Mackie SRM2850 - Appendix A: Service Information; Troubleshooting

Owner’s Manual
13
Owner’s Manual
Appendix A: Service Information
Poor bass performance
• Checkthepolarityoftheconnectionsbetweenthe
  mixerandthesubwoofers.Youmayhaveyour
  positiveandnegativeconnectionsreversedatone
  endofonecable,causingonesubwoofertobe
  out-of-phasewiththeother.
• Poorbassperformancemaybetheresultofbad
  ACpower.Seethesectiontitled‘ACPower’on
  thepreviouspageforfurtherdetails.
Poor sound
• Isitloudanddistorted?Makesurethatyou’renot
  overdrivingastageinthesignalchain.Verifythat
  alllevelcontrolsaresetproperly.
• Istheinputconnectorpluggedcompletelyinto
  thejack?Besureallconnectionsaresecure.
Noise
• Makesureallconnectionstotheactive 
  subwoofersaregoodandsound.
• Makesurenoneofthesignalcablesarerouted
  nearACcables,powertransformers,orother
  EMI-inducingdevices.
• IstherealightdimmerorotherSCR-based
  deviceonthesameACcircuitasthesubwoofer?
  UseanAClinelterorplugthesubwooferinto
  adifferentACcircuit.
Hum
• Trydisconnectingthecableconnectedtothe
  inputjack.Ifthenoisedisappears,itcould 
  bea“groundloop,”ratherthanaproblemwith
  thesubwoofer.Trysomeofthefollowing 
  troubleshootingideas:
• Usebalancedconnectionsthroughoutyoursystem
  forthebestnoiserejection.
• Wheneverpossible,plugalltheaudioequipment’s
  linecordsintooutletswhichshareacommon
  ground.Thedistancebetweentheoutletsandthe
  commongroundshouldbeasshortaspossible.
Ifyouthinkyoursubwooferhasaproblem,please
checkoutthefollowingtroubleshootingtipsanddo
yourbesttoconrmtheproblem.VisittheSupport
sectionofourwebsite(www.720trees.com)whereyou
willndlotsofusefulinformationsuchasFAQsand
otherdocumentation.Youmayndtheanswertothe
problemwithouthavingtopartwithyoursubwoofer.
Troubleshooting
No power
• Ourfavoritequestion:Isitpluggedin?Makesure
  theACoutletislive[checkwithatesterorlamp].
• Ournextfavoritequestion:Isthepowerswitch
  on?Ifnot,tryturningiton.
• Makesurethelinecordissecurelyseatedinthe
  linecordsocketandpluggedallthewayintothe
  ACoutlet.
• IstheRunningManlogoonthefrontpanel 
  illuminated?Ifnot,makesuretheACoutlet
  islive.Ifso,referto“Nosound”below.
• TheinternalAClinefusemaybeblown.Thisis
  notauserserviceablepart.Ifyoususpectthe
  AClinefuseisblown,pleaseseethe"Repair"
  sectionnext.
No sound
• Istheinputgainknobfortheinputsource 
  turnedallthewaydown?Verifythatallthevolume
  controlsinthesystemareproperlyadjusted.
  Lookatthelevelmetertoensurethatthemixer
  isreceivingasignal.
• Isthesignalsourceworking?Makesurethe 
  connectingcablesareingoodrepairandsecurely
  connectedatbothends.Makesuretheoutput
  levelcontrolonthemixingconsoleisturnedup
  sufcientlytodrivetheinputsofthespeaker.
• Makesurethemixerdoesnothaveamuteonora
  processorloopengaged.Ifyoundsomethinglike
  this,makesurethelevelisturneddownbefore
  disengagingtheoffendingswitch.
• Hasitshutdown?Makesurethereisatleast
  sixinchesoffreespacebehindeachsubwoofer.