Crackly pots repair ?

[fathom]

Greetings all -

I have an older Gorilla 35W amp from 1985 that's been sitting unused for some time.  It's by far a great sounding amp but it's small and does the job for practice.  It has master volume, tube crunch, and the 3 tone controls.  Trying to resurrect it recently, I found that all the pots except the bass and mid get crackly and cut out until I fool with them a bit, after that they usually have a mind of their own, often sporadically cutting in and out with loud pops and whatnot.  I think the jack is giving me some flack as well, but can't be to sure with all the other crackles.

I took a look inside everything looked and felt snug and tidy.  My initial thought was to simply repair the offending pots with new ones, but it occurred to me there might be something more to it than that.  I've never opened up an amp before and aren't sure on what else could be a factor in this problem other than pots gone bad. 

Any ideas on what, if anything I could/should take into consideration before making repair attempts?  I've heard pots need to be cleaned every now and then, it couldn't be that simple could it?  Last question is, with amp unplugged of course, could I still get shocked from fiddling around inside of a ss amp?

[joecool85]

First things first, yes you could get shocked even with it unplugged.  However, an SS amp won't kill you, it'll give you a 35-40v shock that'll get your attention though.  I've never been shocked by one, and I don't want to be so I'm carefull.  If you are worried about it you will need to drain the power caps.  Here is one of the best explainations on this I've ever read:  http://studentweb.eku.edu/justin_holton/caps.html 

That is for tube amps, but the same things apply for SS amps with the exception of instead of dealing with 500v you are dealing with 50v or less.

Now for the amp fixing part.  Yes, very frequently you can use a cleaner (from radio shack or what have you) to clean the pots and jacks.  I have had this happen before were I had a pot I thought was completely unusable and it just needed cleaning.

If that doesn't work, you will want to resolder all of the joints for all of the jacks and pots.  By resolder I mean just reheat each joint then let cool.  If any of them look like they don't have enough solder you can add a bit while doing this.  It is very common for cheap amps to have cold solders where you get cracks in the solder and that makes for a noisy amp.

Lastly, if those two things don't work you will need to replace the pots/jacks that are causing noise.

If you have any more questions, please ask.  And welcome aboard!

[fathom]

Thanks, I'll give that a try.

[R.G.]

Crackle on pots is often a sign that they have DC across them. If signal pots have DC on them, that's almost always a sign that something is wrong and letting DC through. Check the pots for DC voltage with a voltmeter.