Dropped SB-230 -or, Amplifier Body Work, Part I

[Murray]

Completely appropriate questions...

We used to see such misshapen gear at Heath fairly often, and unfortunately
it was usually because it was poorly packed, not the shipper's fault.

I would either patch the pcb with non-conductive epoxy, or if you are really
handy with pcb work, etch one (beyond my patience).

What we used to do to such amplifier chasses when the metalwork was no
longer available was remove the tube and place the amp on a flat and solid
workspace with whatever thickness of wood was necessary to build up a
thickness equal to the 'normal' empty space below the chassis, and do body
work - I used a short 2 x 4 and hit it with a hammer to flatten the
distorted metal down till it met the support block inserted under the
chassis.

It worked well enough to square it up enough to fit the cabinet back on.
Torn metal was hammered back as best it could be then strengthened with a
patch or gusset plate & whatever hardware worked. Some amps (I can't
remember if it was HL-2200 or certain vintage SB-221's) had a removable
power transformer to prevent this, but ironically it was too much effort, or
not common knowledge, as was proper packing, apparently, because we got
those in trashed too.

I think the removeable-transformer amps may have had PEM nuts (captive
hardware) which sometimes broke loose. Again, whatever worked here to solve
the problem was our only option.

No point in getting worked up about keeping it original - salvaging it is
the main concern.

Oh, a hint for self-tapping screws that are overtightened and strip, if you
want to try one last thing before going up one screw size and having one
odd-ball screw (some people don't like that).

Where possible, stick a piece of wood or metal (harder option to size) under
the sheet metal that has the stripped hole, and gently tap the hole with a
ball-peen hammer until you can see the 'burr' or whatever you call the
built-up cut threads flatten back into the hole, reducing the hole diameter.
You can gently retighten the screw. It's not going to be as strong as fresh
cut full threads, but it's better than a stripped hole. If it's too far
gone, you may have to go up one screw size. If you're A.R. about it (read
u.p.t.i.g.h.t.), up all the screw sizes where you are concerned about
appearance.

I just discovered self-drilling screws - not cosmetically compatible with
Heath (not like any used on Heath), but they're great for automotive
electronics mounting...a self-tapping hardened screw with a drill point.

Murray

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