47
10.3. SUPPLY AND TAKE-UP SENSORS
Supply and Take-up phototransistors are used to sense the beginning and end of tape. The tapes has transparent leaders enter
the tape transport path, they allow infrared light from the sensor LED to reach either one of the tape end sensors
(phototransistor).
If the Take-up end sensor detects the light, the microprocessor SYSTEM CONTROL IC places the VCR in the Stop mode and
then performs a short Cue.
If the supply end sensor is triggered, the microprocessor activated the Stop mode and the Rewind mode.
The Rewind mode continues until that the Take-up end sensor detects the end of the tape. The tape beginning is detected by a
low signal at SYSTM CONTROL IC Supply photo terminal.
If the light is received at both sensors at same time, cassette is ejected.
10-3-1. Detection timing
Start and end edges are detected in VCR mode when capstan rotates and mechanism shifts its position. LED always lights
during power on.
10-3-2. Sensitivity of detecting the start and end edges of tape
1.
Transparent tape that has more than approx. 50% transparency according to VHS standard is detected.
2.
Tape that has less than approx. 3% transparency according to VHS standard is not detected.
10-3-3. Action after start and end edges are detected
Mode
Detection of the start
edge
Detection of the end
edge
Detection of both
edges
POWER OFF ON
SHORT CUE *1
SHORT REW *2
STOP
CASSETTE IN
SHORT CUE *1
SHORT REW *2
EJECT
LOADING
SHORT CUE *1
SHORT REW *2
STOP
PLAY/REC/CUE/FF/SLOW/STILL/ADUB/I
NSERT
--------------
AUTO REW
STOP
RPLAY/REV/RSLOW
SHORT CUE *1
---------------
STOP
REC PAUSE SHORT REW
--------------
---------------
STOP
TIMER REC/OTR
AV2PB(H) REC
--------------
SHIRT REW *2
POWER OFF
STOP or P-OFF
PLAY OFF TIMER
--------------
AUTO REW
POWER OFF
STOP or P-OFF
*1: SHORT CUE is to shift to STOP after rotating the tape until white part of tape is over. When other mode such as PLAY is set
during detecting the start edge, mode shift to the required mode after the white part of tape is wound.
*2: SHORT REW shifts to STOP or POFF after REW is performed for approx. 2 sec. in actual time.
Both ends of tape detection (tape cut, no cassette)
(1) Cassette in: The cassette tape id ejected
(2) Other mode: The unit goes to Stop mode and it is impossible to operate except eject key.
(3) Timer REC: Power is turned off after short CUE is performed.
10-4. SAFETY TAB SWITCH
A recorded video cassette tape can be protected against accidental erasure by breaking off the tab on the cassette tape. The
cassette tape can now only be used for playback. To be able to record on the cassette, cover the hole with adhesive tape. If the
safety tab on the cassette has been removed, Safety Tab Switch is off (open) and high signal is supplied to SYSTEM CONTROL
IC will not go into the recording mode and automatically place the VCR in the playback mode. If trying to set REC, ADUB or insert,
cassette mark flashes to warn.
Summary of Contents for NV-HV61GN
Page 21: ...2 REMOVAL OF THE BACK PANEL Remove 2 Screws C Remove Screw D Unlock 4 Tabs E Fig D3 21 ...
Page 29: ...10 2 CASING PARTS SECTION 29 ...
Page 30: ...10 3 PACKING PARTS SECTION 30 ...
Page 31: ...11 REPLACEMENT PARTS LIST 31 ...
Page 41: ...C4537 ECJ2VC1H560G CHIP CAPACITOR 41 ...
Page 44: ...D2002 B0AAED000003 DIODE 44 ...
Page 47: ...Q1152 2SC3311ASA TRANSISTOR 47 ...
Page 49: ...R1502 ERJ3GEYJ273V CHIP RESISTOR 49 ...
Page 54: ...W519 ERJ3GEY0R00V CHIP JUMPER 54 ...
Page 109: ...4 1 3 PARTS NAME OF R4 MECHANISM Fig M2 ...
Page 139: ...34 ...
