Help- snap, crackle, pop Fender FM 65

[popoahi]

I'm having these intermittent pops, crackles from my Fender FM 65. can get super loud even when volume is down.

it may be one of the RCA plugs that go into the reverb box?
one of the plugs feels loose (white one) the other red one fits quite snugly.

when I try to turn the white plug in it's hole to find a quiet spot it crackles away, but it'll do it even when I'm not touching the plug or the amp.
the sounds can get scary loud.... at times it'll start a lower frequency hum not really low , say a medium low note which can get kind of loud but a slap to the cabinet or twirling the white rca plug may stop it, it can come right back I repeat the beating and might do it a few times then it won't do it for quite awhile..these 2 problems seem like they may be related???

so, playing along or when I take a break it'll start popping and crackling all on it's own, then I go fool with the rca plug or volume knobs, knock on the amp, anything.... then of course it'll stop for a short time or a long time..guess it just depends on her mood???

before I take it to the amp tech I'd like some input as to what could be causing the pop&crackles first, then the humming.??? if the popping and crackles catch you off guard just the volume will make me jump, it's that loud...

aloha guyz

[Chuck H]

You may be able to re-tension the female jack. If it's the sleeved jacket type and you cannot, buy a new cable that isn't sleeved so that you can over tension it if the problem is with the male jack. Clean the male jack with a suitable contact cleaner. Do this and see if it fixes the problem.

[popoahi]

he chuck,

it's seems the male portion of the rca type plug is making it loose going Into the female half that's on the reverb box...but I don't think it's the whole problem??
I can turn the male part to a quiet area in the plug but it stills does it,,, of course it's popping away while I'm turning the male side...(I thought of sqeezing the male plug slightly to make it tighter)
could it also have something to do with the ground???
when I touch the very tip of the guitar cord (the end that plugs into the guitar) it makes a big buzzing sound,,, what could this indicate??? I'm thinking a poor ground somewhere???
could all of this,, the loose RCA male plug going into the reverb box,,, and poor ground indicated by the buzzing when I touch the tip of the guitar jack cause all of the popping and crackling???
the amp tech came over and said it was all due to the loose male RCA plug going into the reverb box that's causing all the popping & crackling...
sometimes when I have the amp on just sitting there it'll start making all the sounds all by itself....
even when I have it on the clean channel it'll pop and when I touch the very tip of the guitar cord jack the buzz is worse,,super loud even with the volume only at 1.5 or 2,,,,if I put the volume at 5 the buzz is so loud it could damage the speaker...whats with the tip of the jack??? doesn't that have something to do with the ground???

I probably am explaining this all wrong??? I don't know how to really explain all this.... and trouble shoot it properly???
sometimes when it pops either on the clean channel or the reverb gain channel the pops so loud I think it could blow the speaker?

tell me how to trouble shoot this problem properly please.....BTW I have cleaned the RCA plugs with electrical cleaner and put a little Boeing T-9 spray ( it's a waterproof electrical spray developed by Boeing aircraft) the only thing left to do is squeeze the male plug a bit to make it go in a little more snuggly..
thanks, popo

[The Dude]

1) If you haven't already, do retention the plug so it fits nice and snug.

2) The hum you hear when touching the input cable tip is normal.

3) Does the popping and cracking go away when all of the volumes and reverb level control are down? This will help us determine what stage the noise is coming from.
I suspect you have a cold solder joint somewhere. You might try carefully tapping around the chassis with a chopstick or something non-conductive to see if you can narrow down where the problem is.

Edit: I believe this is a solid state amp? If you have a scope, unhook the speaker and watch the output on the scope while you're tapping. It will save you from damaging the speaker if the noise is extreme enough to do so.

[olddawg]

Dif amp?

[popoahi]

whats Dif?

[popoahi]

hey dude,

I forgot to tell you my amp tech did look for cold solder joints and was unable to find any..it was my suspicion that it was the problem of the amp cutting out.
he said he just cleaned it up put it back together and since then it hasn't cut out anymore... now it has these different problems...

I don't have a scope I assume you,re talking about a oscilloscope??? I have a digital scope that checks voltage, continuity, ohms, resistance, stuff for my car.
could I use this to check for something that might point to the trouble??

thanks, popo

[Jazz P Bass]

It's a mass produced combo amp.

Resolder it.

And clean & lube all of the pots & jacks.

[The Dude]

^^^^^^ What Jazz said. There are times when it's quicker/less time consuming to just get out the solder iron and start soldering than to poke around for hours looking for cold solder. Sometimes cracks are obvious, sometimes not so much. The fact that you can slap the cabinet and make the noise go or stop tells me you definitely have a connection problem of some sort.

[popoahi]

Dif, ok yup it is.

got the amp for a couple hundred bucks I don't know how much resoldering it would cost? I would think there's a lot of joints to do in there?
the main problem is the loud popping, and some crackling sounds. would these be due to a bad solder joint? or just the buzzing, and humming?
I guess I can live with the humming? it's the popping I need to fix...

I use this amp just for playing my bass as even my twin reverb can't handle the volume...I can play louder with this amp than the twin...the twin sounds distorted, like the paper cones are soft?
it's like the speakers would get damaged at similar volumes, you would think the big amp could handle it? maybe my twin's spkrs are to old and soft?

anyway I'll ask what the cost of resoldering will be and see if it's worth it? I'm not sure if I could trust taking it apart myself and my soldering skills aren't adequate?
I tried soldering something not to long ago and it wasn't pretty. (practice makes perfect I guess).

I found out the hard way why the previous owner sold it to me, it worked fine for 5 min.

you know the only amp that hasn't given me trouble is my vox that I got new. used-3 fenders,a gibson, boogie.
just frustrated, I'll get over it..

[popoahi]

can I just run the gun over the joints and re-melt it or does it really have to be cleaned and do a totally new joint?

[The Dude]

Have you tried, as I suggested in an earlier post, seeing if the noise remains when the volumes and reverb are down? This would tell us if the problem is in the preamp or power amp/power supply section. At any rate, if you don't trust your soldering skills, you should find someone with such skills to handle the job.

[The Dude]

can I just run the gun over the joints and re-melt it or does it really have to be cleaned and do a totally new joint?

I would not use a gun. They produce far too much heat and are not precise enough for the job. Use an iron. No cleaning necessary. Just reheat all of the joints and add a touch of solder to each one.

That said, if you are inexperienced at soldering, I would take it to someone who has the skills. It would be easy for you to make things worse by lifting pads and/or creating solder bridges.

[Jazz P Bass]

That is all I do.
Hit the component & then the joint & add new solder.

[popoahi]

well right now Ive been playing with it for a half hour and when volume and reverb are turned to 1 it hasn't happened.but it is intermittent...
tried each individually and together.


so right now I'd have to say it doesn't happened when volume and reverb are at #1...


and like I said earlier sometimes I can stop the loud humming by slapping the amp. but this is a secondary problem, (I think)...