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Can my solid state amp kill me when it's not plugged in?

M

moulie

May 1, 2008
33
1
Toronto, Ontario, Canada
#1
So, I'm getting some crackling from either my amp or my bass. Just brought in some new cordage and nothing has improved.

Ampeg B5r and MIM P

I was thinking about opening both up and getting the lay of the land, see if anything needs some general tightening or there is anything readily apparent.

Can it kill me, or at least shock me, if it's not plugged in?

My feeling is that I'm safe, but best to ask about these things.

Thanks for the help.

And if anyone has suggestion on what the heck could be crackling, I would love to hear about it.
 
#2
its possible... the shock will come from the power supply. it is stored in the big capacitors used to rectify the AC coming from the wall...

its best to be safe and not mess around unless you know what you are doing.

the crackling could be a ton of things...

switches in your bass.. jacks in your bass... switches in you amp, pots in your amp, loose solder joints in the bass or amp....
 
#3
Yah, I knew all those things could be possible culprits.

I was hoping just to peak and see that the jacks in the amp had worked their way loose.

The bummer about the whole thing is that I'm supposed to be on my way to trade the thing in so I can get my new, most definitely awesome amp.

I'm guessing this development will negatively impact the trade in value...sigh.
 
#9
If the crackling occurs while you move around (while not playing) it's probably a dirty or loose instrument connector/contact on the bass or amp. Try cleaning them to see if it clears up the problem. Also, checking the amp with another bass (or electric guitar) will help to isolate where the problem is. Sometimes the instrument jack will develop a faulty connection or solder joint, especially if it is loose and twists. That happened with my jazz bass. Resoldering the connections fixed it.

Typically, but not always, if something overheats or fries in the amp, you'll smell it. It's usually difficult to spot damaged/faulty electronics components or cold solder joints just by opening the case and looking at it. In any case, unless you had training, manuals and equipment, you really couldn't do much on your own to fix it.

Keep us posted and good luck!
 
#10
If it has been "off" for at least a half hour, it should be OK. Not a guarantee, but everything is supposed to be discharged by then. Obviously with an amp thought to be bad, there is a chance that the parts supposed to discharge everything may be bad and not working.

However, you need to ask yourself a couple questions:

1) Would I know what was bad if I saw it?

2) Assuming I really DO find a problem, do I KNOW can I fix it without causing more damage?

Any doubt on either one is a strong suggestion to not mess with it.
 
#11
It's good to learn about your gear, but be careful with what you don't know about.

The "needs general tightening" remind me of when I was a wireless mic engineer at Sennheiser. An audio tech at a church told me he had a wireless mic system that was exhibiting some problems, so he opened up the transmitter and "tightened all the loose screws." Then it didn't work at all. It turned out that he cranked down all the tuning slugs in the RF coils and transformers. Undoing that damage took a few hours of work! ;)
 
#13
When messing with your amp, I don't think just taking the cover off, blowing the dust out and spraying contact cleaner in all the pots and jacks requires much more than common sense. Beyond that, I let somebody who knows what they're doing mess with it but that much routine cleaning will usually fix little noises like that provided there are no major problems. I'd also do the same thing with all the controls and wiring in your bass as that's often times the more likely culprit. Also check all the solder connections in the bass, those are fine little wires than sometimes with age can come loose or have a couple little strands fray off and touch somthing. I've found with experience (albeit no electrical engineering degree here) that crackles that come with moving around or turning knobs means it needs a good cleaning and/or some cutting back/re-soldering of your cables. Constant static, hiss or distorted sound can indicate a larger problem with the amp itself. You said you got new cables, have you tried different basses, speakers and speaker cables to isolate the problem solely to the amp?
 
#14
I have found during my years of working on other peoples equipment that "common" sense is very often not so common as you would think!!! I have found fuses with foil around them. A fuse replaced with a nail that one resulted in the replacement of the output transformer, choke, rectifiers and power transformer of a nice old Marshall. Needed new output tubes too.

To the OP get the amp looked at by a tech. The life you save could be your own!

Paul
 
#15
cybersnyder said:
Here's my rule of thumb: "If you have to ask and your question involves the word 'kill', let a pro do it."
Click to expand...

amen brother. amen.

i work for a tree company these days. It's amazing how many people think that they can save some money on tree work and end up in the hospital (or worse). Ditto for opening up amplifiers.

On the positive side the crackling sound is probably an easy fix not related to the amp. Even if it is related to the amp it's almost certainly a loose or worn input jack, connection to the input jack, or a dirty pot on the amplifier. all stupid easy to fix by someone who knows how not to get killed. :)
 
#16
Thank you all for your help and general concern for my well being.

as an update, I ended up taking the cover off the amp.

I looked inside, thought to myself: "Hmm, interesting," and closed the bastard right back up.

I quickly recognized I had nothing of value to add to that amp. I can clean the input jacks from the outside. I thought it was best that I avoided poking it randomly with a screwdriver.

I currently only have one bass. But i did plug a cord into the amp without plugging it into my bass and wiggled it around some. I got no crackling.

So, off came the pickguard and and I got a good look at the pots and jack in my bass. I didn't notice anything weird.

The solder points all seemed okay--very delicate work there. I was half expecting to see gobs of the stuff on each connection.

The input jack was very tight fitting. I didn't notice any dirt or oxidization on it, but I'm picking up some contact cleaner today to give everything a going over.

Hopefully I've eliminated to problem by simply staring at the potential culprits. We shall see.
 

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