Q-tron Audio
Q-tron Audio
Manual PA34B4R1
Page
8(9)
5.6 Indication LEDs
These LEDs indicate fault conditions as described in the table.
Alarm
Service
Indication
Power tubes out of specification, change
power tubes
Power tubes are worn, and time for service
5.7 Mains power inlet with integrated fuse holder and mains
switch.
The power inlet accepts a standard power cord with an IEC320 plug. The 2 mains fuses
can be accessed if the power cord is removed and the fuse cover/holder is removed,
replace the fuses only with fuses of the same rating, (for 230VAC mains power fuse
rating is 4A slow blow and for 120VAC mains power fuse rating is 6.3A slow blow). The
mains switch to power up the amplifier if it is set to position 1, in position 0 the amplifier
is disconnected from mains power.
6.
Q-tron Audio Automatic Bias Calibrator
Automatically control bias and offset in our OTL amplifiers and also automatically tune to
correct bias when installing new power tubes.
1. Automatically tune bias and output offset voltage to optimal values
2. Controls the
real
quiescent, (idle)
current, see
https://qtron.se/en/articles/q-tron-
audio-bias-calibrator-technical-background
for a complete in-depth analysis and
explanation).
3. Automatic tuning of bias when replacing power tubes
The circuit automatically measures and if necessary, adjusts quiescent current and
output DC offset and works in the following manner:
If the amplifier has been on for less than 60 minutes, it will turn off instantly when the
power switch is pressed. If the amplifier has been switched on for more than 60 minutes
and the power switch is pressed to switch off the amplifier the microprocessor circuit will
start measuring the quiescent current and output DC offset, this is indicated by that the
area around the switch-on button change from being brightly lit to dimly lit.
Most times the bias values don’t need to be adjusted and then the amplifier will switch
off almost immediately indicated by the area around the switch-on button becoming dark.
