My Mesa Express is trying to emulate a bad tuned radio :-(

[MrRFasters]

Hi Guys.

I'm the recent proud owner of a Mesa Expres 5:25 12". I'm from Holland. It's the tan / light brown thing. It has this nice Lone Star looks going for it.

I've had it for a few weeks now and it started out very quit. So therefore I know it cán be very quit. But now there is coming a nasty sound from it. Like it's a bad tuned radio station. It's like the atmospheric background noise old radios pick up. It's not so much a high pitched Hiss, it's more like Atmospheric Noise.

It does not so immediate on start-up, but after a little while (maybe a minute or so), it does it on all channels, it is NOT dependent at all on Gain or Volume settings, it does it also when no cable is going in (so bad-cable antenna-function-input ruled out), it does it when a high quality guitar cable is in, it does it (but less) on a grounded electric socket (but somewhat less, not much), it does not rely on lights being on or off.

It actually sound like some bad isloation on cables and contacts within the amp. Could that be? Is this where Mesa found the cost-effectiveness on this amp?

It this the typical sound when a tube is out?
Could it be a loose tube?
Could it be a faulty tube ?
Or does it sound like a more serious problem?

If anyone has a clue, you would do me a great favour.
I like to be well informed when I return the thing to the dealer.
I'm a little worried I get this "This is how it's ought to be" storyline ...

 

[Mark 63]

Check if all the tubes are well seated in their sockets first. Could be just a loose tube.

 

[MrRFasters]

Thanx Mark.

Can I do this myself or would it be a better idea to get it over to the dealer?
I'm not dumb, but not a well skilled engineer either.

Unscrewing the back tube safeguard seems pretty easy and two tubes can be seen perfectly, but the others seem to reside in some tube cover. It's an easy job?

Thx, Rob.

 

[EtherealWidow]

Super easy job. The most difficult thing about it is just making sure your hand fits. The covers on the preamp tubes just screw off. I don't know how the wiring is in the Netherlands, but here in the US I just use one of these. http://www.google.com/images?um=1&hl=en&biw=1279&bih=680&tbs=isch:1&sa=1&q=3+prong+to+2+prong+adapter&aq=0&aqi=g2&aql=&oq=3+prong+to+

Super easy fix. I have a furman power strip, because I can't really afford a power conditioner. I was still getting quite a bit of radio frequencies, so a friend gave me one of those 3 prong to 2 prong adapters. Cleared the noise right up. Super quiet amp now.

 

[Mark 63]

If you use a 3 prong to 2 prong adaptor how is the circuit grounded?

 

[EtherealWidow]

There's a small tab at the bottom with a hole in it. You take the screw that's holding the faceplate to the outlet on and use it to screw that tab down. The ground goes to that little tab. My friend, who is much smarter than me, said that "Instead of grounding it to the entire house, you're now grounding it to that particular outlet." Maybe I butchered his words. All I know is that I spent about $1.50 for a pack of 3 of them, got rid of all kinds of ugly noise, and my amp isn't broken in the slightest. Haven't had a problem with my amp in over the year I've owned it.

 

[Wolfboy1]

I've got this same amp (ie. cream colored modle) and the EXACT same problem. I thought it was tubes but I changed them all and still, once the amp is on for a bit it starts getting the same **** noise. I use a EBTech hum eliminator as well. Doesn't matter if the guitar is plugged in or not. Also re-soldered the speaker leads. It is really starting to take away my enjoyment of this amazing little amp. The noise is on all channels equally and gets quiet as the volume knob is turned down.

Any ideas? Suggestions?

 

[MrRFasters]

I'm a lucky guy.
I started this subject and I got luchky: My Mesa started doing this onde day and the fun of it is: just another day it stopped with it also.

It looks like a loose tube that's in doubt wether being loose or fitted. I'm not such a travelling man, so I guess I can live with it for now ... :mrgreen:

 

[Wolfboy1]

Thanks for the reply, I will check my tubes again.

 

[Wolfboy1]

I am still having this problem and not sure why. I think after my gig Saturday night I'm taking it in to the shop and see what they tell me.

 

[Amp repair]

Hello I think this could help, I am an amp repairer from spain. They have bring me one off this amps whith exactli this problem. Efectiveli first choice change tubes with no results. When I opened this i found the problem, both midle cables from the gain pot goes very closse to the relays and also there is one problem with the jumper cable ho is up the relays, Im gone to try some things to solve it, I will tell you what goes on, bu I think That it is a design problem that apears in some amps for any reason whith nothing diferent. This amp has already ben sent to mesa to repair it with no results. I will try it and I will tell you what hapens.

 

[Newysurfer]

Hello I think this could help, I am an amp repairer from spain. They have bring me one off this amps whith exactli this problem. Efectiveli first choice change tubes with no results. When I opened this i found the problem, both midle cables from the gain pot goes very closse to the relays and also there is one problem with the jumper cable ho is up the relays, Im gone to try some things to solve it, I will tell you what goes on, bu I think That it is a design problem that apears in some amps for any reason whith nothing diferent. This amp has already ben sent to mesa to repair it with no results. I will try it and I will tell you what hapens.

right then - well how come I've been on this forum for 3 years and this is the very 1st time I've ever heard of this problem with a 5:25.
No-one else has reported similar on any other forum I've seen either hehehe

 

[Wolfboy1]

I am curious to hear your results "Amp Repair" as I still have this problem and would glady try and fix it myself if possible. So please keep us informed and THANK-YOU so much for your reply.

On a side note, I had the pleasure of living in Spain for about 8 months in the 1980s, I loved your country! Very friendly people in Jerez and Cadiz. Plus....in all my travels the Al Hambra is my favorite place to visit.

 

[Wolfboy1]

This issue seems to be getting worse. Seems to start after about 20-30 minutes of playing then if I shut my amp off for 10sec or so it goes away for a short while. As I mentioned...all new Mesa tubes and reset them them again after changing....unless some one has any more ideas I guess it's back to the dealer? Thanks.

 

[Wolfboy1]

Got an appointment to take it in Saturday. A bit of a drive but still under warranty and taking it to an authorized dealer. He had never heard of the problem but assurd me he would figure it out if he had to call George at Mesa.

So, rare as this problem might be, I will post what I eventually find out. I just love this amp and want to get it healthy again.

 

[Nubbs]

I have a 5:25 with 10". I had a similar problem. It was a preamp tube. MY local guy suggested swapping v1 with another preamp in the stack. I did and it worked for a while. Then I had a microphonic tube that would ring after playing a high note in the red channel. I then replaced all the tube with a matched set of Mesa's.

No more problems.


Nubbs

 

[Wolfboy1]

Thanks for the info, I hope it is something simple like that. When I went to his shop he had a mint Fender Champion 600 he had fixed that some one had given him (faulty resistor). Sounded great said I could take it as a loner amp or if I wanted to buy it....$55.00. It's mine cha-ching

 

[Wolfboy1]

Well 3 weeks later the tech threw in the towel and is sending it back to Mesa. I was worried he wouldn't be able to duplicate the problem but he did. Sometimes he had to leave it on as long as three hours before it would start crackling so he could trouble shoot but no luck. Apparently he had a lot of time in it under warranty and was losing money with it so I told him it was fine to send to Mesa. The guy has several patents even and couldn't figure out the issue. He is sending all his notes in with the amp and thinks Mesa will probably just send me a new amp.....so still in the dark.

 

[Wolfboy1]

So....September 26th I took it to the shop and today December 2nd, I finally got it back. I didn't get to play it tonight but will be on it this weekend. They had a hard time duplicating the problem at Mesa (but they did) and then a hard time locating the problem. Turned out a capacitor was installed backward on the circuit board in the contour circuit path. When hand assembled I guess this can happen easily the tech told me. I am happy to have it back, hope it checks out 5x5 this weekend when I put it under duress :wink:

By the way I would like to put a plug in for Pete Wickham of Wickham Audio. Super nice person to deal with and very helpful. Made several calls to Mesa for me and kept me updated on progress. He is in central Ohio at 1-740-398-0548 and can be found at

http://www.wickhamaudio.com

I would not hesitate to take my gear to him to repair.