Swr_sm_900_phantom_power_rework 电路图 维修原理图.pdf

SM-900 Phantom Power rework.doc 1 SWR SM900 Phantom Power rework instructions Caution: Disconnect AC power cord and all other cables before servicing. 1. Remove top cover and set aside. 2. (Optional step) Remove the four screws from the underside of the chassis that secure the rear heat sink/power module. Leaving the wires connected, move module aside. 3. (Optional step) Remove knob marked “XLR PAD” by pulling it firmly toward the rear. Unscrew the 7/16” nut and washer from the XLR PAD pot shaft and set pot aside, leaving wires connected. 4. Unsolder the 47uF capacitor from between the red wire and the solder pad marked “2” on the bottom preamp PCB. Save the capacitor. Re-solder the red wire to the pad marked “2”. 5. Unsolder the 47uF capacitor from between the black wire and the solder pad marked “3” on the bottom preamp PCB. Save the capacitor. Re-solder the black wire to pad marked “3”. 6. Unsolder the 1.5K resistor from pin 2 of the XLR. Solder the positive lead of one of the 47uF capacitors to the pin 2 of the XLR. Solder the negative lead of the capacitor to the 1.5K resistor. 收音机爱好者资料库 Ra d i o Fa n s .CN SM-900 Phantom Power rework.doc 2 7. Unsolder the black from pin 3 of the XLR. Solder the positive lead of the other 47uF capacitor to the pin 3 of the XLR. Solder the negative lead of the capacitor to the black wire. 8. Reinstall the XLR PAD pot; carefully dressing the capacitor and resistor leads. 9. Reverse steps 2 and 1. 收音机爱好者资料库 Ra d i o Fa n s .CN