I Didn't Even Kill Myself!

[whitebison66]

Thought I'd share an experience with the forum...

I own a Line 6 Spider Valve 112, and I had bought a Strymon SVPre tube preamp mod for it. Stock, the Spider Valve has a digital preamp, digital FX and tube/valve power section. With the mod, it's tube preamp.

Special thanks to Mayfly for helping me be super-extra-double-sure I wasn't going to electrocute myself by answering what was for him probably a painfully noob-ish question. But I almost electrocuted myself once removing wires I had been assured were dead, and so I'm a little skittish.

I didn't take photos, since I was busy and still a little paranoid. I've never worked on an amp before.

I know the mod voids the warranty, but the place I bought it wouldn't honor it anyway. That's another story: http://sean.thewhatsgoodconspiracy.com/?p=633.

I worked around the Blue Connector from Hell (I'm not making that up) by soldering the wires in question after triple-checking the placement. After that, the other three wires were almost effortless. I hooked it up and it worked!

The amp sounded good before, but it sounds great now. That tube lag and tone are fantastic.

I'm glad I did the mod, and happy I could do the work myself.

Like most of us, I'm glad I can take the DIY approach to as many parts of the guitar as possible. Thanks again to Mayfly and everyone on the board!

 

[Cletus]

Good on ya! I've been eyeing off one of those amp kits, but not yet prepared to kill myself.

 

[kboman]

I like the casual assumption both in this thread and else on the forum that fiddling with amps means instant death :icon_jokercolor:
It's probably a good assumption too, given the volts/amps involved. I wouldn't try it even if paid respectable sums of money.

 

[Firebird211]

Yeah, it only takes 50mA to stop the heart, and never grab anything with both hands that you are working on.  It's no fun to get zapped.  With a big piece of equipment like an amp even when it is unplugged the caps could discharge through you and injure or kill you.  It doesn't take much, so be careful, and always watch your hands.  Complete the circuit and... :sign13:

 

[OzziePete]

I like the casual assumption both in this thread and else on the forum that fiddling with amps means instant death :icon_jokercolor:
It's probably a good assumption too, given the volts/amps involved. I wouldn't try it even if paid respectable sums of money.

+1.

I copped a small voltage leak as a kid & never want to repeat that again. :sad:

I've seen enough warnings in forums like this, and other places, and I am definitely not about to open the top of an amp and poke around inside. I even got the jitters replacing 12AX7s on my Mesa Preamp.

 

[Cagey]

Yeah, it only takes 50mA to stop the heart, and never grab anything with both hands that you are working on.  It's no fun to get zapped.  With a big piece of equipment like an amp even when it is unplugged the caps could discharge through you and injure or kill you.  It doesn't take much, so be careful, and always watch your hands.  Complete the circuit and... :sign13:

It only takes 50 mils to interrupt your heart, but your body is a high enough resistance that without some pretty high voltage and a good connection it's tough to get that much current through you. An amplifier is certainly capable of it, but usually if you happen to brush against anything hot in there, it'll just cause your muscles to spasm and you may end up on your ass. That's what usually saves you. Definitely uncomfortable in the extreme, and if you can go your entire life without ever experiencing it, you're better off. But, while there are lethal voltage levels present that are potentially fatal, it rarely is. You're more likely to jab a screwdriver in your eye or cut yourself on the sharp edge of the sheet metal chassis.

If you really want to feel some serious voltage, the output from engine ignition coils will get your attention. It's usually between 12,000 and 35,000 volts, depending on the system. But, again, it's unlikely to kill you. It's more like a taser hit. It's very high voltage, low current and short duration. Definitely teaches you a lesson about touching it that you will not forget, though.

I've gotten zapped dozens of times over the years, and there was only any injury involved when it was something I did to myself because of the muscle spasms that occur. You end up cut/poked/bruised by something from jerking your hand away at high speed and with all your might. You can get used to it, though. Some residential and industrial electricians are bold enough to just slap bare lines with the backs of their hands to see if they're hot, because it won't end up in a grab, a short zap won't hurt you, and if you're not afraid of or surprised by it, you don't get the extreme adrenaline shot that makes it feel like you've had a heart attack.

The only time I was ever in any real danger was once when I got caught across a 480vac line in an industrial control cabinet. My hand muscles contracted around the buss bars, and I was hanging on it for grim death. Luckily, somebody saw what was happening and hit the breaker. That time, I got burned and cut pretty good. Scary stuff. Another few seconds of that, and I might not have been revivable. It would be difficult in the extreme for something like that to happen in a guitar amplifier.

 

[Firebird211]

I didn't mean to cause more fear, it's really not too big of a deal. I have to poke around electronics a lot at work, most of the time they are live so I can figure out what's wrong.  They teach all electronic techs about the safety aspect first.  I have done some electrician and lineman training as well and got to hear the same thing all over again.  I think they said that 50 mili amps is enough to interupt the heart and skip a beat or stop.  The resistance in your body depends a lot on whether you a sweating, and unfortunately if it's hot enough out or you are nervous enough, you may want to dry your sweaty palms before working on electronics.  If you are poking around with an isolated screwdriver or pliers, you are safe, not shorting anything out, or as long as you aren't working on high voltage.  The caps discharging through you would be rare, but that is all a part of the disclamer they put on electronics "don't open electric shock" .  They mean that as being that dangerous without being plugged in. The whole point of the safety course is to know some basic things about electricity's effect on the body, and to respect the fact that touching things the wrong way will cause you to be a part of the circuit.  Electrons don't care who you are, they just want the easiest path to where they are going. 

 

[lafromla1]

When I was young and stupid I had a 1968 Mustang with a 289 (V8) in it and it just wasnt sounding right.  So I popped the hood and lo and behold one of the spark plug wires looked like it had come loose.  Like an idiot, I reached for it and right when I grabbed it, electricity had arced from the plug towards the loose wire and threw my ass 10 feet in the air and 15 backwards (thank got for a DC current, huh?).  I landed on my back and felt like Ray Lewis used me as a tackling dummy.  Ever since then, I refrain from just about anything electric. Anything done in my house immediately gets the breaker off.

 

[Cagey]

Hehe! Yeah, unless you're my alter ego, "Stupid Kevin", that kind of thing only happens to you once <grin>

It's not the size of the engine that matters, though. If you ever wanna go for another superhuman flying leap, grab the spark plug lead on your lawnmower while holding onto any metal part of the chassis <grin>

 

[Firebird211]

OWWW  the pain...the pain.

 

[Cletus]

Yeah, it only takes 50mA to stop the heart, and never grab anything with both hands that you are working on.  It's no fun to get zapped.  With a big piece of equipment like an amp even when it is unplugged the caps could discharge through you and injure or kill you.  It doesn't take much, so be careful, and always watch your hands.  Complete the circuit and... :sign13:

It only takes 50 mils to interrupt your heart, but your body is a high enough resistance that without some pretty high voltage and a good connection it's tough to get that much current through you. An amplifier is certainly capable of it, but usually if you happen to brush against anything hot in there, it'll just cause your muscles to spasm and you may end up on your ass. That's what usually saves you. Definitely uncomfortable in the extreme, and if you can go your entire life without ever experiencing it, you're better off. But, while there are lethal voltage levels present that are potentially fatal, it rarely is. You're more likely to jab a screwdriver in your eye or cut yourself on the sharp edge of the sheet metal chassis.

If you really want to feel some serious voltage, the output from engine ignition coils will get your attention. It's usually between 12,000 and 35,000 volts, depending on the system. But, again, it's unlikely to kill you. It's more like a taser hit. It's very high voltage, low current and short duration. Definitely teaches you a lesson about touching it that you will not forget, though.

I've gotten zapped dozens of times over the years, and there was only any injury involved when it was something I did to myself because of the muscle spasms that occur. You end up cut/poked/bruised by something from jerking your hand away at high speed and with all your might. You can get used to it, though. Some residential and industrial electricians are bold enough to just slap bare lines with the backs of their hands to see if they're hot, because it won't end up in a grab, a short zap won't hurt you, and if you're not afraid of or surprised by it, you don't get the extreme adrenaline shot that makes it feel like you've had a heart attack.

The only time I was ever in any real danger was once when I got caught across a 480vac line in an industrial control cabinet. My hand muscles contracted around the buss bars, and I was hanging on it for grim death. Luckily, somebody saw what was happening and hit the breaker. That time, I got burned and cut pretty good. Scary stuff. Another few seconds of that, and I might not have been revivable. It would be difficult in the extreme for something like that to happen in a guitar amplifier.

That post, by itself, is enough to steer me away from ever considering building an amp kit. I don't want to feel like that.

 

[Cagey]

Building isn't for everybody. Luckily, there are plenty of people who will do it for you, or you can just buy something pre-assembled.

 

[Firebird211]

I agree with Cagey, The max danger exists mostly for 240VAC, 480+ VAC circuits.  I have seen electricians work on live circuits, or short the wires together if they want the breaker off, crazy buggers.  I usually turn the whole thing off unless I am measuring voltage.  If you are working on 240 and 480 VAC, the situation becomes more dire and carelessness can be equal to suicide.  It will more than likely grab you, or cause your muscles to hold on, or it will knock you 15 feet back on your arse.  Current kills, Voltage hurts, and Resistance is you.