. There is more, almost infinitely more, to the details of life, but I am trying to strip it to a basic minimum. For life as we know it, water is the indispensable background against which the drama is played out, and nucleic acids and proteins are the featured players. Hence any scientist, in evaluating the life possibilities on any particular world, instantly dismisses said world if it lacks water or if it possesses water outside the liquid range, in the form of ice only or of steam only. You might wonder, by the way, why I dont include oxygen as a basic essential. I dont because it isnt. To be sure, it is the substance most characteristically involved in the mechanics by which most life forms evolve energy, but it is not invariably involved. There are tissues in our body that can live temporarily in the absence of molecular oxygen, and there are microorganisms that can live indefinitely in the absence of oxygen. Life on earth almost certainly developed in an oxygen free atmosphere, and even today there are microorganisms that can live only in the absence of oxygen. No known life form on earth, however, can live in the complete absence of water, or fails to contain both protein and nucleic acid. In order to discuss life not as we know it, lets change either the background or the feature players. Background first Water is an amazing substance with a whole set of unusual properties which are ideal for life as we know it. So well fitted for life is it, in fact, that some people have seen in the nature of water a sure sign of Divine providence. This, however, is a false argument, since life has evolved to fit the watery medium in which it developed. Life fits water, rather than the reverse. Can we imagine life evolving to fit some other liquid, then, one perhaps not too different from water The obvious candidate is ammonia. Ammonia is very like water in almost all ways. Whereas the water molecule is made up of an oxygen atom and two hydrogen atoms H2. O for an atomic weight of 1. NH3 for an atomic weight of 1. Liquid ammonia has almost as high a heat of evaporation, almost as high a versatility as a solvent, almost as high a tendency to liberate a hydrogen ion. In fact, chemists have studied reactions proceeding in liquid ammonia and have found them to be quite. Ammonia chemistry has been worked out in considerable detail. Ammonia as a background to life is therefore quite conceivable but not on earth. The temperatures on earth are such that ammonia exists as a gas. Its boiling point at atmospheric pressure is 3. C. 2. 8 F. and its freezing point is 7. C. 1. 08 F. But other planets In 1. Jupiter, and, to a lesser extent, of Saturn, was loaded with ammonia. The notion arose at once of Jupiter being covered by huge ammonia oceans. To be sure, Jupiter may have a temperature not higher than 1. C. 1. 48 F., so that you might suppose the mass of ammonia upon it to exist as a solid, with atmospheric vapor in equilibrium. Too bad. If Jupiter were closer to the sun. But wait The boiling point I have given for ammonia is at atmospheric pressure earths atmosphere. At higher pressures, the boiling point would rise, and if Jupiters atmosphere is dense enough and deep enough, ammonia oceans might be possible after all. An objection that might, however, be raised against the whole concept of an ammonia background for life, rests on the fact that living organisms are made up of unstable compounds that react quickly, subtly and variously. The proteins that are so characteristic of life as we know it must consequently be on the edge of instability. A slight rise in temperature and they break down. A drop in temperature, on the other hand, might make protein molecules too stable. At temperatures near the freezing point of water, many forms of non warm blooded life become sluggish indeed. In an ammonia environment with temperatures that are a hundred or so Centigrade degrees lower than the freezing point of water, would not chemical reactions become too slow to support lifeThe answer is twofold. In the first place, why is slow to be considered too slow Why might there not be forms of life that live at slow motion compared to ourselves Plants do. A second and less trivial answer is that the protein structure of developing life adapted itself to the temperature by which it was surrounded. Had it adapted itself over the space of a billion years to liquid ammonia temperatures, protein structures might have been evolved that would be far too unstable to exist for more than a few minutes at liquid water temperatures, but are just stable enough to exist conveniently at liquid ammonia temperatures. These new forms would be just stable enough and unstable enough at low temperatures to support fast moving forms of life. Nor need we be concerned over the fact that we cant imagine what those structures might be. Suppose we were creatures who lived constantly at a temperature of a dull red heat naturally with a chemistry fundamentally different from that we now have. Could we under those circumstances know anything about earth type proteins Could we refrigerate vessels to a mere 2. C., form proteins and study them Would we ever dream of doing so, unless we first discovered life forms utilizing them Anything else besides ammonia nowWell, the truly common elements of the universe are hydrogen, helium, carbon, nitrogen, oxygen and neon. We eliminate helium and neon because they are completely inert and take part in no reactions. In the presence of a vast preponderance of hydrogen throughout the universe, carbon, nitrogen and oxygen would exist as hydrogenated compounds. In the case of oxygen, that would be water H2. O, and in the case of nitrogen, that would be ammonia NH3. Both of these have been considered. That leaves carbon, which, when hydrogenated, forms methane CH4. There is methane in the atmosphere of Jupiter and Saturn, along with ammonia and, in the still more distant planets of Uranus and Neptune, methane is predominant, as ammonia is frozen out. This is because methane is liquid over a temperature range still lower than that of ammonia. It boils at 1. 61. C. 2. 59 F. and freezes at 1. Finale Notepad 2014 Free Download Italiano there. C. 2. 97 F. at atmospheric pressure. Could we then consider methane as a possible background to life with the feature players being still more unstable forms of protein Unfortunately, its not that simple. Ammonia and water are both polar compounds that is, the electric charges in their molecules are unsymmetrically distributed. The electric charges in the methane molecule are symmetrically distributed, on the other hand, so it is a non polar compound. Now, it so happens that a polar liquid will tend to dissolve polar substances but not nonpolar substances, while a nonpolar liquid will tend to dissolve nonpolar substances but not polar ones. Thus water, which is polar, will dissolve salt and sugar, which are also polar, but will not dissolve fats or oils lumped together as lipids by chemists, which are nonpolar. Hence the proverbial expression, Oil and water do not mix. On the other hand, methane, a nonpolar compound, will dissolve lipids but will not dissolve salt or sugar. Proteins and nucleic acids are polar compounds and will not dissolve in methane. In fact, it is difficult to conceive of any structure that would jibe with our notions of what a protein or nucleic acid ought to be that would dissolve in methane. If we are to consider methane, then, as a background for life, we must change the feature players. To do so, lets take a look at protein and nucleic acid and ask ourselves what it is about them that makes them essential for life.