EBME Forums Forums Maintenance Technical Assistance Ultrasound logic 200 Interference problems

Dear Colleagues,
System: LOGIC 200 PRO
Manu : GE
Probe : Endocavitary 6.5 Mhz
: Convex 3.5 Mhz
Mains : 220 Volts
F : 50 Hz
Application : OBS/GYN

I have an Intriguing problem on ultrasound, there is a noise pattern that i cnt recognise, it s not a noise generated from mains or from RF power cables( they have a different pattern such horizontal line accross the image).
if some one able to recognise the noise pattern please help. i need to know the source of this noise to know how to solve the problem .
PS : It s not a probe problem since the machine operate normally if the location is changed, and i cnt really change the location since , the machine is used in operation room.

Thank you in Advance

Best Regrds
BNad

Hi,
Do you generally perform the periodic maintenance of the equipement?
The problem can be due to some deffectives contacts on the electronics boards.
Inspect the output voltages at the power supply stage.

Best regards.

This looks very much like external RF interference to me, as you have moved the machine to another location and it wasn't evident. Try changing the frequency of the probe the problem may get worse or better. Also try holding the probe in the air making an aerial with your finger and thumb around the end of the transducer, the noise should get worse. Is the problem intermittent i.e. when RF Diathermy is being used in another theatre room.

Aye, it is RF interference . i have discovered that the whole body is acting like an antenna , as an update you dont need even to touch the probe for the interference to appear, just wave ( with ur hand) near it by 2 inches ( 5 cm ) or so , the interference will appear .
location change does solve the problem . however due that the system is an OBS/GYN for IVF operations room i cnt really change the location . ( it s quite costy to move the operation theatre ) i am thinking in the following solution , Since our mains are 50 Hz
and the machine takes both 50/60Hz , if i give it 60 hz it may solve the problem.

I don't think the problem is with the mains frequency at all, by your latest description of the fault. Is this problem happening all the time or is it intermittent. If Intermittent it will be much easier to find the culprit, probably a Diathermy near by. If the problem is there perminantly then you have a bigger problem. Most likely caused by a RF transmitter somewhere near to the Hospital in my experience. There are mats that can used for shielding external RF interference, can't tell you how good they are though.

it s is by no means intermittent , the idea of the frequency changing occurred when i purchased an on-line ups ( it can last at least 1 hour ) the noise intensity was reduced around 50% if you unplug it from the main and operate it on the ups alone. the thing i used an U/S from another manufacturer ( for troubleshooting purposes) and it doesn't have the same problem , this adds to the confusion overall.