help with mesa 50/50

Chacoop · Not So Newbie Joined: 17 Mar 2007 Posts: 5

Hello, I have been working on a small rack setup after playing a friend's..and so I ordered the preamp and conditioner first. I ordered the mesa 50/50 from ebay..and for some reason when I got it it had kt66 tubes in it? anyway..last night I played it and the amp functioned as it should, but when I turned it on today the volume gradually dropped until it is almost completely inaudible. What could be the problem?

tw001_tw · Posted: Sat Jul 21, 2007 7:23 am Post subject:

This could be a lot of things - from just a loose tube that's not making
a good connection in the socket to a bad Output transformer. And a
few things in between. First, reseat all of the tubes (be careful and I
expect you to know general amp safety before trying this) Are you
100% sure the speaker impedance is what the power amp was expecting?

If you are technically/electrically inclined, there is more that you can do,
but if not, you're best bet is to take it to an amp tech. I have heard one
output transformer go bad..... and you described it. Volume dropped, then
pretty much nothing. Turned the amp off - then back on - and it worked
for maybe 10 seconds? then volume decreased. Turned it off, then back
on and nothing. Sound familiar? I hope not.

Chacoop · Not So Newbie Joined: 17 Mar 2007 Posts: 5

The thing is it worked the night that I got it fine. The next day it started screwing up as soon as I turned it on. I'm using it on 8ohms stereo..and I made sure the tubes were tight. There WAS one loose after I checked it out..but they're snug now. It still is doing the same thing though. Thanks for your help though..I guess a tech wouldn't be a bad idea Crying or Very sad

.

MikeM · Posted: Sat Jul 21, 2007 11:43 pm Post subject:

Another possibility is a shorted power tube. I fixed a buddy's old Gibson amp for him and his was doing something similar. Turned it on, some sound for a while and then gradually......nothing.
I would hope your amp would have a fuse to protect the OT from such things? I'm not real familiar with the 50/50.

Chacoop · Not So Newbie Joined: 17 Mar 2007 Posts: 5

it has a fuse but I'm sort of a noob to electronics. The tubes all light up fine..could there still be a bad one that way?

MikeM · Posted: Thu Jul 26, 2007 7:32 pm Post subject:

You can't tell by looking at them if the tubes are ok. The light you see is from the heater(s) elements in the tube.