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Another "shocking" story [message #9418] Wed, 16 April 2008 07:18 eltumi Messages: 26 Registered: April 2008 Location: Raleigh, NC Junior Member I just just replaced the mid pot on my Charger. When I got home, I just placed the head on top of the cab with the amp x-isters over the edge, just in case of heat. It sounded good, I got better adjustment than before. I left it plugged in and before I went to bed, I used my finger to check the heat of the x-isters, which I had never done since I've had it. I got an electric bite from the back one. I have a 3-prong that was installed before I bought it, but I flipped the polarity switch and tried it. Doh, bit again! When I get to work (I left my meter there yesterday), I'll be checking voltages to x-ister case as well as ground of the "new", non-factory 3-prong. Does anyone have any ideas? Michael Report message to a moderator

Re: Another "shocking" story [message #9419 is a reply to message #9418] Wed, 16 April 2008 09:41 C4ster Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee... Senior Member If these are standard T03 metal case transistors, the case is the collector and will have 40 volts DC or more on them. If they are the typical Kustom "totem pole" arrangement and not complimentary, then only 1 or 2 will have +40 volts on it, the other 2 will be approximately 0 volts to the chassis. Conrad Report message to a moderator

Re: Another "shocking" story [message #9420 is a reply to message #9419] Wed, 16 April 2008 10:28 eltumi Messages: 26 Registered: April 2008 Location: Raleigh, NC Junior Member That explains THAT. I'm gonna peak at the condition of the insulators and the lifeguard nose grease , since I have them on my mind. Couldn't hurt. Lifeguard nose grease comment brought to you by Bill Ellis, High School Electronics 101 Instructor, circa 1977. Report message to a moderator

Re: Another "shocking" story [message #9421 is a reply to message #9420] Wed, 16 April 2008 12:15 C4ster Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee... Senior Member OK, you need to explain the "Lifeguard Nose Grease" to me. And maybe others. Conrad Report message to a moderator

Re: Another "shocking" story [message #9422 is a reply to message #9421] Wed, 16 April 2008 13:12 eltumi Messages: 26 Registered: April 2008 Location: Raleigh, NC Junior Member Zinc oxide. Thermal grease. Lifeguard sunburn nose protectant. http://en.wikipedia.org/wiki/Thermal_grease http://en.wikipedia.org/wiki/Sunscreen Report message to a moderator

Re: Another "shocking" story [message #9423 is a reply to message #9422] Wed, 16 April 2008 13:42 C4ster Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee... Senior Member I didn't realize that the 2 were the same thing. The case of those transistors are insulated from the chassis with zinc oxide and a mica washer. The screws are centered with plastic spacers and the entire thing floats above chassis ground at 40 volts. That voltage isn't lethal but can tingle a bit. Certainly don't short the transistor to ground under any circumstance. If there are 4 power transistors, 2 are paralleled in 2 pairs. They are all similar to 2N3055 and the positive pair are +40 volts above the chassis and the negative pair are roughly at 0 volts to chassis ground. The negative power supply is connected to the emitter pin and is inside the chassis and protected. So that is why only 2 are "hot" voltage wise. Conrad Report message to a moderator

Re: Another "shocking" story [message #9424 is a reply to message #9423] Wed, 16 April 2008 19:20 eltumi Messages: 26 Registered: April 2008 Location: Raleigh, NC Junior Member It's cool on the not knowin'. I was lifeguardin' during highschool and the instructor amazed himself by providing that little tidbit to the class and said to hit me up, in a pinch. I took 'em out, regreased. Mica looked good. Put 'em both back and ohmed and it's all good. Did they have a sheet of plexi or anything covering the cavity or was it open like that from the factory? Just curious. Report message to a moderator

Re: Another "shocking" story [message #9427 is a reply to message #9424] Thu, 17 April 2008 09:38 C4ster Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee... Senior Member I have absolutely no knowledge of Chargers or any of the later T&R. I have 100's and 200's and 1 little combo. Conrad Report message to a moderator

Re: Another "shocking" story [message #9428 is a reply to message #9427] Thu, 17 April 2008 12:05 chicagobill Messages: 2005 Registered: April 2003 Senior Member No cover over the output transistors of your amp. They are located out of normal reach, so no reason to block the airflow to them. Under current regulations, they probably would need to be covered with a insulated, grounded, heat resistant, metal grill, to keep people from being able to touch, lick or otherwise come into contact with anything that could hurt, harm, scare or otherwise threaten their safety. I don't know if the zinc oxide nose goop is the same as heatsink grease, but I know I'd never put the Wakefield stuff I use on my nose. I hate it when I just get the stuff on my hands. Report message to a moderator

Re: Another "shocking" story [message #9429 is a reply to message #9418] Fri, 18 April 2008 06:24   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member These days their would be a warning label the size of the whole back of the amp, and in four different languages!! Report message to a moderator

Re: Another "shocking" story [message #9430 is a reply to message #9428] Fri, 18 April 2008 06:34 eltumi Messages: 26 Registered: April 2008 Location: Raleigh, NC Junior Member chicagobill wrote on Thu, 17 April 2008 12:05 Under current regulations, they probably would need to be covered with a insulated, grounded, heat resistant, metal grill, to keep people from being able to touch, lick or otherwise come into contact with anything that could hurt, harm, scare or otherwise threaten their safety. Yeah, who'd be dumb enough to touch the darn things, huh. I don't know if the zinc oxide nose goop is the same as heatsink grease, but I know I'd never put the Wakefield stuff I use on my nose. I hate it when I just get the stuff on my hands. Not much difference. Check out some older movies that would have a lifeguard. I didn't watch it, but I'm sure the folks on Baywatch were too cool for that. Report message to a moderator

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