Shure SR105 service manual Service Illustrations, Gnd

in the space exposed by removal of the cover using four 6-32 x 3h1' Phillips head machine screws. Be sure to orient the screw contacts on the terminal strip in the same man- ner as the existing DIRECT OUTPUT terminal strip. Mount the slide switch next to the terminal strip in the space pro- vided, using two Phillips round head 4-40 x 3/16" machine screws. Mount the Filter Circuit board next to the Main Circuit board using the four 6-32 x 1/4" Phillips head ma- chine screws previously used to secure the cover.

TRANSFORMER

V (yellow preferred) to the upper left (viewed from terminal side) terminal of switch S4; from pin T (blue preferred) to the bottom left (viewed from terminal side) terminal of switch S4; and from pin S (red preferred) to the positive (red dot) terminal of capacitor C14.

Solder a length of 16-gauge hook-up wire (white pre- ferred) from the 28V terminal of the 28-volt terminal strip (TS1) to the bottom right (viewed from terminal side) ter- minal of switch S4 (see Figure 17, Page 18). Solder trans- former T3 leads coming out of the chassis grommet as follows:

Transformer	Part	Part Terminal
Lead Color	Connection	Designation
Red	28V Terminal	GND
	Strip (TS1)
Black	70V Terminal	70V
Yellow	Strip (TS2)	CT
Green		COM
Blue	70V Slide	Right Center
	Switch (S4)	Terminal

FIGURE 16. 70-VOLT CONVERSION:

TRANSFORMER MOUNTING

Remove the white lead from pin H on the Main Circuit board and fasten it to pin Won the Filter Circuit board. Re- move the yellowlblack lead from pin J on the Main Circuit board and fasten it to pin Y o n the Filter Circuit board. Cut a length of 20-gauge hook-up wire (yellowlblack preferred) and solder one end to pin J on the Main Circuit board.

CAUTION

Be careful not to damage board or adjacent compo- nents when soldering.

Run the soldered wire roughly parallel to the long edge of the Main Circuit board to the main wiring harness and along the harness to the 70-volt slide switch (S4). Solder the hook- up wire to the left center terminal (viewed from terminal side) of the switch (see Figure 17, Page 18). Cut a length of 20-gauge hook-up wire (white preferred) and solder one end to pin H on the Main Circuit board. Run the soldered wire twice around the two yellowlblack wires (Main Circuit board J to switch S4, and Filter Circuit board Y to poten- tiometer R41) to form a loose shield. Solder the other end of the white wire to pin X on the Filter Circuit board.

Cut three lengths of 20-gauge hook-up wire and solder them to pins on the Filter Circuit board as follows: from pin

The Amplifier conversion is now complete. Perform a dc balance adjustment as described previously in this section. Reassemble the Amplifier and return it to service.

SERVICE ILLUSTRATIONS

The pages that follow contain parts locating drawings and an overall Circuit Diagram. The parts locating drawings are of the Main and Filter Circuit boards. Foil circuit paths are shown as shaded areas on the drawings. The Circuit Diagram shows all printed circuit board and chassis- mounted parts.

GUARANTEE

This Shure product is guaranteed in normal use to be free from electrical and mechanical defects for a period of one year from date of purchase. Please retain proof of purchase date. This guarantee includes all parts and labor. This guarantee is in lieu of any and all other guar- antees or warranties, express or implied, and there shall be no recovery for any consequential or incidental damages.

SHIPPING INSTRUCTIONS

Carefully repack the unit and return it prepaid to: Shure Brothers Incorporated Attention: Service Department

1501 West Shure Drive Arlington Heights, Illinois 60004

If outside the United States, return the unit to your dealer or Authorized Shure Service Center for repair. The unit will be returned to you prepaid.