Application Story 2
The Equipment:
A temperature controller, with an analogue PCB, a digital PCB and a LED display.

The Objectives:
The product was required to meet the heavy industrial limits for radiated immunity, but failed at a range of frequencies around 35 MHz with the temperature reading error well outside of the customers specified accuracy. At a relatively low frequency it was likely that one or more cables were responsible for this noise coupling. Cables were disconnected or suppressed one at a time until the coupling route was identified.

The Investigation:
The system could now be removed from the chamber and the PCB together with the coupling cable placed on the ETSi 4334. An external noise source was used in inject a 35 MHz signal into the cable. An X-Y plot of the PCB at the same frequency showed the areas which were affected; In this case the input stages of a differential amplifier. From this information the design engineers were able to apply suitable filtering to just those areas of the PCB that needed it.
The temperature controller was then re-assembled and found to be compliant when returned to the chamber.

Conclusion:
The use of the ETSi Scanner led to a solution which filtered the noise from the affected circuitry, and avoided expensive screened cable or impracticable external ferrites.

Home Page ETSi4334 Applications Samples Accessories Downloads F.A.Q.s Step by Step Contact Us

ETSinstruments Tel: +44 (0)1371 856061 Fax: +44(0)1371 856144
E-mail:
sales@etsi.co.uk Web: www.etsi.co.uk