Hi,newbie with some ?s

[taylor414rce2003]

Hi all I am new to this site and need some help
my .50cal(1987) has developed a noise it sounds as if it has a dirty pot all the time!! I have pulled the unit apart and have cleaned everything with compressed air but the problem is still there no better no worse.it is a constant crackling noise that is unchanged by turning any/all of the dials it doesnt matter if guitar/footswitch is plugged in or not ,no change with theA/B switch or changing ohms for speaker.any ideas would be greatly apreciated thank you and rock on :twisted:

 

[zeppman]

My guess is that it is a tube (unless you have checked that already)... most likely a pre-amp tube.

 

[taylor414rce2003]

thanks ,how can I check the tubes ? I have a meter, or do I need a specialty tool /bring tubes to a tech

 

[zeppman]

Unless you really know what your doing, I wouldn't go poking around inside the amp while its on, and I'm not if it is even possible to test a single tube by itself with a multi-meter. If I suspect a tube is going bad, I replace it with a good one, and see if the problem goes away.

I'm unfamiliar with your amp, but see if the problem occurs only in certain channels, or in all channels. If it occurs in all channels it could be the v1 position or the phase inverter. Or it could be a power tube, but I suspect its pre-amp. If it only occurs in channel 2, it could be the V2... and so on (i have a mark iv, so this is how i fix mine) If you give me more specifics I could try and pin the problem down for you. If you don't have the manual pull it off mesa's site. There should be a description of what each pre-amp tube is responsible for. If the tubes haven't been replaced for a few years, I would just replace all of them. Not only should it fix the problem, but it should make your amp sound better too.

 

[taylor414rce2003]

thanks for your help I will replace them all as I bought the amp used-any sug. on replacement tubes I am happy with whats in there but new tones are always good .I play mostly blues based rock with lots of distortion :lol:

 

[zeppman]

As far as new production stuff, I usually go with JJ electronic, SED also treated me pretty well as far as 6L6 power tubes. But actually I'm in the marked for some new power tubes myself.... if anyone else has some suggestions.

 

[LHanson]

Try plugging a patch cord across the effects loop. The switching jacks on .50 cal's are notorious for going bad.