Philips LFH 0388, Service Manual

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LFH 0388/LFH 0488/LFH 0588
17
1500 Hz-output (pin 28): Produces the PRIORITY-marking frequency (325 msec.).
MUTE/40 Hz-output (pin 2): Switches on the 40-Hz oscillator IC 1d (650 msec.) and mutes
the speech signal (TS 1:1).
RHTT-SENS-input (pin 25): The RH-turntable pulses (pulse wheel) needed for the linear tape
counter are read in via this input.
+ A (ON)-input (pin 4): Is used to switch off the display automatically, if the unit remains in
STOP mode for longer than approx. 35 sec.
Output SLEEP (pin 1): 0. TS 201:0 (supply voltage switched off), Display:0.
+ RWD-input (pin 7): Used to determine the direction of the tape counter (+ RWD:1 - tape
drive is in REWIND mode; + RWD:0 - tape drive is in WIND, PLAYBACK or STOP mode).
VA-input (pin 9): Used to switch on »VA« on display (SK 70:1, IC 201-9:1).
Pin 11 to pin 22 (segments), pin 26, pin 27 (backplanes) are used to control the display
segments.
Switching on: Only feasible after RESET (IC 201-24:0) and with the marking button depres-
sed (In practice: insert batteries or connect power supply whilst keeping depressed the mar-
king button).
Display shows » - - - «
Press marking button: 40 Hz test
Display shows » 4« (for approx. 1.5 sec.)
Switch to RECORD .
40 Hz oscillator is on.
Press marking button: 1500 Hz test
Display shows »15 « (for approx. 1.5 sec.)
Switch to RECORD .
1500 Hz oscillator is on.
Press marking button: 40/1500 Hz test
Display shows »154« (for approx. 1.5 sec.)
Switch to RECORD .
40 Hz and 1500 Hz oscillator on.
Press marking button: Display test
Display shows »999, 888, 777, ……… 0« in a sequence of 5 sec.
By pressing the marking button, the test sequence starts again from the very beginning.
If the unit remains in position STOP for longer than 20 sec., it returns back automatically into
normal sleep mode.
The unit can be put into operation even with the printed circuit board being removed (no turn-
table pulses) by shorting out of C 15 (see also special »S«-mark given in the circuit diagram
and in the drawing of the components view for location). Additionally the function switch
SK 1 is to be mounted onto the PCB by using a standard screw (e.g. M 3x10) with nut. (See
also appropriate hints given on page 9.)
Hint for model LFH 0588: When the display unit is disconnected, R 44 is to be shorted out
(pin 6 and pin 9 of the display socket to be connected) to prevent continuous marking (IC 1d
active).
Service-Testmode
(LFH 0588 only)
Service-hint