A, see the data before the rectification and product:

Second, the problem analysis: the product is a DJ mixer, excessive in EMC radiation test. From the data above is not much, but open prototype found himself inside the product to the customers a lot of measures. Before the rectification after some measures we will remove the testing over 10 DB. And the customer also requires board has two crystals can't add unscrambling, CLK list of 47 ohm resistance cannot be more than has been changed to 47 ohm (clients), magnetic bead. But teardown with agent to excessive amounts of the spectrum is the CLK radiation, it's difficult. Basic has cut off our customer requirements to change the source of the idea, but it is not completely there is no way, please continue to look down.

Countermeasures: excessive amounts of frequency on figure 4 sets of IC CLK signal radiation, crystals below the shield, CLK walk line is too long, lead to 47 ohm resistance effect is not obvious, change the 47 ohm resistor to two 22 ohm resistance, effect a bit better, then use 10 pf capacitor down, but still found that overweight 6 db, the crystals area with shielding cover, ribbon cable shielding, can see on the drawing boards at the bottom are separate, the customer request cannot be connected directly otherwise it will affect the product performance, we adopt the capacitor connection. Find out connected with capacitance, radiation allowance will be a lot of, single fulcrum largely disappeared, can pass the test.

Summary, the above cases tell us, when we are unable to change under the condition of radiation source, can be achieved by blocking the way to reduce the radiation and reasonable use, thus we need to rectify.