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If you have a hot chassis, there will not be any aux. inputs/outputs. However, that doesn't necessarily mean that if there are no aux. in/out jacks that the chassis is hot. If you look inside, there will be no transformer connected to the AC power line on a hot chassis. That is the main savings, elimination of the ac power transformer. Many tube table radios/phonographs of the 50's did this to eliminate all transformers. Most small TV's made today are hot chassis types. There might be an audio output transformer, two leads of which would be connected to the speaker output (times two for stereo) in which case the speaker terminals may or may not be hot, depending on whether the output transformer is of the isolating type. Kids, don't do this at home without adult supervision: The way to measure this is to use an ac or dc voltmeter, and measure either of the speaker terminals with respect to ac (earth) ground. You can use the metal case of any grounded appliance as ac ground, or the ground wire of a three wire groung plug. The voltage will be somewhere around 50vdc, or 60v ac. Could be more or less. It is actually a "half-wave rectified waveform", containing both dc and ac components. It is the ac that causes the heart to go into fibrillation. -----Original Message----- From: Edward_Chang@mail.amsinc.com [mailto:Edward_Chang@mail.amsinc.com] Sent: Wednesday, September 02, 1998 1:46 PM To: Loopers-Delight@annihilist.com Subject: RE: Old amps, was Re: Far out man! At this point I'm getting nervous about this tube-powered turntable wiring. How do detect a hot chassis? Can I do that with a multimneter? Up until this point I've been wiring the cartridge leads directly into output jacks, disconnecting them from the circuit boards completely. Somebody had mentioned that turntable circuits have some eq built in to "normalize" the cartridge frequency output, which is why I wanted to try the speaker outs, but it doesn't sound that bad with some mixer eq anyways (and I'd hate to have a shocking revelation). We'll see. But the idea about the potentiometer sounds good, can I use that same technique for battery operated toys, like Casio keyboards and hand-held video games, etc...? That sounds safer at least....to be honest, I'm pretty much a beginner so I'm trying to do things a little at a time.... Again thanks for all the help! Ed Dave wrote: Dave Stagner <dstagner@icarus.net> on 09/02/98 01:10:59 PM Please respond to Loopers-Delight@annihilist.com To: Loopers-Delight@annihilist.com cc: (bcc: Edward Chang/AMS/AMSINC) Subject: RE: Old amps, was Re: Far out man! Alan raises a good point about the possibility of a "hot chassis"... and if he's right, you should not use that turntable in a circuit with any other audio equipment. It's a hazard to EVERYTHING. You can possibly isolate it using a low-current isolation transformer, but ultimately it is a very dangerous piece of equipment. Even in high-voltage tube amps (a tube guitar amp can have upwards of 500v!), the most dangerous part by far is the AC mains. Power transformers limit the heart-stopping current. For more on electrical safety when working on tube amps, check out http://www.bottlehead.com/valve/safety.shtml -dave Practice beautiful randomness and act kind of senseless. <dstagner@icarus.net>