Mesa mk IV question about spax7 and suspicious screws

Hi,
i bought new one mesa mk iv since 2008...and today i decide to change
tube... so i have two question:

1 - I have spax7 and I have problem with v1 tube because there is aluminum cover on this position and spax7 also have black shield and it is not have enough space for tube inside...
Should i take of black shield from tube or turn off two Little screws and take off aluminum cover from amp?

2- I have one screws in very suspicius condition...since i bought amp this screws look like is not twist on to the end...? there is link with pictures

http://s1089.photobucket.com/user/zrkrlk/library/?view=recent&page=1

Hello,

The rubber coating on the SPAX7 is a standard feature of this tube. And it is the recommended tube for the V1 position of the Mark IV. So you should leave it intact.

The metal tube shield is also a standard feature for the V1 position and should be installed (assuming that you wish to use the amp as it was designed). The tube shield should be able to fit over the SPAX7 without forcing it.

On my Mark IVa combo, the tube shield was a "Elco TS103U03". It is roughly 60 mm (2.25 inches) in height and internal diameter of about 24.24 mm (just under 1 inch).

You may wish to check the dimensions of the tube shield that you have. A common error is use one that is too short. Using excessive force with such a shield will likely result in a shattered SPAX7 :-(

The "suspicious screw" in the photograph is actually a bolt that tensions the large flat surface of the metal chassis. (I assume that its function is to dampen vibrations.) My model does not have this feature (I just checked). But a similar bolt is present on my Express 5:50 combo (not the "plus" model).

Be careful not to over-tighten it, because it will gouge a hole on the inside of the cabinet. Also, it's a good idea to loosen this bolt before removing the chassis.

I hope that helps. Enjoy your Mark IV!

Thanks...!!

I also contact on mail mesa boogie customer service, and they giv me explanation about chaises screw...
And aluminum cover is definitely too Small for spax7... they Say that i must to take off black shield or aluminum cover... and i decide to take off aluminum cover because it is very easy to do this, and if i take of black shield I can not fix back...
there is a link with picture of aliminium cover and spax7 together.

http://s1089.photobucket.com/user/zrkrlk/media/Mobile%20Uploads/image.jpeg.html?o=0


Sorry for my english

Regarding the chassis screw, can you cut & paste the answer from the Mesa Boogie email?

Now to the SPAX7 ... with this latest series of pictures, I definitely understand the problem better.

The portion of the metal shield shown, is the base of the tube shield. In my Mark IVa, the base is fastened to the chassis with 2 short screws. When the SPAX7 is removed, the base is supposed to remain with the chassis. When the SPAX7 is re-inserted, the top portion of the tube shield is placed over the tube and over the base, then turned approximately a 1/4 turn to latch the top and the base together. Or at least that is how it is designed to work.

How did you remove the base of tube shield? Wasn't it fastened to the chassis? Are there 2 screw holes in the chassis where the base could be fastened? If not, then it is possible that your model wasn't designed to use a tube shield.