Mark III and possibly other boogies Reverb Hum Fix!!!

[jedmon01]

This mod worked on my Boogie Mark I reissue.
I can hardly hear any hum now the tank has been turned through 180 degrees.
Why hasn't Mesa sussed this out years ago ???
John

 

[dgr888]

Thanks jedmon for helping to keep this topic upfront so others can benefit from this fix... it probably would have cost them a bunch to recall all the amps they have sold!!! And yours is a Reissue and they still haven't got a clue!!!
As a side note one time I counted the LDR's they used for switching and various other functions in the Mark 4. If I remember correctly it was between 25 and 30!! So much for being ALL tube amps!!!!

 

[jpdennis]

...The hum in the reverb is caused by the power transformer because the input of the reverb tank is too close. The simple fix is to turn the tank around so the input transformer does not pick up the hum created by the power trans...

O.K. I am looking at my Mark III schematic and following this thread. The Grey shielded cable is the one from the reverb input at the amp side (front-most RCA female connector on the amp) and connects to the output female RCA jack on the tank side per the schematic and my amp's physical connection. The white single wire is the one from the amp's output which then goes to the tanks input. So am I correct to assume that I want the tank's output jack to be farthest from the amp's power transformer?

I only ask because I want to make sure I am fully understanding.

Thanks for any clarification with this.

Dennis

 

[dgr888]

The wires stay as connected on the amp and tank as they are. Just turn the tank around which puts the input with the shield under the output trans. instead of the power trans. That simple...

 

[jpdennis]

The wires stay as connected on the amp and tank as they are. Just turn the tank around which puts the input with the shield under the output trans. instead of the power trans. That simple...

And it was that simple. This definitely quieted the reverb hum to ... yep, can't hear it. 8)

Thanks, dgr888

Dennis

 

[dgr888]

Thanks Dennis and I am happy you now have a much quieter amp. I see yours has the initials in it of one of the top dogs at "Mesa Engineering" so what burns my a@# is with ALL those "Great Ears" they didn't hear this annoying hum and take the time to track it down. Probably countless thousand's of these are still out here. Shame on "Mesa Engineering...

 

[jpdennis]

... with ALL those "Great Ears" they didn't hear this annoying hum and take the time to track it down...

dgr888,

FYI -

I was in Petaluma Thursday and I dropped my Mark III off for other reasons and spoke to Mike Bendinelli while I was there, since he is the one who will go over it. He said that there is a "service update or bulletin" for the reverb he does whenever he gets a Mark III in. I didn't ask if it applied to any of the other Mark I or II series. However, what he does was over my head; something about inconsistent power voltage or something when returning from standby. I will post the results of everything with pictures when I get it back in the thread I started. The thread I started is here - http://forum.grailtone.com/viewtopic.php?f=27&t=57819 -

Just thought it was interesting and maybe you already know about this mod.

On another note, I did tell him about rotating the reverb tank. He said the fan would make a hum as well. I told him it did but I mounted the fan the same way I mounted a fan in my .50 Caliber combo under the PT on the other side as well when I did the rotation of the tank. I will include the "chassis only" AND the "once mounted" shots in my thread when it returns.

Dennis

 

[dgr888]

Thanks Dennis and keep us updated on this. In all the amps I have done I didn't remount the fan so I don't know if it really makes much difference. I have a 2c but I don't run the fan as I just leave it unplugged. I do know by turning these tanks around it really quiets the amps. If remounting the fan works I say go for it!!! Whatever it takes to make these studioworthy as should have been done in the first place....In a previous post
by jedmon01 he has a Mark 1"REISSUE" and had to turn the tank??? Go figure even after all these years it still goes on............

 

[dgr888]

Members let everyone one know how this worked on your Mark 3's etc. and any other models. Over 1200 views so let's keep the other members informed as that's what these boards are for....

 

[jpdennis]

I did this in my Heartbreaker as well. I forgot to mention that in my new post on it - I just got it back from the shop Tuesday. Didn't notice a difference but the PT is a hefty Mercury magnetics one and the distance from the PT to the tank is not as boxed in my the small combos such as my Mark III and my .50 Caliber. Still I will use this method regardless.

Dennis

 

[boogietone]

Tried this mod on my DC-10 combo but the cables were too short.

 

[jpdennis]

Tried this mod on my DC-10 combo but the cables were too short.

I bought some cables at radio shack that allowed me to do this. I have only had to replace the shielded grey cable. The white wire has been longer then I need so I just use it and re-route it as needed.

Dennis

 

[dgr888]

Thanks for the replies to this and please keep posting letting other members know of how it does with the other models besides the Mark series.

 

[Val666]

I felt like tinkering today and tried this (in my Mark III green stripe) it definitely reduces hum

I had to remove the fan (which I never use anyway) to gain access to the reverb tank. If I could, I'd remove the reverb completely but I'm not very good with electronics so...

Anyway, I unscrewed the back panel (I had to unscrew the fan to remove the panel completely) then I cut the clips which were holding the reverb's cables in place and switched it around

Put everything back together again and the hum was reduced.

Basically, it works.

 

[dgr888]

Thanks Val for the response. You and other members can finally enjoy these amps without the hum. I'm glad for the responses to help keep this thread alive as there are so many of theses amps out there with this problem and it is fairly a simple fix to make. Boogie won't fix them so we will.... Keep them coming...

 

[Val666]

Thanks Val for the response. You and other members can finally enjoy these amps without the hum. I'm glad for the responses to help keep this thread alive as there are so many of theses amps out there with this problem and it is fairly a simple fix to make. Boogie won't fix them so we will.... Keep them coming...

It's cool man, hey thank's for sharing the advice!

I got my Mark III recently (used) and just figured, hey it's happening because it's second hand! Your simple tweak cures the problem!

 

[dgr888]

Thanks again Val.....Most who have these did not/do not realize that these came new like this and have always thought (or been told) the hum/noise was just the way it was designed,(Correct but designed wrong). I've been fixing this "problem " since the 80's for my customers which should have been fixed right at the factory by Boogie at their expense... Obviously I cannot fix all that are out there so I figured I'd share it with the members. Now if I could just get a dollar for every amp from Boogie for finding and correcting THEIR problem I could get rich. Fat chance of that!!!!

 

[dgr888]

Bump this back up to the top for new users to see...this mod works Ya'll....cures a lot of hum/buzz generated in these amps....

 

[Markedman]

Bump - should be of interest to many.