Microphone does not work
in [Hardware]
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From: Paul on 13 May 2010 15:27 jw(a)eldorado.com wrote: >> _ _ >> _____ cable cable >> Hum <_____ ********** Preamp ********* Computer >> _ _ > > The above diagram came through all messed up. Maybe you could say the > diagram in words? I would appreciate it. My guess as to what you > say is cable to preamp in---preamp out to computer in ---computer out > to speaker. Yes. Basically, I wanted an RCA cable plugged into the preamp, so you'd have the male connector on the end to work with. Then try the hum test, with the male connector. For stereo, there would obviously be two cables, and you could individually test the left and right channels. Listen for the hum, on the computer end. If it looks like the preamp is dead, and the casing has screws, perhaps you could open it up and have a look inside. If there was something like static damage to the amplifier, there would be nothing to see, so a visual inspection doesn't promise you'll find a problem. You'd only be looking for the simplest of faults, such as something that broke loose because of mechanical damage. Electronic designs have varying sensitivities to static electricity. Some RS-232 chips, are good to 15,000 volts. They did that, because twenty years ago, RS-232 level shifter chips used to "drop like flies". I had to replace several at work (MC1488/MC1489 series), and they weren't being abused or anything. Someone finally decided to do something about it, and the modern versions are pretty good. Intel USB ports are good to 5KV to 6KV. Not quite as good as the RS232 chips, but still pretty good. There are some MOSFETs you used to be able to buy, which could be destroyed with as little as 40 volts of static electricity. Those came with the leads of the transistor wrapped in a steel band. You soldered the component into the circuit, and then removed the spring steel band afterwards. The steel band was there to prevent static from getting them. I had some ICs at work, which due to a design flaw, had no antistatic protection (no clamp diodes) at all. 50% of those would die, as they slid down the inside surface of an antistatic IC tube. So that is an example of how sensitive some electronic components can be. If a part can be ruined, while housed in antistatic plastic, that is pretty sensitive. My buddy and I, designed clamp circuits and sockets for those chips, and once you had clamp diodes on all the logic signals, the chips were robust and wouldn't fail. But until you could get them into a protective socket, 50% of them would die. They were perhaps $22 a piece, and for us, a large waste of money. Fortunately, they weren't shipped as part of a product design, but as a debugging aid we provided with the product. A field tech would carry one of those, and connect it to a piece of equipment to be debugged. So that is the absolute worst piece of static sensitive stuff I've worked with. A big difference between those, and the chips that can take a 15,000 volt static electricity insult. There is no way of knowing how static sensitive your preamp is. I only mention the above examples, to show the wide range of performance available. Some electronic devices are well armored against static, and others, not so much. Paul |