How do I open a Fishman Loudbox?

[Albert Kreuzer]

Got a Fishman Loudbox acoustic amp on the bench. It is working, the only issue is a scratchy volume pot. Nothing a drop of Deoxit wouldn't fix.
But I can't find a way to get to the pots. I have removed about every accessible screw, no success.
This thing seems to be locked from inside (so there must be somebody in there, right?). Above the controls I can see two bolts or locking bars (see pic).

Has anyone opened one of these yet and can help me?

Thanks
Albert

[52 Bill]

Can't help with the removal, unless the baffle comes out. How about the handle screws?

Try squirting the Deoxit from the front where the pot shaft passes through the mounting bushing. It will work its way through to the insides and will give you at least a temporary fix.

[Albert Kreuzer]

Can't help with the removal, unless the baffle comes out. How about the handle screws?

Removed the handle. Removed the corners. No joy. Baffle is glued in. Removed the speaker. Everything sealed inside, no access to the electronisc.

Try squirting the Deoxit from the front where the pot shaft passes through the mounting bushing. It will work its way through to the insides and will give you at least a temporary fix.

Yes, probably the only way for now.

Thanks,
Albert

[Jazz P Bass]

I had one of these where the chassis was put in when the Tolex glue was still wet & it smeared out & got on the chassis.
Guess what happened when it dried?

[Albert Kreuzer]

It glued the chassis in place?
How did you get it out?

[J M Fahey]

Try to slip a thin blade of metal (the typical 30cm stainless steel rule in cm and inches is great for that) between the chassis top and the cabinet top inside face, all the way full right to full left; the same in the back, same between chassis bottom from the front and back.
Once you have only "air" between the chassis and surrounding surfaces, it *should* slide out.
If any of that space is filled with glue, you know what to do.
Please post a back panel picture too, and put a lamp on the back, try to catch its shine on front.
Lighting a few black and red candles can also help.

[Albert Kreuzer]

Try to slip a thin blade of metal (the typical 30cm stainless steel rule in cm and inches is great for that) between the chassis top and the cabinet top inside face, all the way full right to full left; the same in the back, same between chassis bottom from the front and back.
Once you have only "air" between the chassis and surrounding surfaces, it *should* slide out.

Have tried that already, no luck. The bars won't move, neither sideways nor front to back.
However, my steel rule is marked in cm only - maybe inches would do better.

If any of that space is filled with glue, you know what to do.
Please post a back panel picture too, and put a lamp on the back, try to catch its shine on front.

No glue. I can move the chassis by fractions of a mm.
The rear panel is fitted with screws from the inside (!), can't see them on the pic. Also no see-through to the front panel except a tiny slot on the top (which let me discover the front locks).

Lighting a few black and red candles can also help.

Yes, makes perfect sense
I also was thinking about a trying a sledgehammer.

Thanks,
Albert

[J M Fahey]

Those unexplained screw holes , 4 in the front and 2 in the back , holding an external grey painted "shell" to silver inside chassis, makes me think that said shell(s) can be pulled, maybe they are still held by jack nuts at this point and nothing else.
Try to reasonably wiggle them to find the center of rotation, which I guess might be said nuts, and take them out.
You might be able to pull the grey panels and probably find hidden screw heads under them, bolting the main chassis to the wood.
There's no other way.
Explore it, and good luck.

[Albert Kreuzer]

BINGO!
Juan, I owe you a beer!

That was it. Hidden screws behind the faceplate. The rest was (comparatively) easy.
Soaked the offending pot in Deoxit, case closed.

Thanks again!
Albert

[J M Fahey]

Juan, I owe you a beer!

Fine with me.
Just ask Gretchen to bring it, will you?

For a purely scientific interest, of course !!
I'd also love to see what the front panel hides

Back to your Loudbox, your picture creates more questions than answers.
What are those hidden Allen screws bolted to?
Do those metal rectangles turn and engage some lip?
Please post that too.
If at all possible (don't want to complicate your life), try to picture what happens with the back panel.
Thanks.

[Albert Kreuzer]

The Allen screws are bolted to the metal rectangles which act as locking bars.
The back panel comes off after removing the jack nuts and the small screws from the XLR. The screws "mounted from inside" are just standoffs to hold the back panel in place.
Then you need an extra-long screw driver for two mounting screws (left and right of the heatsink) and you can pull the chassis.

All in all you only have to remove 32 screws to get to the pots.
Easy, isn't it?

[J M Fahey]

Well, this *is* a Rube Goldberg/Heath Robinson design.
It does work, but needlessly complex.
1) It could have used regular nut and bolt mounting as everybody else
2) It depends on the precise alignment of those nylon cylinders "bolted from inside" as you noticed.
3) It's awkward to screw them "from inside" because you don't have much space for the device itself, you are practically forced to use a pneumatic one, the only light and compact yet powerful enough.
Still remains the alignment problem.
4) The floating front and back "fake" panels place undue stress on Jacks and XLR connectors, precisely the prone to breakage parts because of external cables.
5) The chassis is folded in many points, they obviously had to correct an error and had to add a supporting metal angle for the Reverb tank; they might just have moved the bending point a little backwards.
6) The pots have flimsy mounting (no nuts or supporting "wings"; they need that stiffening nylon tube to minimize flexing which would tear from the board.
7) They seem to use LM3886 ; at least they have 11 pins. I also see 4 TO220 devices.
I remember somebody complained about replacing IRFP530/9530 in a Loudbox; do they use some kind of Class H amplifiers?
Oh well, it's their design, they can do what they want.
It just scratches me the wrong way.
I *do* like the speaker complement chosen, very Hi Fi, specially the silk dome Tweeters.
It won't be that "Loud", but must be very accurate.

[Albert Kreuzer]

+1 to all your points.
It's an active 3-way design with the MOSFETs for bass and the LM3886 for mid/high.
Oh, and the sucker is heavy: 26kg!
BTW, I read on their HP that it is discontinued - I wonder why...