§ 15.32   Test procedures for CPU boards and computer power supplies.

   Power supplies and CPU boards used with personal computers and for
   which separate authorizations are required to be obtained shall be
   tested as follows:

   (a) CPU boards shall be tested as follows:

   (1) Testing for radiated emissions shall be performed with the CPU
   board installed in a typical enclosure but with the enclosure's cover
   removed so that the internal circuitry is exposed at the top and on at
   least two sides. Additional components, including a power supply,
   peripheral devices, and subassemblies, shall be added, as needed, to
   result in a complete personal computer system. If the oscillator and
   the microprocessor circuits are contained on separate circuit boards,
   both boards, typical of the combination that would normally be
   employed, must be used in the test. Testing shall be in accordance with
   the procedures specified in § 15.31.

   (i) Under these test conditions, the system under test shall not exceed
   the radiated emission limits specified in § 15.109 by more than 6 dB.
   Emissions greater than 6 dB that can be identified and documented to
   originate from a component(s) other than the CPU board being tested,
   may be dismissed.

   (ii) Unless the test in paragraph (a)(1)(i) of this section
   demonstrates compliance with the limits in § 15.109, a second test shall
   be performed using the same configuration described above but with the
   cover installed on the enclosure. Testing shall be in accordance with
   the procedures specified in § 15.31. Under these test conditions, the
   system under test shall not exceed the radiated emission limits
   specified in § 15.109.

   (2) In lieu of the procedure in (a)(1) of this section, CPU boards may
   be tested to demonstrate compliance with the limits in § 15.109 using a
   specified enclosure with the cover installed. Testing for radiated
   emissions shall be performed with the CPU board installed in a typical
   system configuration. Additional components, including a power supply,
   peripheral devices, and subassemblies, shall be added, as needed, to
   result in a complete personal computer system. If the oscillator and
   the microprocessor circuits are contained on separate circuit boards,
   both boards, typical of the combination that would normally be
   employed, must be used in the test. Testing shall be in accordance with
   the procedures specified in § 15.31. Under this procedure, CPU boards
   that comply with the limits in § 15.109 must be marketed together with
   the specific enclosure used for the test.

   (3) The test demonstrating compliance with the AC power line conducted
   limits specified in § 15.107 shall be performed in accordance with the
   procedures specified in § 15.31 using an enclosure, peripherals, power
   supply and subassemblies that are typical of the type with which the
   CPU board under test would normally be employed.

   (b) The power supply shall be tested installed in an enclosure that is
   typical of the type within which it would normally be installed.
   Additional components, including peripheral devices, a CPU board, and
   subassemblies, shall be added, as needed, to result in a complete
   personal computer system. Testing shall be in accordance with the
   procedures specified in § 15.31 and must demonstrate compliance with all
   of the standards contained in this part.

   [ 61 FR 31048 , June 19, 1996, as amended at  62 FR 41881 , Aug. 4, 1997]

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