TAG MCLAREN AUDIO 100 5R Series, Service Manual

Page: 11 / 34

F3 series 100X5R service manual 7
4.0 technical outline
4.1 technical description
Introduction
The 100x5R is a five channel amplifier, featuring five identical and independent power amplifier
modules and a microprocessor control board (wth associated input and output connections).
Each of the five amplifiers features its own mains transformer, power supply components and
heatsink assembly.
The microcontroller PCB is used to:
!
power up and power down the modules in a controlled manner
!
switch the mains input to each module (via PCB mounted relays)
!
switch the loudspeaker outputs from each module (via the output relay)
!
receive and interpret the remote control commands
!
illuminate the LED displays
!
monitor the fault status of each amplifier module and take action accordingly
In addition, the microcontroller module provides TAGtronic communication bus connections to
allow the unit to communicate with other equipment, and to provide a means of uploading
firmware into the amplifier.
The micro PCB forms the ‘heart’ of the amplifier, acting as mains distribution and control
(including mains fuses for the individual modules). It is best to examine the block diagram by
considering all of the connections to and from the micro controller PCB.
Micro controller PCB
Mains distribution and switching
Mains from the IEC inlet is connected to the micro controller PCB via MLIP (live) and MNIP
(neutral). There is no mains ground connection as the unit is double insulated and fully isolated
from mains power earth.
The input mains is distributed via wire links WL4 through WL11 to the mains power relays for
the amplifier modules. There are 10 relays, RL1-RL10, 2 for each channel. This is because
each channel has ‘clean’ and ‘dirty’ mains power relays.
The concept is that the ‘dirty’ relay performs all the switching on and off for mains current into
the primary of each transformer, whilst the ‘clean’ relay only carries current during normal (on)
operation. This is to ensure that the contacts of the ‘clean’ relay do not experience inrush surge
currents or inductive spikes when mains to the modules is switched on and off, thereby
protecting the contact material, prolonging life and ensuring the best possible signal integrity
to the amplifiers themselves.
The power on sequence(for each module) is as follows:
5. Dirty relay switches ON
6. After a short delay, clean relay switches ON
7. After a further short delay, dirty relay switches OFF, allowing the clean relay
to carry the mains current
The power off sequence is essentially the reverse:
1. Dirty relay switches ON