[sdiy] FCC And Other Testing

Richie Burnett rburnett at richieburnett.co.uk
Wed Jan 13 17:32:29 CET 2021


As an Engineer who has been responsible for EMC compliance of several 
company's products in prior roles, and an observer of Eurorack equipment, I 
think I would say that it would be almost impossible to *ensure* compliance 
of an installation through the lifetime of the product.  The Eurorack 
systems that I've seen often have substantial sized open holes in the 
enclosure where there are no modules installed, no copper fingers to ensure 
contact between module front panels and the adjacent module or enclosure 
wall, and a plethora of different length cables breaching the front face of 
the "enclosure" (with little or no use of ferrite sleeves etc.)  Given that 
a user not trained in RFI and EMC compliance can then swap modules, change 
the power supply, etc,  how could anyone possibly guarantee EMC or FCC 
compliance?

That's not to say that I think Eurorack synths are a disaster waiting to 
happen.  In EMC risk terms they are probably quite low because they 
generally don't contain lots of high-speed digital stuff, or high-powered 
switched mode power converters.  The only issue I have been made aware of 
was one that Tony Allgood had with 100Hz hum and oscillators going out of 
tune when a neighbour used an amateur radio transmitter.  Whilst very 
annoying it was presumably not life threatening, unless Tony went round to 
the neighbours house with a big stick...  ;-)

The approvals responsibility for Eurorack synths must surely be similar to 
that of a PC manufacturer (system builder)?  If you sell a *finished* 
product into a market it needs to be compliant.  If you sell a component for 
a system then it is the system manufacturer's responsibility to ensure 
compliance when installed in the final product.  But if your component is 
particularly troublesome RFI wise, then you might not find many system 
builders coming back to buy more.  For instance, I've seen electronic 
equipment for development use in labs that was not compliant and labelled 
"EMC/FCC compliancy is the responsibility of the end-user" and whilst we 
didn't worry about this for research use in the lab, it meant that the use 
of the same equipment in an installation sold to an end-user was not 
feasible.  In fact the equipment in question generated so much RF emission 
at some frequencies achieving compliance was impossible.  My thoughts are 
that if it could have easily been made compliant then the manufacturer would 
have done so!

-Richie, 


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