Mark III chassis question

[jjblacksheep]

I still haven't had much time to play on my new head. Yesterday I turned it over to look at something on the back and heard something loose in the chassis. Only when you turn it fairly quick but there is something loose in there near the power cord. Well, since this is my first Boogie head I started looking to see how to take the chassis out to see if I can find the source of the sound although the amp seems to be working perfectly. I then notice that the 2 support brackets in the rear of the head on each side are not screwed to the chassis. In fact there is a good 1/4" to 1/2" space from the bracket to the chassis. I now wonder if it has been tinkered with.....the brackets are level but a damn good ways from the chassis. Anyone else have something like this.....or maybe the brackets were installed too low and never bolted to the chassis from the factory. Also if anyone can help on the easiest way to slide the chassis out so I can look in there, I would appreciate it.

 

[MrMarkIII]

I believe those brackets are really designed to support the chassis during removal, not attach it to the cabinet. If you loosen the chassis bolts, the chassis will lower down onto the brackets.
I think.

 

[jjblacksheep]

Hmmmm...ok. It just looks like there are corresponding screw holes in the chassis that line up. Thanks for the help, just curious. I'm going to try to get teh chassis out today to see what is loose in there and see how everything looks. I haven't had a chance to look over it very well so not even sure exactly how the chassis is bolted, but I'll figure it out. I know some amps are hell in that regards, here's hoping this one is not

 

[silentrage]

Dude, I get the same thing in my blue stripe short head, let me know what you figure out.

 

[jjblacksheep]

Ha really? What it sounds like is....not something rolling around but something attached, but not solidly so that when you tip the amp, it "lifts" then when you tip the amp back over it falls back into place. If you tip the amp slow, you don't hear it. I'm sure it's nothing.............but I have to check it out.

 

[silentrage]

That's exactly it, and it feels like something heavy because it seems to shift the centre of gravity of the amp with it.

 

[jjblacksheep]

Thanks a ton. I eyed the 4 screws yesterday and was hoping that was it. Very simple. Thanks for the tip on the fan, probably woulda missed that and had some type of tug of war. With luck I can get to it this evening and see what's in there rattling and what kind of shape she's in. Don't worry.....I got popped by a Carvin power amp a few years ago :shock: . I bleed em dry now and am extra careful

 

[jjblacksheep]

Ok, opened her up although there was no fan cord. That rattling noise is a separate small board with 2 huge caps on it (much bigger than those on the main board--I didn't have anything to write down the values)......and there's no place to put it so it just kinda sits at an angle where it can. That's what you hear moving around. Seems odd to me. But everything in there is CLEAN, not even dusty. I was ecstatic.

 

[Old BF Shred]

Whoa....that sounds odd to me. Every Mesa (or just about any other brand) amp I have seen has all circuit boards anchored to something......often with simple, plastic standoffs; sometimes with screws on threaded posts.

However, I've never owned a Mk 3 so it could be an exception. Just surprises me though, because common fabrication standards dictate that the board should be secured. Is it possible there were plastic standoffs that crumbled with age and heat? (quite common in old electronic equipment). Perhaps some empty chassis holes in the vicinity that are evidence to that? :?:

A call to Mesa to verify might be worth the phone charges. Larger size capacitors would generally indicate power supply filters. You do not want them floating around the inside of your amp. :shock:

Good luck with that!

 

[MrMarkIII]

Note: The brackets you reference are for support only while taking the chassis in and out of the headshell. they are not meant to be in contact with the chassis once it's mounted in the headshell.

Thanks.

 

[jjblacksheep]

There are plastic standoffs but with the size of the caps, they would stick out of the chassis way too far for you to get it into the head. And you can't have them lowered because of the lack of space with other stuff all around it (it's right behind the Standby switch). So yeah, it just kinda lays there at an angle to fit. And yes I'm pretty certain they are power supply filters. With where they are........................I don't see how they can be mounted securely at all. No room. Again, odd to me. Maybe someone else can chime in?

 

[boogiemon]

my MIII combo has no *floating* components, & it's been bounced around quite a bit.

There are plastic standoffs but with the size of the caps, they would stick out of the chassis way too far for you to get it into the head. And you can't have them lowered because of the lack of space with other stuff all around it (it's right behind the Standby switch). So yeah, it just kinda lays there at an angle to fit. And yes I'm pretty certain they are power supply filters. With where they are........................I don't see how they can be mounted securely at all. No room. Again, odd to me. Maybe someone else can chime in?

 

[jjblacksheep]

Some kind of mod??? Where it's wired, it has to float, there is no room for it to be mounted. Funky stuff. :?

 

[jjblacksheep]

Boogiemon (or anyone else) do you have that separate board w/ caps mounted behind the standby switch?

 

[boogiemon]

it is mounted, i just don't remember where exactly. i'll take another look when i get a chance.

Boogiemon (or anyone else) do you have that separate board w/ caps mounted behind the standby switch?

 

[JOEY B.]

Ok, opened her up although there was no fan cord. That rattling noise is a separate small board with 2 huge caps on it (much bigger than those on the main board--I didn't have anything to write down the values)......and there's no place to put it so it just kinda sits at an angle where it can. That's what you hear moving around. Seems odd to me. But everything in there is CLEAN, not even dusty. I was ecstatic.

That is the filter cap board. There are actually 4 large capacitors on it, 2 above and 2 below the circuit board. The main board that you speak of is the preamp board. 8)

 

[jjblacksheep]

Thanks....mine just has 2 on top, none on bottom (60W fixed).