Hitachi HRD-MD05 Serviceanleitung Seite 7

HRD-MD05
2. TAPE DECK SECTION
Adjustment point
P.WB.
T. 901
RECORDING LEVEL ADO.
• GNO
BIAS CURRENT ADO.
RTE2L RTXIL
DECKP.wa
FRONT PANEL
Fig. 20
Instruments to be used 2. Head azimuth adjustment
(I) Connect ACvoltmeterto TP. 9 01 orTP. 9 02 play back the
1. Audio oscillator
2. Electronic voltmeter
3. Attenuator
4. Frequency counter
o Jigs, Test and Check Tapes
I. Head mountingjig
2. 400 Hz, Dolby alignment tape
3. 10 kHz,azimuthalignment tape
3. Recordinglevel adjustment
4. 3,000Hz,tape speedalignment tape
(1) Connect ACvoltmeter t o TP.901or TP.902,Connect a
5. Mirror tape (for tape running check)
6. NORMAL tape (MAXELL UDI 90)
CHROMEtape (MAXELL UD1190)
METAL tape (MAXELL MX46)
O Positions of Knobs
(2)Perform recording andplayback a ndadjust R T901LR so
Match the positions of switches and knobs to those
shown in the tablefollowing unlessotherwisespecified.
REC level control (RV901LR) 4. Bias current adjustment
MAX
11)SetRT902LR a t aboutthe middle(coarse adjustment).
Tape select switch (S902) (Note 1)
(2) ByLO-D UDR tape,record andplayback a signal o f 400
RIF switch (S801)
Dolby NR switch (S903)
OFF
NoteI: Settapeselect switch asshownbelowaccording t o
(3) Record thesignalof 400Hzata levelof 245mV— 10dB.
the tape being used.
Tape used
Tape select switches
No tape used
NORMAL
(4) Next,usetheItemB•6tapeat—25dBlevelandmeasure
Test tape NORMAL
NORMAL tape NORMAL
5. Dolby check
CHROME tape Cr02
(1)At a recording status, a pplyasinewaveOf5 kHz to CD
METAL tape METAL
Open the cassettelid and then clean the heads,pressure
(2) Makesurethe voltagebetweenTP. 901or TP.902and
rollers andcapstans usingalcohol,thenperformadjustment
according to the following procedure.
1. Tape speed adjustment
6. CassetteChassisInspection and Adjustment
(1) Connectafrequency counterto TP.901or TP.902.With
TAPE 1playback (forward) a bout t hemiddle of testtape
No.
MTT-II 1 and adjust RT903so asto obtain 3,000 Hz± 20
Hz.
Thenmakesureof 3,000Hz± 90Hzwith TAPE 1 play
2
back (reverse) and TAPE 2 play back.
3
(2) Make sure Of 6,000 Hz ± 600 Hz when the TP903 is
4
shorted to GND.
TAPE SPEED ADO.
TP. 903
RT901R
test tapeMIT-114(10kHz)andadjustthe headangle
adjusting screw so the output is a maximum.
If L andR channelpeaksare different,retain Lchannel
peakas main (at this time, the difference in peak
betweenbothchannels must be 2 dB max.)
Performthis adjustmentfor both TAPE1 and2. After
adjustment, apply screw lock.
generatorto CDINPUT and applya sinewaveof I kHz
Setthe deckto a recording statusand adjustthe
generator output so the output at TP. 901 or TP. 902 is
245 mv — 25 dB.
the outputat TP.901or TP.902is 245mv — 25dB ± 3
dB.
Hzand a signal of 10 kHzat a level of 245 mV — 25 dB.
AdjustRT902LR sotheoutputof 10kHzis ± 1.5dBwith
respect to the output of 400 Hz.
Makesurea playedbackoutputis 245mV— 10dB ± 2
dB.
record playback frequency characteristics to confirm
that these values are within specified limits.
INPUT andadjustto 245mV— 25dB the voltage
between test points TP. 901 or TP. 902 and GND.
GNDis — 19.6dB ± 2dBwhenDOLBY switchis turnod
on.
Reference value
Inspection item
PLAY BACK
RECORD
Playback torque 27 to 60 g•cm
27 to 60 g•cm
FFIREWtorque
55 to 120 g•cm
55 to 120g•cm
Tape drive force
Over 50g Over IOOg
Supply back-tension
1.8 to 5.0 g.cm 1B to 5.0 g•cm