Fried my Denon Receiver

[highfigh]

It didn't look like the company was in compliance, not by today's NFPA 70E for sure.
Most people don't realize copper expands 67,000 times when vaporized.

We digressed, but hopefully it reminds people the danger of electrical equipment, yes even around HT equipment, is not just shock hazard but also arc flash hazard. An small explosion from an AVR could cause some seriously injury too depending on the conditions under which it occurred. I would say even for experience technicians, they should consider PPE, safety glasses with full side shield would be a minimum imo, when working on things like AVR with the case open. Unless one is trained properly, one should leave troubleshooting their AVR, amps etc., to qualified technicians.

Is there any requirement for electricians and techs to be able to smell? I saw a news report about a house explosion where the father kept repeating "All I did was plug in the coffee maker and the kitchen exploded". Turns out, the fireplace had a gas insert for Propane that was installed before they bought the place and it had been leaking.

 

[PENG]

Is there any requirement for electricians and techs to be able to smell? I saw a news report about a house explosion where the father kept repeating "All I did was plug in the coffee maker and the kitchen exploded". Turns out, the fireplace had a gas insert for Propane that was installed before they bought the place and it had been leaking.

Interesting question, I lost count how many electricians/designers/engineers I interviewed in my long EE career and have never ask any of them questions on their ability to smell, or even to see color. If I had ever thought of it, I would have consult HR and let them do their part. Thanks for raising this point, all else being equal, I would have preferred to hire one who can smell and not color blind, if permissible under the laws obviously.

 

[PENG]

The protection circuit in an amplifier is a simple thermocouple screwed onto the heat sinks and if the resistance is in the 'HOT!' range, it will trip immediately upon power up after the initial incidence- common sense says "Feel the amp/receiver to find out if it's hot", but.....Denon's light flash has three states- only one denotes overheat and it's not usually a persistent code, as it would be in a car's ECM and even that isn't actually permanent- it usually goes away after a specified number of key on events, in order to make it possible for a mechanic to see that it overheated even if the car owner tries to hide that information. At the risk of making these more complicated than necessary, it wouldn't be a bad thing if AVRs had a hidden menu area where diagnostics could be performed but the fact is, if they have a very low % of failures, why bother?

Okay, but I do know (I have service manuals) their newer models have overcurrent protection that actually sense current, so in additional to thermal, they do have the ability to shutdown based on high enough instantaneous current such as under near short circuit condition. This is something that could be hard to do in the old days when there is much microprocessor power on board to do the job well.

Again on the newer models for sure, the SM does provide ways to display the fault so you can tell if it had previously shutdown on thermal O/L or a high speed S/C (high current) protection shutdown.

 

[highfigh]

Interesting question, I lost count how many electricians/designers/engineers I interviewed in my long EE career and have never ask any of them questions on their ability to smell, or even to see color. If I had ever thought of it, I would have consult HR and let them do their part. Thanks for raising this point, all else being equal, I would have preferred to hire one who can smell and not color blind, if permissible under the laws obviously.

I worked for a big box store when I did car audio and one of the shop managers was color-blind. How he did that job as an installer is beyond me but his color-blindness wasn't his only problem- he was a terrible installer.

Yeah, ADA probably requires hiring people with these disabilities.

 

[highfigh]

There's something I never give much thought about, what if a Electrician is colorblind.

Not being colorblind, I don't know how they perceive various colors, but seeing the examples in this link, I can definitely understand why/how someone would have a problem with the insulation colors.

Types of Colour Blindness - Colour Blind Awareness

www.colourblindawareness.org

 

[TankTop5]

An electrician left this next to my desk at work over the weekend.

 

[Kai]

Lock Out, Tag Out...TEST ! whew glad you survived. i''ve never trusted others to do their job correctly...inspect, test...

 

[Tachead7075]

I just checked with a meter. The knob was in fact wired wrong as TLS Guy stated. You would have thought the media installer when they built the house would have noticed that.

I would tell them they are buying you a new AVR and fixing their install for free as you can probably force the issue in court if necessary.

 

[stalag2005]

I was almost bit myself by flashover from a variac transformer that arced over due to worn brushes. Our equipment with 100+ watts per channel is enough to kill if we get it wrong. Please be safe!

 

[Mr._Clark]

Thanks.

It's not 'usually' unless they work for themselves and don't know or if the company doesn't make sure their installers KNOW how to do this stuff.

I've never seen a system that was installed by pig dribble, but to my mind it would actually be an impressive achievement. I'd go so far as to say it would be the Great Pyramid of Giza of the pig dribble world.

 

[highfigh]

I've never seen a system that was installed by pig dribble, but to my mind it would actually be an impressive achievement. I'd go so far as to say it would be the Great Pyramid of Giza of the pig dribble world.

I worked on a house that had been wired by another shop in the area- when we were looking around to see where we would be running wires, I looked up and saw a speaker wire that was stapled to a floor joist. By itself, that's not a problem- cable staplers aren't expensive and it's a good way to secure them but this wire went to a speaker that was part of the distributed audio and in order to level the output from the different speakers, a wire-wound resistor had been soldered in series and was in direct contact with the wooden joist. You might know that resistors, especially when they're connected to an amplifier's output, get hot. Sometimes, VERY hot. This one had done that and the joist had a 6" circle where the wood was charred black.

Does that qualify?

 

[Mr._Clark]

I worked on a house that had been wired by another shop in the area- when we were looking around to see where we would be running wires, I looked up and saw a speaker wire that was stapled to a floor joist. By itself, that's not a problem- cable staplers aren't expensive and it's a good way to secure them but this wire went to a speaker that was part of the distributed audio and in order to level the output from the different speakers, a wire-wound resistor had been soldered in series and was in direct contact with the wooden joist. You might know that resistors, especially when they're connected to an amplifier's output, get hot. Sometimes, VERY hot. This one had done that and the joist had a 6" circle where the wood was charred black.

Does that qualify?

I think yer getting warm!

We bought a cottage a few years ago. It was a little shop of electrical horrors. The old metal light fixtures were nailed directly to the wood ceiling joists and the joists were charred black due to the heat. We completely replaced everything.