Sec. 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 Sec. 15.31.
    (i) Under these test conditions, the system under test shall not 
exceed the radiated emission limits specified in Sec. 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 Sec. 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 Sec. 15.31. Under these test 
conditions, the system under test shall not exceed the radiated emission 
limits specified in Sec. 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 Sec. 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 Sec. 15.31. Under this 
procedure, CPU boards that comply with the limits in Sec. 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 Sec. 15.107 shall be performed in 
accordance with the procedures specified in Sec. 15.31 using a 
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 Sec. 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]