<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by MarcusBlacksmith</i>
<br />Hey all,
Like many guitarists, I'm not very technically minded when it comes to valve amplifiers (yet).
I can gut a computer in under 10 minutes, but when it comes to high voltage electronics I gibber like a schoolgirl on LSD.
However, if I'm going to own a valve amp, there's nothing for it but to learn how to navigate my way around its innards safely. <font color="red">I mean simpler things like changing pre-amp tubes, or in my case, checking that the cable is plugged in to the reverb tank. Tube Bias is something I'm quite happy to leave to a good tech ^_^</font id="red">
So, what's the procedure? Treat me as if I'm even more stupid than I look: how do I open the amp properly (RV50H in my case).
What can I touch safely? What should I definitely avoid bumping into? Should I be grounding myself while changing tubes, etc, and what's the best way to ground myself?
How should tubes be handled to avoid damaging them?
How do I play 'Castles Made From Sand' without sounding like a dead possum? (Well, okay perhaps the answer to that question is obvious)
Look forward to your responses
![Very Happy :D](./images/smilies/icon_biggrin.gif)
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">Hey Marcus, is everyone here answering what you asked, or just telling you how to go about doing what you said you weren't going to yourself anyway...?
Yeah, big difference between the guts of a 'puter, and inside a valve amp. Don't even think about earthing yourself if you do go inside your amp. You do that inside a computer to protect its delicate ICs from damage from static electricity. Not a problem in amps - worry about protecting <i>yourself</i>! What would be a problem would be touching something hot (volts wise) while yourself being grounded. The current would then go straight through you, and the reason Jon said only ever to use one hand in the amp is to prevent that. Specifically to prevent a current going from one arm to the other, (right across your chest), and standing a good chance of stopping your heart!)
I'd say that either you want to learn the basics you can do without going under the chassis and exposing the circuitry, or else you want to learn to go in there safely. If it is the latter then listen to what Vintage Jon said about how to get rid of the high voltages safely. Be aware though that capacitors can partially 'recharge themselves' when first discharged - something called the 'memory effect'. Can give a nasty surprise, so you've been warned...
From what you are saying though I'm guessing you are just wanting some more basic amp advice. If you don't go under the chassis, (ie you can't see the circuit board), and don't poke anything into the valve sockets then you shouldn't directly come in contact with any high voltages. (And remember that the voltages in valve amps ARE high - <i>way</i> higher then mains voltage - definitely potentially deadly.
You don't need to go in there to change preamp valves of course. It is generally safe to just swap out preamp valves when sufficiently cool. Rather then just pulling them directly up out of their sockets, a slight side to side or circular rocking motion can help ease them out if a bit stiff. Note that the pins in the valve bases will only match up with the socket in one direction, so never try to force a valve back in - check the orientation is correct because 99% of the time you'll just end up bending a pin because it wasn't...
(BTW if you ever do bend a pin on a valve don't just try to bend it back - you'll likely crack the glass base. Instead a good way is to take the refill out of a ballpoint pen, silde the outer pen sleeve down as far as the bend in the pin, and gently bend it back <i>without putting any twisting force at the valve base itself</i>.)
See my post here for diagnosing 'microphonic' valves:
http://forum.orangeamps.com/viewtopic.php?t=2662
And my post here for advice on swapping preamp valves singly rather then all at once:
http://forum.orangeamps.com/viewtopic.php?t=4077
As to your reverb connections, there are no dangerous voltages, and you'll do no harm connecting it the wrong way.
(Topic currently being covered here):
http://forum.orangeamps.com/viewtopic.php?t=6411
Let us know about any more specific questions Marcus. But it is really good and wise to know your limits with HT (high tension = high voltage) circuits. Personally I let a good tech do my biasing and just check everything else seems AOK while in there. I'm well aware myself how easy it is for a small slip to become a big problem, and I'd honestly say to anyone who isn't 100% sure what they are doing just to leave it to a pro. I'm sure our resident amp techs won't argue with that too loudly... [:p]
Andy.
Only dimly aware of existence, a dimly existing awareness...
You get a wonderful view from the point of no return.