harbach-electronics sk-301 Benutzerhandbuch

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(1) SK-301 “S oft K ey” Circuit Board  Assembly
(1) Nylon Threaded Spacer
(2) 6-32 x ¼” Screws
(1) #8 Bent Solder Lug
(1) #6 Internal Tooth Lock Was her

To start the  installation, read these instructions very carefully.  Unplug the amplifier and

remove any input, output and c ontrol ca bles that may be co nnec ted to the back of the amplifier.
Remove the chassis from the case, turn the rear of the amp tow ard you, and remov e the rear panel
and left corner piece from the chassis.  You are now ready to proceed with the installation.

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The exact m oun ting  loca tion of the SK-301 is not too critical.  Be sure to keep the leads as
short as pos sible.  The m ost convenient place I have found is just to  the left of the filament
choke.

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Turn  the chassis over and mark a location approximately 1-1/8” in from  the re ar of the
chassis and 2-9/16” to the right of the center of the middle U-shaped cutout in the bottom
plate of the chassis.  This is where the mounting spacer attaches to the SK-301 and also
the location of the hole for the mounting screw.   The hole should be located nearly under
the inside tube s ockets.  V ery carefully drill a hole that w ill clear a 6-32 screw at the point
you just marked (#2 7 drill).  D o not use too m uch pre ssure b ecaus e you w ant the drill to
stop after just penetrating the chassis.  Clean up any burrs from the hole.

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Turn  the amplifier back over.  Rem ove the screw directly under the column of feed-throughs
located next to the filament choke.  Place  the 2-ho le so lder lug ov er this screw a nd re -install
the screw.

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Attach the threaded nylon spacer to the SK-301 through the large m ounting hole in the
corner of the circuit board using one of the 6-32 x ¼” screws and tighten well without
stripping the threads  in the s pacer. Plac e the #6 lock washer onto the remaining 6-32 x ¼”
screw and put it through the hole you just drilled.  Attach the nylon s pac er (and c ircuit
board) to the chassis.

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In the following steps, route the wires under the SK-301 circuit board and/or under the
filament choke as required.

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Connect the BLACK wire fro m the SK-301 circuit board to the solder lug you just installed
and s older.

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Route  the GREEN wire  from the SK-301 circuit along the chas sis and u p into the
transformer com partm ent and c onnec t GREEN wire to the right side of the bottom feed-
through (ne arest the transformer) and solder.

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Route the RED wire from the SK-301 under the circuit board and connect to the top feed-
through and solder.