Abstract: Based on experience acquired in practical work,the authors summarize in this paper the main structure of the ADU?07e and the problem as to how to check the status of the ADU?07e from self test and especially sum up precautions for common trouble phenome?na during field work and troubleshooting method for the operation of the GMS?07 comprehensive electromagnetic observation system. Practical examples illustrate abnormal data due to lack of ground electrode or chopper closure during recording data which cannot be checked from self test. The trouble detection method is also applicable to the GMS?07 system used in conventional MT exploration.