Hello, I’m a simple peasant when it comes to electric, no idea at all, shocking I know, so if possible, a simple answer would suffice. Now, I thought a spray with contact cleaner would solve my crackling pots, surely nothing can go wrong, can it??? Since I did this I’ve no sound from any guitar, only a faint buzzing when volume turned up full on my amp. I did a bit of research and discovered the pots on my amp are tiny little square things and apparently sealed? So, have I buggered up my amp in some way. Its a Mark Bass CMD 102 P 2016. Oh by the way the crackling has stopped!! Mickey
1 Like
Amp not working? Does the light come on when it’s plugged in? Try a different outlet or power cord.
If you get no sound from your amp, try to eliminate some common causes: try a different instrument cable, check to see if there’s any dirt or lint in the input jack on the amp, and on your guitar.
Have more than one guitar? Try another one, etc.
I wouldn’t spray any contact cleaner in your amp when it’s on.
Good luck and let us know what you find . . . 
Cheers
Joe
1 Like
Hi Joe, I realised after posting I should have said I tried all those things, yes lights on but no sound!!
I think I’ve checked all the obvious things and just thought I might have missed something simple. There’s no fuses, not what I can see.
I’m stumped.
2 Likes
Is there any kind of “reset” button on the back of your amp? 
Sometimes there’s a small hole that you can stick a piece of wire or a very small Allen wrench into to do this.
Try searching Google for other troubleshooting ideas.
Cheers,
Joe
1 Like
Hi Joe, nope there’s nothing I can see, HOWEVER, I’ve just tried a 3rd guitar and that worked, so I’m thinking 2 passive basses can’t be faulty surely? I tried the original guitars again and they worked!!! All seems fine now. Cheers Mickey
2 Likes
Perhaps the contact cleaner you sprayed has evaporated, and now it works?
Glad you got it sorted! 
Here is a link to a manual which you might find useful:
HTH and all best,
Joe
2 Likes
It would appear so, many thanks, I’ll have a look at the link👍
1 Like
Not sure that is the best recommendation when it comes to amps.
Do not go poking around sticking metal parts into any amp.
Assuming you have ruled out the guitar and cables, call the manufacturer, use the warranty if any, and have it exchanged or repaired.
If a relatively cheap amp and it’s out of warranty, just throw it in the garbage and buy a new one.
Never spray contact cleaner or anything else into an amp. Unless you want it to blow up when you turn it on - then carry on
4 Likes
To those thinking of taking a look inside their amp. Be aware of the scary fact that tube amps contain filter capacitors. These little guys store electricity. So even when your amp is unplugged there can be enough high voltage DC to kill or seriously hurt you.
You work round the problem by discharging the caps before working on the amp.
However I know enough to know; that my fingers don’t belong in there.
I’m going to let one of the forum experts confirm that solid state amps have capacitors as well.
Like I said I know enough to know, that I don’t know enough, to have my hands inside any of my amps.
3 Likes
Back in the day I used to service commercial and domestic miicrowave ovens.
The cases on these had about 5 safety interlock switches so that you could not power them up with the cover off. However, there is also a VERY large capacitor connected into the circuitry containing the magnetron. This capacitor is about 4"wide x 4-5" high x about 2" deep. In service courses they always said that when the case was removed to discharge this capacitor before doing anything else. When you discharged it there was quite an audible crack.
I know of several weekend handymen that have been killed because they figured they could fix their own microwaves.
Hopefully people will pay attention to what you are saying.
2 Likes