Trace Elliot TA200S Chassis Extraction from Cabinet

[nevetslab]

Our Guitar Dept (CenterStaging, LLC Burbank, CA) sent this Trace Elliot TA200S Combo Amp over to me, with the complaint that the Reverb isn't working. I've never seen this, so moved it to the inspection bench in my shop to have a look. Removed the upper and lower cover grilles of the front, which revealed two sets of four 5" speakers above/below a control panel. I saw numerous pot knobs missing, and one control shaft broken off. Rear panel connector panel is missing numerous threaded Cliff Chrome Ground bushings and the shaped bushing that goes with it.

I removed all of the visible panel and chassis fasteners, expecting I could then slide this assembly out of the cabinet. Great assumption. WRONG! Chassis assembly is NOT free to move anywhere.





I Googled this unit, did come up with a thread on this forum on a TA50, I think it was, and learned from the problem that member had, he had to break the glue bond between the bottom side of the chassis to the floor of the chassis. Then it came out. It was a much simpler model mechanically than this beast. Using a thin 24" scale, I was able to probe under the chassis and the cabinet floor, finding numerous areas that I assumed were all glue joints. I had removed both recessed cabinet handles which gave me a look inside, revealing a baffle separating the left and right halves of the two speaker sections internally, and a view of the PCB assemblies of both front and rear sections of the folded chassis. Toroidal Power Xfmr in the power supply.

With all the chassis fasteners removed, I fetched a 12" hack saw blade and loaded it into a blade holder and tightened that up with channel locks to get as much grip on that thin blade. I pounded my Wiha bladed screwdriver between the bottom front flange of the chassis and cabinet, so I could slip the hack saw blade in to saw thru what I expected to be glue joints holding the chassis from moving. I think I did get thru all of the obvious joints, but that left me with what feels like some chassis mounted screw heads that must be protruding below the chassis floor. I see one area of a small PCB that I assumed to be Pem Studs holding the board to the floor. I no longer believe that.



Thus far, whatever my hack saw is cutting at, I can't get thru it, It wouldn't surprise me if I HAVE engaged one or more screw heads that appear to be sitting back between the inside span of the speakers in the middle of the lower panel. I can't see what I'm dealing with, and it out of reach from going thru the handle openings. No fasteners thru the bottom of the cabinet to account for this obstruction, and have spent over two hours trying to cut thru whatever is refusing to yield.

Any ideas?

[The Dude]

I don't have all the solutions, but there is an amp assembly in the speaker cabinet. I believe if you remove the lower left speaker you will see it. I'm thinking there may be a wire harness going to the preamp (center part) that is keeping you from removing it. This is just speculation, but maybe will help you.

[g1]

Agree with The Dude. Whenever I come up against something like this, I start pulling speakers to get a look around inside.

[nevetslab]

Very good suggestion. I removed the two middle speakers, both of which had virtually NO Service Length of the wires from the two PCB's feeding the speakers. I did manage to fold them over, straining the wires, but enough to keep them out of the way.

What I found is two wooden cleats at the base of the center divider of the cabinet separating the two sets of speakers. I managed to cut thru the cleats, which was a bad move. Using my thin 24" scale with the speakers out of the two baffle holes, I don't feel anything on the chassis floor of the assembly being fastened to the floor of the cabinet. But still don't yet have any movement forward of the folded chassis that is fitted into this cabinet. There is a series of cleats on each side of the chassis front panel that follows the two folds of it (three separate plains). There's no gap between the edge of the panels. which makes me wonder if there was any glue used underneath the ends of the panels.



I just found the problem (besides what problem I introduced by cutting thru the cleats and center cabinet divider from the floor of the cabinet!) In this last photo, having removed the two lower end speakers from each side of the baffle, there is a wood screw protruding thru the cleat to which the chassis speaker baffle is mounted to on the left and right sides of the cabinet.

UNDERNEATH THE CUSHIONED SHAPED CLEATS TO WHICH THE SPEAKER GRILLES ARE MOUNTED, THERE ARE WOOD SCREWS THRU THE CHASSIS INTO AND THRU THE CABINET CLEATS ON THE INSIDES OF THE CABINET. INVISIBLE TO THE SERVICE TECH AND IS THE REASON (BESIDES GLUE JOINTS ON THE BACK SIDE OF THE CHASSIS TO THE CABINET FLOOR) WHY YOU CAN'T REMOVE THE CHASSIS ASSEMBLY FROM THE CABINET.

I NOW HAVE TO PRY OFF THE SHAPED CLEATS THAT ARE GLUED TO THE CHASSIS BAFFLE TO FIND AND THEN REMOVE THE WOOD SCREWS INTO THE CABINET CLEATS ON BOTH SIDES OF THE CABINET. I THINK THEN I CAN FINALLY REMOVE THE CHASSIS ASSEMBLY.

TRYING THAT NOW.

[nevetslab]

I got the chassis out of the cabinet, after prying off the speaker grille cleats glued onto the front panel of the chassis. I was expecting to find screws thru and into the upper baffle area, but it was just the two screws thru the lower baffle cleats of the speaker grill that was preventing the removal of the chassis from the cabinet. I thought I had felt cutting thru glue joints on the bottom of the chassis to the floor, but after extracting the chassis, there was no evidence of that. But definitely sliced thru the bonding of the center partition separating the left and right halves of the cabinet.

I looked to see if I could slip in some 1/16" thick fiberglass board material, but it wouldn't fit. AND, the rigidity of the center board still feels nice and solid, so I may just find something to slip into that thin gap I cut with the hack saw blade, and drive a few screws into the board from the bottom.

I had to remove a push/pull 50k linear pot along with an adjacent 50k linear pot that had a broken fiber wafer, but, for some reason, the carbon track of that pot didn't fracture. I was able to glue it back together. After removing the Nobel 50k Linear Push/Pull Pot/Switch, which has its' spline shaft broken off, I was doubtful I'd be able to find a replacement. I lucked out and found on ebay for $2.70 ea, and ordered a couple of those. Won't see them until the middle of March.

I found the Footswitch jack for the Alesis Digital Reverb/Chorus PCB assy was buggered, where the thread of the pot wouldn't accept the Cliff Chrome Ground Sleeve without it cross-threading. I replaced that pot, then ordered more of the Chrome Ground sleeve/tapered washers to restore the rest of the pots on that I/O panel/PCB.

Photos of the insides of this Trace Elliot TA200R Amp:

[Jazz P Bass]

You, my friend, have the patience of a Saint and the tenacity of a Bulldog.

[Greg Robinson]

Not to compare you to this Steven, but your struggle reminded me of a client who brought me a combo amp a few years ago they'd struggled replacing the speaker in. They hadn't realised it was necessary to first remove the amp chassis in order to remove the speaker, and had cut a couple of triangles out of the bottom base board (glued in, think it was a Marshall). Of course they'd also completely chewed up the fastener heads, and not managed to tighten them again with the new speaker. Were wondering why they had rattle...
Actually managed to track down a photo!