Subway Blues hum problem - when did they sort it out?

[Divrack]

after two trips back to the techs shop I finally just sold mine it was still way too loud for my liking. I was shocked the guy bought it Next time ill go back to the subway rocket which i loved

 

[badboybubby]

I have an original Subway Blues purchased new in '94. I've been living with the "hum" problem for all these years and finally decided to have something done. Mesa emailed me this:

Which I believe is the same as this image which was posted here earlier:

I provided these instructions to my tech, who is an authorized Mesa repair tech. He initially did the mod per instructions but the results were that there was hardly any output from the amp, so he contacted George at Mesa Boogie, who claimed that these instructions were wrong and walked him through the correct procedure.

When I brought the amp home and fired it up, I find that the "hum" is gone, but there is a bizarre issue now with the tone controls. At first I thought that the 'bass' control was totally disengaged so I brought it back to the tech. Upon further testing, all 3 tone controls do work, but their range is now extremely minimal. If you turn all the tone controls to zero, there is no output at all, and if you then turn each up individually one at at time you can tell that they are working......BUT...as I said very minimally. For instance, if you turn the bass to '10' you would expect the sound to be very muddy, but now it is hard to hear a difference between '1' and '10'. Likewise with the mid and treble.

The Mesa Boogie tech, George, will be gone for over a week. Until he returns and we can speak with him directly, does anyone have any input on this?

Thanks.

 

[Ken j]

Yes. I have the hum mod sent to me from Mesa and it shows replacing a cap with a different value. PM me your email address and I will send you what I have. The mod is dated April 1998.

 

[badboybubby]

The mod that was sent to me and done by my tech is the "mojo bypass mod". This bypasses and eliminates the effects loop. I sent photos of the board to the Mesa tech (George) and he verified that my tech did it correctly.

The hum is gone, but the amp is now voiced differently than it used to be--It is now much brighter sounding and the tone controls do not have as much effect as they used to. I've been playing with it and tweaking the controls to see if it is acceptable. If not, I will reverse the mod and live with the hum.

Has anyone else who has done this mod experienced this? I was originally told by the Mesa tech that the only consequence of this mod was that the effects loop would be disabled. Obviously not the case.

 

[Ken j]

The mod I have is for the hum. It does not bypass the effects loop. It is a PDF file otherwise I would just post it on Photobucket and link it here.

 

[goldenGeek]

...

When I brought the amp home and fired it up, I find that the "hum" is gone, but there is a bizarre issue now with the tone controls. At first I thought that the 'bass' control was totally disengaged so I brought it back to the tech. Upon further testing, all 3 tone controls do work, but their range is now extremely minimal. If you turn all the tone controls to zero, there is no output at all, and if you then turn each up individually one at at time you can tell that they are working......BUT...as I said very minimally. For instance, if you turn the bass to '10' you would expect the sound to be very muddy, but now it is hard to hear a difference between '1' and '10'. Likewise with the mid and treble.
...

I know this is a necro-bump, but did you ever find out what happened to the tone-controls? I have mocked around in mine this week to get rid of some bad noise and now it also has this weird "error" where the tone controls does almost nothing. The treble acts more or less as a gain control and the others has an almost un-noticeable function.