Fostex G24S Service Manual page 32

4.3.15 Dynamic Offset Adjustment
ADJUST ENT ITE S
ADJUSTING PART
REF. CLAUSE
INPUT LEVEL
REC CAL (R202), 10WB
4.3.2
ETER LEVEL
ETER CAL (R201), 47KI2B
4.3.2
REPRO LEVEL NR OFF
REP LVL NR OFF (R204), 4.7WB
4.3.3
REPRO LEVEL NR ON
REP LVL NR ON (R203), 4.7KHB
4.3.3
REPRO FREQ RESPONSE
REP EQ (R206), 4.7KI2B
4.3.4
REPRO BIAS LEAKAGE
REPRO BIAS TRAP (UI 8) 4.3.5
REC BIAS LEAKAGE
REC BIAS TRAP (U2)
4.3.5
ERASE CURRENT
T-l, ERASE LVL (R209, 10KJ2B)
4.3.6
BIAS CURRENT
T-2, BIAS LVL (R210, 10KS2B)
4.3.7
REC LEVEL
REC LVL (R207), 4.7KHB
4.3.8
OVERALL FREQ
RESPONSE
REC EQ (R208), 10KHB
4.3.9
SYNC CROSSTALK
SYNC X ' TALK ADJ (R205, 220HB) 4.3.13
This adjustment is done at our factory and must not be done at routine maintenance and
servicing. However, this adjustment is needed when replacing the DOLBY-S chip with new one
for servicing.
Objective : The following adjustment so called Dynamic Offset adjustment is necessary
in order to provide the transient response such as an attack response and a
decay response of the source signal being input to the DOLBY S NR circuit in
the optimum state as well as accurate state, in other words, put the G24S
in the recording mode with the DOLBY S NR circuit under the best dynamic
response state.
Tools required for adjustment:
Tone-burst generator (100 msec ON, 500 msec ~ 1 sec OFF)
Band-pass filter (BPF) with the corner frequencies at 20Hz and 200Hz and at least a 1 2dB/
octave roll-off characteristics.
Extension card (P/N : 8273617000 supplied from service dept.)
Adjusting screw driver (P/N : 8286020000 supplied from service dept.)
Adjusting points : R21 1, R212
Connecting and adjusting method (Refer to Fig. 4.20 below)