# Mesa/Boogie 50:50



## metrick (Jun 16, 2015)

I found my lost fuse cap. Thank for all reply. Any way what I thought was problems with tubes, so i went to L&M and purchased all new tubes 4 x 6L6 & 3 x 12AX7A Mesa Boogie Tubes. Cost over 200$. Ouch! 
Now with new tubes replaced, and after a few minutes of playing, the fuse burned again. The 6L6 tube near the fan glowed brightest, the rest of the 6L6 tubes look to glow at the same Intensity and lot dimmer than one near the fan. 
Any diagnostic that i can do or what could be the problem? Thank in advance.


----------



## Stratin2traynor (Sep 27, 2006)

Have you called Mesa Boogie? I hear they offer really good support. I haven't tried it myself, but everyone I've spoken to were happy after they called.


----------



## keto (May 23, 2006)

SWAG - scientific wild assed guess - burnt resistor somewhere near the bias circuit. Take a look at the board and see if you can see any
a) broken solder joints
b) burnt or broken looking resistors


----------



## metrick (Jun 16, 2015)

metrick said:


> I found my lost fuse cap. Thank for all reply. Any way what I thought was problems with tubes, so i went to L&M and purchased all new tubes 4 x 6L6 & 3 x 12AX7A Mesa Boogie Tubes. Cost over 200$. Ouch!
> Now with new tubes replaced, and after a few minutes of playing, the fuse burned again. The 6L6 tube near the fan glowed brightest, the rest of the 6L6 tubes look to glow at the same Intensity and lot dimmer than one near the fan.
> Any diagnostic that i can do or what could be the problem? Thank in advance.










Here is a image if the tubes glows for comparison. I'm too afraid to keep it on for long time. You can see that the tube near the fan glow very strong.


----------



## bigboki (Apr 16, 2015)

yeah, definitely don't keep it running like that.
All tubes should glow about the same intensity.

Is this on standby, or when fully powered?

Check with Mesa first and then go from there

yours Bojan


----------



## jb welder (Sep 14, 2010)

Don't run the amp with the power tubes installed until the problem is fixed. You will damage them, the one that lit up may already be damaged depending how long it was run like that.
You need to take it to a shop to get fixed, or repair the bias circuit. You can check the bias voltage at pin 5 of the power tube sockets, which can be done without removing the chassis.


----------



## metrick (Jun 16, 2015)

bigboki said:


> yeah, definitely don't keep it running like that.
> All tubes should glow about the same intensity.
> 
> Is this on standby, or when fully powered?
> ...


On full power and only on for few seconds. Hard to see but the near fan tube is already had the burn. On Stand by, all tubed glow about the same. Thank you all.


----------

