Proud New Owner

[avi8r2005]

Hey everybody. I'm pretty new here, but been lurking in the shadows for a week now since I aquired my Single Rec 50. Pretty smoking amp for 50 watts, great tones, IMO. I went from a Line 6 Flextone III to a Rocktron Voodu Valve now to this, all within a matter of 7 months. I'm a tone junkie. THis is my first Mesa and soon to be accompanied by a Dual Rec. However the DR i'm buying has some issues according to the owner, which hopefully someone has some tips on. Apparently it's blowing the fuse right as the power switch is flipped on. He seems to think it's a bad power transformer, however the Mesa rep I spoke to thinks it's something less serious than that, such as a screen filter (not sure if I got the terminology correct). But any tips on how to trouble-shoot it and get to the bottom of this would be greatly appreciated. The amp is such a screaming price I couldn't pass on it.

Thanks.
Equipment:
ESP KH-2 NTB, made around 1997
Mesa Boogie Single Rectifier 50
Rocktron Tri-Wah
Recto Std. 2x12 Cabinet

 

[jamme61]

are you ok with pulling the chasis out? You can get killed if your not sure bring it to a tech. If you know what to do and how to drain the caps, then you could pull the chasis and just make sure none of the resistors have fried by the power tubes. Also how old are the power tubes? if you have a bad power tube it will blow a fuse. Again don't electrocute yourself, if your not sure then leave it alone.

 

[domct203]

are you ok with pulling the chasis out? You can get killed if your not sure bring it to a tech. If you know what to do and how to drain the caps, then you could pull the chasis and just make sure none of the resistors have fried by the power tubes. Also how old are the power tubes? if you have a bad power tube it will blow a fuse. Again don't electrocute yourself, if your not sure then leave it alone.

+1000. There are some high voltages inside.

This could be something a simple as a bad power or rectifier tube. When you get a used amp a complete re-tube (at least power and rectifier) is always a good idea anyway. If you re-tube and the problem goes away, great. If not, a screen grid resistor replacement is not a big $$ item. Start looking for techs now just incase.

And WELCOME !!

Dom

 

[avi8r2005]

Thanks for the pointers. I plan to change all the tubes when I get it although he put new ones in recently, but not Mesa Stock. As far as fixing it myself, other than change the tubes and fuses, I don't plan to do that myself. However how can I isolate the screen resistor? I'm still new to all of the tube amp terminology, been a solid-state and modeling guy for too long.

Much appreciated.

 

[clutch71]

Thanks for the pointers. I plan to change all the tubes when I get it although he put new ones in recently, but not Mesa Stock. As far as fixing it myself, other than change the tubes and fuses, I don't plan to do that myself. However how can I isolate the screen resistor? I'm still new to all of the tube amp terminology, been a solid-state and modeling guy for too long.

Much appreciated.

When you get the amp and if you use the caution above. Pull the chasis and visually inspect the board. The dangerous part that you don't want to touch are the blue things that look like D cell batteries. I forget their proper name, but just don't touch anything on the board itself to be safe. I did it and I'm still here.

You can visually inspect the board to see if there anything that looks fried or burnt. Of course it could be on the bottom of the circuit board but it's a good start. if you don't see anything obvious and you re-tube, there is the possibility that you blow a tube if the fuse doesn't pop first.

With tube amps always, always, always make sure you have a proper speaker load plugged into the correct ohmage for your cabinet and the bias switch is set for the tubes your using ie EL34 or 6L6.

Good luck and welcome to the board!

 

[eventide_awakening]

+1 on always plugging speakers up

you don't want to deal with the after effects

 

[merkinball94]

I dont have this problem so I'm not going to try it, but I noticed several people said not to touch the blue battery looking thing - is that only with the amp plugged in that it's dangerous? Or does that device retain power even after unplugged? I probably dont know how it works, but I would think if left unplugged long enough it would lose charge?

 

[Boogiebabies]

I dont have this problem so I'm not going to try it, but I noticed several people said not to touch the blue battery looking thing - is that only with the amp plugged in that it's dangerous? Or does that device retain power even after unplugged? I probably dont know how it works, but I would think if left unplugged long enough it would lose charge?

They can store a charge for a very long time, even unplugged. The safest way to discharge them is with a simple 10W resistor with alligator clips or probes at both ends. Connect one end to the chassis and then use the probe on the + end of the cap to bleed the stored voltage. I use a 10W 100 ohm resistor. The speaker can discharge the caps, but it is not a fool proof method. Sometimes if you turn an amp on and then off after plating a minute you will actually hear the caps discharge through the speaker. It sounds like a groan or flatulence, but the caps when read with a meter can still hold enough voltage for a good shock. Mesa's and Boogie's tend to discharge themselves very quickly after shutdown, but this is no guarantee. Always unplug the amp and steer clear of the caps until you know they are discharged or read less than 6V or so.

 

[merkinball94]

I dont have this problem so I'm not going to try it, but I noticed several people said not to touch the blue battery looking thing - is that only with the amp plugged in that it's dangerous? Or does that device retain power even after unplugged? I probably dont know how it works, but I would think if left unplugged long enough it would lose charge?

They can store a charge for a very long time, even unplugged. The safest way to discharge them is with a simple 10W resistor with alligator clips or probes at both ends. Connect one end to the chassis and then use the probe on the + end of the cap to bleed the stored voltage. I use a 10W 100 ohm resistor. The speaker can discharge the caps, but it is not a fool proof method. Sometimes if you turn an amp on and then off after plating a minute you will actually hear the caps discharge through the speaker. It sounds like a groan or flatulence, but the caps when read with a meter can still hold enough voltage for a good shock. Mesa's and Boogie's tend to discharge themselves very quickly after shutdown, but this is no guarantee. Always unplug the amp and steer clear of the caps until you know they are discharged or read less than 6V or so.

Thanks for all the info. How long is long on the average? Hours? Weeks? Months?

 

[Boogiebabies]

I never play averages. I measure with a meter or automatically drain them. From personal experience, it is not something you want to feel.

 

[merkinball94]

I never play averages. I measure with a meter or automatically drain them. From personal experience, it is not something you want to feel.

Right, I understand. I was just curious as to how long the charge lasted.

 

[clutch71]

....I did it and I'm still here.

Just wanted to clarify that I pulled the chasis out carefully and did not touch anything on the board.