SAFETY AND ISOLATIONSAFETY AND ISOLATIONsymbol should be replaced with parts of the type originally
Under no circumstances should any form of repair orfitted. This applies particularly to those resistors which are
?stood off? the printed circuit boards.
maintenance be attempted by any person other than a
competent technician or engineer. Most of the circuitry onChassis Operation and Alignment
the chassis is isolated from the AC supply by T801, C831,The majority of chassis functions are implemented within
R821, IC802 and 6mm air gaps. To maintain this safetyIC504 and its associated circuitry. These are controlled by
factor ensure that, after repair, any gaps or leakage pathsthe micro-controller IC701 via the I2C bus, a two wire bus
are not reduced by protruding wires etc., following(SDA, Serial Data and SCL, Serial Clock). The micro-
component replacementcontroller contains twenty adjustable parameters between
00-13 (hex) which are used to control the functions of IC504
NOTE: although the output supply paths from the power. (See Adjustments for further details on how to adjust or reset
supply section are isolated from the incoming AC supply, thethese.)
bridge rectifier and the control and regulation circuits are notHandling Precautions - Static Electrical Charge
isolated. Therefore, when servicing the power supply sectionThe receiver contains devices which may be damaged by
of the chassis, the AC supply should be connected via anstatic electrical charges during handling. To avoid damage,
isolating transformer of at least 200 watts rating.soldering irons should be earthed, and service personnel
should, ideally, wear wrist straps earthed through a 1M ohm
The power supply section remains charged with respect toresistor. If the latter is not practical, they should discharge
chassis for 30-60 seconds after switching off. Care shouldthemselves by touching an earthed point. Sensitive static
be taken to avoid touching the power supply area of thedevices should be packed in suitable conductive containers.
chassis during this time.IMPORTANT: although the receiver chassis is isolated, the
Components marked ! in the parts list are safety approvedAC supply should be disconnected during service
types and should be replaced only with components suppliedreplacement of such static devices.
or approved by our Service Department. It is also
recommended that components not marked with the safety
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ACEC
