Idling Current And Dc Offset Voltage Alignment - Marantz PM7200N1B Service Manual

8. IDLING CURRENT AND DC OFFSET VOLTAGE ALIGNMENT

8.1 Quiescent Current Adjustment for Class AB
-Set to CD mode with no input, minimum volume position &
mains supply at 230 V ±5 %.
-Power up the unit, adjust SLOWLY 3299 (L) & 3300 (R) until
voltage across L-Channel -----3335 (T007 / T006) & 3337 (T009
/ T010), R-Channel ----- 3336 (T013 / T014) & 3338 (T015 /
T016) is as per the table below.
Time
after 30 sec to 1 min*
- After 30 min, the voltage should settle down to 18 mV ± 3 mV.
* Start from cold condition.
8.2 Quiescent Current Adjustment for Class A.
- Next, switch to Class A operation. Adjust SLOWLY 3309 (L)
& 3310 (R) until voltage across L-Channel ----- 3335 (T007 /
T006) & 3337 (T009 / T010) , R-Channel ----- 3336 (T013 /
T014) & 3338 (T015 / T016) is as per the table below.
Time
after 0 sec to 30 sec**
- After 30 min, the voltage should settle down to 90 mV ± 5 mV.
** Continue immediately after 8.1
REMARKS:
- Please take note that for both Class AB & A alignment, at all
time during adjustment, refer to the higher reading of each
channel.
Quiescent Current
Measurement point
8.3 DC Offset.
- Adjust 3263 and 3264 until DC offset voltage is less than ±10 mV
at Speaker output terminal.
Voltege
0.3 mV to < 0.4 mV
Voltage
65 mV to <70 mV
POS.No.
3335
3337
3336
3338
34