BBK SP-014 Service Manual
SP-014
servicemanual
SP-014PrincipleandServicing
1.SP-014workingprinciple
ExternalinputsignalsareinputtedtoinputboardbySC1,anditsleftchannelsignaloutputstopin3
ofsocketXSthroughR127,topoweramplifierboardthroughflatcableXP2;afterreachingpower
amplifierboard,itisdividedinto2paths,onepathreachespotentiometerRP100Aforbassadjustment
throughR100(RP100isduplicatepotentiometer,whichcanadjustleftandrightchannelsatthesame
time);theotherpathsreachespotentiometerRP101AfortrebleadjustmentthroughcapacitorC100
(RP101isduplicatepotentiometer,whichcanadjustleftandrightchannelsatthesametimes);andthe
twopathscombineonepathaftertreble/bassadjustmentthroughresistorR108,R107tosendto
potentiometerRP102Aforvolumeadjustment(RP102isduplicatepotentiometer,whichcanadjustleft
andrightchannels);volumeadjustmentsignals,throughR101dampingandC101coupling,aresentto
pin11ofN100TDA7265forpoweramplifying(TDA7265isadual-channelpowerIC),thenoutput
signalsthroughpin2afteramplificationtoloudspeakerdirectly.Signalfloedirectionofrightchannelis
similarwiththatofleftchannel.
Thisplayeriswithpower-onmutefunction,anditsprincipleis:whenpoweron,+VScharges
capacitorC110throughR110,triodeV100cutsoff,MUTEpinofTDA7265inputshighlevel,muteof
TDA7265iseffective,thewholesethasnooutput;whencapacitorC110isincharging,positivevoltage
increasesto6V,V100ison,MUTEturnsintolowlevel,muteisoff,outputisnormalandtheconcussion
soundisremovedwhenpoweron.
2.Troubleshootingflow
(1)LeftchannelhasnooutputTroubleshootingflowfor“”osshownasthefollowingfigure2.1:
-1-
Leftchannelhasnooutput
Check
whetherpin1(or
3)ofpoweramplifier
boardXS2haswaveform
afterinputting
signals
N
ChangeR127andR129
N
Changeinputterminal
Y
whetherpositive
waveformofcapacitor
C101(orC111)is
Check
Y Y
normal
Whether
waveformofpin2,4of
N100isnormal
N N
ChangeRP102
ChangeN100
Figure2.1troubleshootingflowchartfor"Leftchannelhasnooutput"
Changeloudspeaker
-2-
(2)Troubleshootingprocessfor“Powernoon”isshownasthefollowingfigure2.2:
Powernoton
Check
whetherprotector
tubeonpowercordhas
beenburnt
down
Y
Check
whetherprotector
tubeofpoweramplifier
boardhasbeenburnt
down
Y
Measure
whetherpoweramplifier
boardpowercordandground
wireimpedance
iszero
Y
ChangeN100,transformer
andprotectortubetosolve
Check
N
N
whetherpower
amplifierboardprotector
tubehasbeenburnt
down
Change
C120,C121,
C122,C123andcheck
whetherthetrouble
isremoved
Changetransformerand
protectortubeanditisOK
Check
N
Y
N
whetherpower
amplifierboardpower
voltage+/-22Vis
normal
ChangeN100tosolvetheproblem
ChangeN100tosolvethe
N
problem
Figure2.2Troubleshootingflowchartfor"Powernoton"
-3-
Loading...