Ground Lift Switch Circuit ⊥ to Chassis Switch

11. Ground Lift Switch CIRCUIT ⊥ TO CHASSIS SWITCH

Using the ground lift switch CIRCUIT ⊥ TO CHASSIS SWITCH (22) lets you separate the audio signal ground from the enclosure ground (safety earthing). This helps to solve problems with hum or noise without jeopardizing safety standards. If several units with ground lift switch are installed in a common enclosure or rack system, it is recommended to set the ground lift switches of all devices but one to “ungrounded”. Set to “ungrounded”, the impedance between signal ground and enclosure is: 100 k ohms // 100 nF. It is necessary to maintain the immunity from EMV.

12. Fuses

Location	Pos.	Used for	Value	Dimensions	Standard

Fuse switch (11)	F601	Mains fuse 230 V~ AC	T4AL 250V	5 x 20 mm	IEC 127
Fuse switch (11)	F601	Mains fuse 115 V~ AC	T8AH 250V	5 x 20 mm	IEC 127
Board 86243	F602	Mains fuse AC	T1AL 250V	8.5 x 8.45 mm	IEC 127
Board 85272	F502	Battery fuse 24 V DC	25AL 32V	Flat type fuse	DIN 72581-3
Board 85272	F503	Battery fuse 24 V DC	25AL 32V	Flat type fuse	DIN 72581-3
Board 85272	F504	Power-AMP 1	T6.3AL 250V	5 x 20 mm	IEC 127
Board 85272	F505	Power-AMP 2	T6.3AL 250V	5 x 20 mm	IEC 127
Board 85272	F506	Power-AMP 3	T6.3AL 250V	5 x 20 mm	IEC 127
Board 85272	F507	Power-AMP 4	T6.3AL 250V	5 x 20 mm	IEC 127

Changing The Fuses F502 And F503 (see diagram 11):


Caution		Unplug the mains cord and disconnect batteries before opening the appliance!

The battery fuses F 502 and F503 are located on the mains (power supply) printed board assembly 85272 behind the AMP-battery connectors. In case they need to be replaced, commence as follows:

-open the appliance by removing the 9 screws that lock the cover-plate

-remove the mains input printed board assembly 86243 that is located at the rear inner wall. Therefore, unplug the yellow/green ground conductor form the corresponding connector at the rear inner wall. To remove the AMP-plug, press its lock-piece

-now, you have to remove the 3 screws of the mains-input printed board assembly 86243 marked “C” (refer to the picture of the rear panel on page 21).

-disconnect the 6-pole flat cable between the two relays on the mains-input printed board assembly 86243 that is connected to the male multi-point connector B602

-now, the hinged mains-input printed board assembly 86243 can be turned up. In doing so, be careful not to damage any wiring or other parts

-the fuses F502 and F503 are now easy to get to and can be removed to the top

-for re-installing the mains-input printed board assembly 86243, proceed in opposite order:

tighten the mains-input printed board assembly 86243 with the 3 screws marked “C”, where each, the mains plug (10) and the mains selector switch (12) need to be connected using individual screws and self-securing nuts M3.

-reconnect the 6-pole flat cable to the multi-point connector B602

-reconnect the yellow/green ground cord to the ground connector on the rear panel; make sure that it sits tight

-closing the appliance: reattach the cover-plate with 9 screws M3 x 6 DIN 7500