M-Audio Hammer 88 Pro - Page 33

damaged,otherwiseneedtobereplacedandrepaired.
b) UnderthecircumstancethatDJ1has9V,U2'sPIN3canoutput5V.Ifitstillcannotberepairedafter
welding,U2hasbeendamagedandneededtobereplaced.

c) Useamultimetertomeasurewhetherthevoltageof3.3Vand
5Visshortwiththeground.Ifshort,
cutthelineandcheckthelocationofshortcircuit.
d) DeterminewhetherU1canoutput3.3V,checkwhetherPIN5has3.3V,ifnot,thenreplacethechip.
e) Checkwhetherthereis3.3VatbothendsofL4todeterminewhetherthere
isvirtualweldingor
damage.
f) DeterminewhetherU31canoutput3.3V,checkwhetherPIN2has3.3V,ifnot,thenreplacethe
chip.
g) Checkwhetherthereis3.3VatbothendsofL12todeterminewhetherthereisvirtualweldingor
damage.


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