Weird Mesa Heartbreaker screw

[Voxbox]

Hello,


I have a Mesa Heartbreaker in for repair and re-valve.


found two faults - one of the solder joints on the speaker jack plug was poorly done and had come adrift, thought there was still sound coming out of the speakers, albeit very lifeless.
The second issue was that there was 3 Mesa 6L6s and and one EH 6L6, which looked like the Mesas. Bias was 25mA. All voltages correct


Once the jack joint was remade it sounded loads better.
changing the valves to Svetlana Winged Cs made an improvement too. Bias at 30mA.


Anyway, the point of this missive is to find out what on earth this screw is doing in the chassis, see pic.


All it does is press into the screening panel on the cabinet above the chassis. I cant work out the point of it!


Any ideas?

[sluckey]

Probably ensures that the screen on top has a good electrical connection to the chassis in order to make a good shield for the open side of the chassis.

[Voxbox]

Thanks Sluckey, I did consider that. It's a bit iffy really. Once it's been screwed in a few times the foil on the cab is torn.
There is also a copper-like bent strip on one end of the chassis that I presume is fulfilling the same function.
The rest of the amp is pretty well built but that aspect of it is a bit Heath Robinson.


(I don't want to get into a discussion about pcbs with tiny lands though!  )


Cheers, VB

[Platefire]

I've got a MB Rocket 440 and it  has one of those screws. According to attached link from Sweetwater, it is to put tension on cab to remove any rattles caused from vibrations from the speakers. Here is a link:

https://www.sweetwater.com/sweetcare/articles/my-mesa-boo

When you pull the chassis, you need to take the tension off first, then re-adjust it
when chassis goes back in

[Voxbox]

Ah that explains it. Would have been good to know before taking the chassis out!🙄😁
Cheers, VB

[Latole]

From Platefire

Link can be removed over time. To keep information accessible :

My Mesa Boogie has a loose screw
Article #1762194 Updated on Apr 13, 2020 at 6:30 PM

Occasionally we get this question in the Sweetwater service department: “A big screw is sticking up behind the tubes on my Mesa Boogie amp. What is this? Is something coming apart? “

This is known as the chassis tension screw (or bolt) . It it used to stop rattles in the chassis from acoustic vibration in the cabinet due to the powerful speakers.

It is a long bolt/screw that reaches all the way to the wooden cabinet above to cause a dampening effect to vibrations in the metal. It normally does stick out and IS NOT tightened down very much. Only tighten it until it makes light resistance against the top of the amplifier.




 

[sluckey]

Link can be removed over time. To keep information accessible :

That info will probably last longer at Sweetwater than it will on this forum. Hoffman periodically purges the forum of old images to make room for new discussions. He does not have unlimited cloud space.

[Latole]

Link can be removed over time. To keep information accessible :

That info will probably last longer at Sweetwater than it will on this forum. Hoffman periodically purges the forum of old images to make room for new discussions. He does not have unlimited cloud space.

You are right , pictures need lots of space