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Q:
My (tuner, receiver, amplifier, etc.) has no sound. There used to be a 'click' before the sound came on, but now I don't hear that anymore.A:
Most receivers, amplifiers, anything that drives speaker loads, incorporate a 'protect' circuit. The protect circuit consists of a relay in series with the output of the amp section and the speaker connectors. In order for sound to come out of the speakers, this relay has to be energized. The purpose of this circuit, and it's associated relay, is to prevent damage to the amplifier section and your speakers in the event of a problem in the amplifier. The most common reason this circuit prevents the relay from energizing is a shorted output transistor. A shorted output transistor will apply whatever voltage is available from the power supply to the speaker outputs and destroy the speakers. That is why the relay will not come on. Some models have protect 'indicators' that may flash or change color when a problem is detected. The normal delay upon power up is due to the need to allow the power supply to stabilize. Simply bypassing the relay will damage the speakers and the amplifier. Many people assume the relay is defective when it won't turn on, this is rarely the case. The relay will also de-activate if the amplifier is overdriven or if there is a problem anywhere in the audio chain leading to the output devices. Beware, there is NO easy fix. Think of the relay as home security for your equipment. It will keep your receiver or amp safe as long as it's in proper working condition. Your gear will work if the relay is not operational, but it never hurts to play it safe.Q:
What is the RCA jack on the back of my (tuner, receiver) labled (quadradial, 4-ch, det out) used for?A:
That jack is a wideband output of the FM detector. It was designed to deliver a rear channel encoded subcarrier to a 4-channel FM decoder. It was intended as a "non-obsolescent" feature that would allow for 4-channel FM when the format arrived. Unfortunately, it never did. That output is pretty much useless. However, because it is a wideband output, it will drive an RDS (Radio Data System) decoder or other subcarrier decoder.Q:
When I plug my turntable into the auxilliary inputs on my new (receiver, preamp) why is the sound low and muffled?A:
When using a turntable, it must be plugged into a specific type of input usually labled "phono". Most new stereos do not offer a "phono" input because not many people still play records. The output of most turntables is very low, like a microphone. The receiver or amplifier must boost this signal to the correct level. When records are made, an equalization curve is applied to the audio being cut onto the vinyl. The receiver or amplifier must compensate for this equalization. This is all handled by the "phono stage" inside the stereo. The set of standards to which phono inputs must adhere to is known as "RIAA" (Record Industry Association of America). The "auxillary", "CD" or "tape" inputs on an amplifier or receiver do not provide the necessary amplification and equalization. Likewise, if a CD or other similar device is plugged into the "phono" input it will sound distorted. After market phono 'preamps' are available from most stereo stores.Q:
What is the Dolby FM, 25uS function on my (tuner, receiver) used for?A:
That function enables a Dolby noise reduction system decoder. Dolby FM was a system designed to reduce noise on FM broadcasts. It functioned very much like the Dolby noise reduction system found on many cassette decks. And, just like Dolby encoded tapes, the FM broadcast had to be encoded also. The broadcast station had to use a Dolby encoder for the decoder in your stereo to work correctly. A few stations did broadcast with Dolby for a short time, but none do it today. Engaging the Dolby decoder on your stereo changes the equalization of the non Dolby FM broadcast. It boosts the highs, making it sound 'brighter'. Although this is an incorrect representation of the broadcast program, no harm is done.Q:
My vintage casstte deck only plays for a short time then stops, is there a fix?A:
That is a very common problem and usually indicates something is wrong with the 'end of tape' sensor. The deck thinks it has reached the end of the tape and, as it is supposed to, shuts off. Most decks use a motion sensing device connected to the counter, or at least to the same belt that drives the counter. If the counter does not move, try 'resetting' it. If it still does not move, check the associated belt(s). Of course, it could be a more severe problem, but it is often related to a non-functioning tape counter.Q:
How do I clean the controls on my (tuner, receiver, amplifier, etc.)?A:
You must access the inside of the switch or control to apply the cleaner. This will require some amount of disassembly. On some models it will require a great deal of disassembly. See this page: http://www.classicaudio.com/forsale/bench.html
Switches with no points of entry for the cleaner will have to be carefully pried open. Since this can be a significant task, it's important to use a high quality cleaner. Doing anything less than described will not produce acceptable results.
