Engl E670 - Page 32

tube is operative in Hi Power mode (100 watts) only, that is, when function 44 is
activated!
Press this button to check the V4 power tube's bias (idle current). The LED chain
comprisingHiBIAS(99),InRange(100),andLoBIAS(101)indicatestheresults.
When checking a power tube's bias by pressing one of the four buttons, this red LED
lightsuptoindicatetheidlecurrentistoohigh.
The and serve to adjust the idle current accordingly.
Whencheckingapowertube'sbiasbypressingoneofthefourbuttons,thisgreenLED
lightsuptoindicatetheidlecurrentiswithinthepermissiblerange.
Whencheckingapowertube'sbiasbypressingoneofthefourbuttons,thisgreenLED
lights up to indicate the idle current is too low. The and
servetoadjusttheidlecurrentaccordingly.
Thisbutton selects the BIAS range(negativevoltage)for6L6GCorEL34tube. Refer to
theTubeMaponpage43tolearnmoreaboutselectorsettings.
This control serves to dial in a coarse adjustment of the negative grid bias for the
powertubes,therebydeterminingbias(idlecurrent).
This control serves to dial in a fine adjustment of the negative grid bias for the power
tubes,therebydeterminingbias(idlecurrent).
In order to check and adjust power tube bias (idle current), the following conditions
mustbegiven:
1. The power amp must be activated: The Standby button must be set to ON with a
speakeroranohmicload(forasignalcheckwhenservicingtheamp)connectedtoone
oftheoutputs.Otherwise,thepowerampwillnotactivate.
2.The selectedMasterknobmaybe set tothefarleft (Master: 0)topreventthesignal
frombeingroutedtothepoweramp.
3.HiPower(44)mustbeactivatedinordertocheckallfourpowertubes.
4. The amp should be switched on at least five minutes before a bias check or
adjustmenttoallowthepowertubestoheatuptooperatingtemperature.
5. When adjusting bias, the following must be taken into account: The settings of the
98BIASCHECKV4
99LEDBIASHI
100LEDBIASINRANGE
101LEDBIASLO
102BIASTUBETYPESELECT
103BIASADJUST
104BIASFINEADJ.
Additional information and important notes on checking and adjusting bias. Please
readandheed:
BIAS Adjust BIAS Fine Adj.
BIAS Adjust BIAS Fine Adj.
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