Allen Scepter+Service+Manual电路图.pdf

ALLEN it is easy to bend a pin or mistakenly shift over one pin when putting a socket on. When re-assembling the Scepter, follow the above steps in reverse order. The diagram below shows a header and Jumper link arrangement. REMOVABLE JUMPER DUAL ROW HEADER - 31 RadioFans.CN 收音机爱 好者资料库 Audio Owner Manual Section 5 USER CONFIGURED OPTIONS There are a number of User options available on the Scepter mixer. They are implemented with removable jumper links that the user can move to different combinations of header pins; no soldering is necessary. (except for the left and right Stereo Return options). To alter any of the User Configured Options you will have to gain access to the internal circuit cards. Please read the ACCESS TO MIXER CIRCUITS procedure in the SERVICE ACCESS section. OPTION DESCRIPTIONS Input Channel Options Seven different options are available on each Input channel: Direct Out Aux send source select Pre-EQ source select Pre-EQ mute select 1 of 3 choices 1 of 3 choices for each Aux 1 of 3 choices 1 of 2 choices Direct Out Three choices are available for the Channel Direct Out. Normally the Direct Out is set to follow the Fader and Mute switch, however there may be situations when you may want the Direct Out to stay active even if the Channel is muted. This would allow you to use each input as an independent preamp. If the channel is muted, the signal would appear only at the Direct Out jack; the Aux sends and L/R pan feed would be cut. 1Post-Fader/Post-MuteThe Direct Out follows the Channel fader and Mute switch. This option is factory set. 2Post-Fader/Pre-MuteThe Direct Out follows the Channel fader but the Mute switch has no effect on the signal. 3Pre-Fader/Pre-MuteNeither the fader nor Mute switch affect the Direct out. 32 Audio Owner ManualSection 5 - - Channel Aux Send Source Select Three choices are available for each of the four Auxiliary Sends. Aux A Aux C Fader level has no effect. Same signal as PFL. 3Post-FaderAux Send follows Fader and Mute Switch. Used for Effect send. Auxes C it is there as protection from electrocution if some component should fail and cause an exposed surface to become live. The safety ground is designed to shunt this voltage to ground, causing the equipment or outlet fuse to blow. The Power supply chassis is attached to this AC ground since there are potentially hazardous voltages inside the case. The Scepter chassis and audio ground are isolated from this AC ground since the Power Supply feeds only low-voltage DC to the mixer. The Scepter chassis and audio ground are floating in respect to the AC ground; they will obtain their ground from the external equipment they are attached to. In most rack situations, there are a number of grounds tied together via the metal rack rails. This can lead to ground loops which may cause hum in a system. These ground loops can be eliminated in many casesby isolating the equipment audio ground from this metal rail. If you need to isolate the Scepter chassis then follow the procedure outlined below: The Scepter is also provided with Pin-l lifts on all its Balanced outputs. In some cases lifting Pin 1 is all that is required to fix a ground loop problem. Chassis-Audio Ground isolation procedure: 1Release the DC Power connector from the rear panel by removing the 2 fixing screws 2Carefully ease the connector out and locate the chassis lug (see diagram) 3Locate the bare wire link that is attached to this lug(see diagram) 4Cut this wire and dress it to prevent shorting. 5Re-install the connector and screws. REMOVE THESE 2 SCREWS TO FREE DC POWER JACK FROM REAR PANEL REAR PANEL DC POWER WIRES UT THIS BARE WlRf FROM THE SOLDER DC POWER INPUT 5-PIN XLR LUG TO ISOLATE THf CHASSIS FROM THE AUDIO GROUND - 37 - - Audio Owner Manual Section 6 SERVICE INFORMATION AND DIAGRAMS - h/iAIN RIBBON SIGNALS TOP VIEW 19 20 u u u u u u u u u u 1 2 VIEW ON PINS h,IAIN RIBBON SIGNALS J 17 AUDIO +15 VOLTS18 LED +15 VOLTS 19AUDIO -15 VOLTS20LED -15 VOLTS NOTE: The Silkscreen legends on the PCBs are in error (odds and evens are reversed).Pin ID locations are correct as sho&m above. SCEPTER RACK MIXER - 10 RACK SPACES DEPTH BEHIND PANEL 1 1 9 ( 4 8 3 ) PANEL (94) 1 .4 HEIGHT ABOVE (36) PANEL (HANDLES) ! CHASSIS1 .o RACK EAR / (25)WIDTH II f- 1 7 ( 4 3 2 ) -_-_- MPS-8R POWER SUPPLY - 2 RACK SPACES 1 1 9 ( 4 8 3 ) ALL DIMENSIONS IN INCHES & (MM) - 1 - (280)