RIGOL                                                                                                                                                   
                                                                     
Service Guide for DM3000 Series 
 
2.  Ground circuit contains keyboard, LCD, USB Host, BNC board, LAN/GPIB board and the 
host CPU of motherboard. 
 
3.  The AC power inpour into the multimeter via power socket and connect with transformer 
through filter board  that divides  it into multi  low voltage and floating into  circuit and 
ground circuit respectively. The power supply of ground circuit is 9V AC voltage and the 
floating circuit is a group of 8.5V AC voltage and two groups of 17V AC voltage. The 
commutate, filter and regulation circuit in floating and grounding circuit transform the 
low-voltage AC into stable DC voltage and supply power to each circuit.   
 
   Connect the control circuit of multiplexer board with host CPU and then connect the 
output terminal of multiplexer board with analog front-end. 
 
  when measuring,the host CPU will send commands to control the analog front-end to 
switch  function  and  range.  Then the  analog  front-end  return the  result  from  A/D 
transform and cymometer to host CPU, eventually, the host CPU will calibrate these 
results and display according to control the LCD.   
 
  When multiplexer measuring, firstly the host CPU will control the analog front-end to 
switch  to  multiplex  board,  and  then  send  commands  to  shift  to  certain  channel, 
eventually, perform same procedures to get final result.