Corghi EM8540, Technical & Service Manual

18

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that the brake shoe and spin unit drive roller are not touching the pulley during signal 
acquisition; 

-

that the cable connecting the search circuit board (encoder) to the motherboard is 
correctly fitted and wired; 

-

the operation of the search circuit board (encoder) by means of the values displayed in 
service (see "Service programs"). Malfunction of the search circuit board prevents the 
machine from calculating the unbalance positions correctly. In this case: 

•

check that the search circuit board photo-diodes are clean; 

•

check that the fork is correctly registered relative to the search disk. 

 
If the fault persists, replace the search circuit board. 
If the fault persists even after this, replace the motherboard. 
 

During a spin cycle: 
  * the machine locks up with the beeper on; 
  * the machine resets itself. 

This fault, which is usually intermittent, can be due to a temporary power failure to the 
motherboard, or to disturbance or malfunction of the motherboard. 
Check: 
-

that the motherboard power supply cable is wired correctly and its connectors properly 
fitted; 

-

the operation of the power and control board, and especially the power voltages available 
at the Jalsk connector (refer to the attached wiring diagram for the board); 

-

that the motor power cables are decoupled from the signal cables; 

 
If the above checks do not identify any defective components, replace the motherboard. 
 

The braking sequence at the end of the spin cycle is too long or noisy 

Check: 
-

brake shoe wear. 
check for play between the shoe and lever; if there is any, tighten down the locknut on the 
fulcrum pin (the shoe should be friction fit to the lever).  

The spin unit is noisy in operation: 

Check in the following order: 
-

that the drive roller is not too worn; 

-

that the linear actuator control screw is properly lubricated; use multipurpose grade 2 
grease to lubricate it; 

-

the mechanical condition of the motor; 

-

that the connecting rod bearings are running freely. 

The mechanical parts of the balancing machine give an electric shock when 
touched 

Check the operation of the power socket ground plant (a good ground connection is essential 
for the correct functioning of the machine as well as for reasons of safety). 
-

check that the power cable is correctly connected to the transformer primary, depending 
on the mains voltage;