Harman Kardon CD491 - Troubleshooting Checklist

10
3. Playback level and playback frequency response
confirmation of REC. CAL. TONE and BIAS TONE
1) With the tape selector set at the LN position,
record the REC. CAL. TONE for more than 1
count indication of the counter. During playback,
check to ensure that one of —1VU, OVU and
+1VU on the Leh of the LED display lights.
If the display does not operate as described above,
make a readjustment by repeating step 14 of
Electrical Adjustment.
Repeat the same check with the tape selector set
to the CrO2 position and then the Metal position.
The level difference with the Rch must be within
1VU.
2) As in step 1), record the BIAS TONE by pressing
the BIAS TONE button and play it back. During
playback, keep the BIAS TONE button depressed
and check to ensure that one of —1VU, OVU
and +1VU on the Lch of the LED display lights.
If the display does not operate as described above,
make a readjustment by repeating step 14 of
Electrical Adjustment.
The level difference with the Rch must be within
vu.
4. Recording/playback frequency response correction
confirmation by means of BIAS FINE TRIM
1) With the 2ch VTVM connected to the LINE OUT-
PUT terminals and the tape selector set to the
CrO2 position, record the BIAS TONE by pressing
the BIAS TONE button and play it back. Note
the output level of Lch and Rch when playing
back and suppose it as OdB.
2) Turn the BIAS FINE TRIM all the way to the
BOOST side and confirm that the output level
changes more than +2dB. Then turn it all the
way to the CUT side and confirm that the output
Jevel changes less than —2dB.
3) Repeat the same confirmation procedure as in
steps 1) and 2) with the tape selector set to the LN
position and the Metal position respectively. The
amount of the output level change should be more
than +2dB on the BOOST side and less than —-2dB
‘on the CUT side.
5. MEMORY, AUTO REWIND, AUTO REPLAY opera-
tion confirmation
1) With the AUTO REWIND and AUTO REPLAY
switches in the OFF state, load the tape and wind
it up to the end by pressing the F.FWD key. Then
confirm that the AUTO STOP operation. The
unit must stop automatically about 2 seconds after
the tape was wound fully and the reel stopped.
2) With the AUTO REWIND switch ON, rewind the
tape (for any length) by pressing the REW key and
then play it back to the end. Then confirm that
the AUTO STOP operates about 2 seconds after
the tape was fully wound up and the reel stopped
and at the same time the REWIND operates auto-
matically.
3) With the MEMORY switch ON, wind the tape
approximately half way, press the RESET switch
to make the counter indication “0000” and wind
the tape quickly by pressing the F.FWD key (for
any length). Then press the REW. key to rewind
the tape and confirm that the tape automatically
stops somewhere between “0000” and “9999” on
the counter.
4) With the AUTO REPLAY switch ON, press the
F.FWD key to wind the tape quickly (for any
length). Then press the REW. key to rewind the
tape and confirm that the tape stops automatically
somewhere between “0000” and “9999” on the
counter and at the same time the REPLAY
operates.
5) Furthermore, press the REW. key to rewind to the
end of the tape and confirm that about 2 seconds
after the tape was fully rewound and the tape
stopped, the AUTO STOP operates and at the
same time the REPLAY operates.