Philips 900 Series - Product Lifecycle Management; Storage and Replacement; Disposal and Battery Removal

CIRCUIT DESCRIPTION
2.1.2 Handling DCC-Head
CAUTION: Each head-device is suspectable
to electrostatic voltage higher than 150Vdc!
The head is protected against external
electrostatic charging by connecting the head
flexible cable to the read/write board.
Before disconnecting the cable, always place
the deck on a bench with required
electrostatic discharging measures taken and
wear electrostatic discharging band.
Moreover, always mount the short-clip on the
flexible cable removed. See figure 7. Action
G3.
Fie. 7. Detarle af loosening head flerthle cable.
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The head is also suspectabie to strong
external magnetic fields and the analog
output may be affected.
DO NOT USE HEAD DEMAGNETIZER,
MAGNETIC SCREWDRIVER OR
DEMAGNETIZER CASSETTE!
Also in figure 7 the way how to loosen the
head flexible cable is shown by action G1 u/i
G3.
Pay attention to connector 1800. The fixation
part of the connector, which will be moved by
action G1, should be shifted over a very smail
distance. Otherwise the detentions of that part
are destroyed.
PHIJ?S SOUND & VISION, BG AUDIO - Service Training
19
2.2 Command gearwheel
2.2.1 Moving headsupport
All mechanical positions of the headsupport
are achieved by the flywheel rotation (item
108). The gearwheel on this flywheel drives
the command gearwheel (item 111) which
positions, via cams at the bottomside, bracket
item 507 (explanation follows). Via the cam
on the top side (see exploded view, figure 5;
item 111), the headsupport assembly item
117 is moved. By turning the command
gearwheel the headsupport assembly (via a
bent part of support-bracket 117A) is driven
inside. By this movement the headsupport
with head and pinch rollers are also moved
towards tape and capstan. Dependant on the
position of bracket 507 the left or the right
pinch roller, by means of corresponding pinch
roller spring, indicated with 504, is pressed
against its capstan.
Is the bracket 507 near to the left pinch roller
(item 102), spring 504 hooks onto the bracket
of that roller and moves the roller against the
capstan (item 108). In that position of 507 the
right-hand spring 504 misses the hook of
bracket 118, when head support assembly is
moved inside, so the right-hand pinch roller
does not come against capstan 126. Is
bracket 507 moved to the right-hand
pinchroller than that roller is brought against
the capstan and than the opposite left roller
will be free.
Also the cog {item 502) has been moved by
item 507. This cog rotates via item 501C the
head. With this movement the “forward” and
"reverse" head positions are obtained.
The release of the command gearwheel is
done by solenoid coil L101 with bracket item
112. Both positioned at the bottom side of the
tape deck mechanism. For the timing of the
solenoid pulses see Control timing charts
paragraph 3.3.3.
2.2.2 Stop position
in figure 8 the Stop position of the gear wheel
is shown. When L101 is activated, bracket
112 will no longer block gearwheel 111, but
move this gearwheel a little bit
counterclockwise and than it snaps into the
capstan gearwheel. If the solenoid is
activated the guiding pin of item 507 will
come into the FWD mode (forward). See
figure 9.
PHILIPS SOUND & VISION, BG AUDIO - Service Training
CIRCUIT DESCRIPTION
1$52DB
Fig. 8. Command gearwheel in Stop mode.
2.2.3 Play Forward position
PLAY FORWARD Berg
Fig. 9. Command gearwheel in Play Forward.
The gearwheel! is driven by the capstan
gearwheel approximately for 3/4 quarter part
to the first following open part in the
gearwheel and there it stops and item 112
blocks the gearwheel. The guiding pin of
bracket 507 is driven into the mid track on
command gearwheel 111. The mechanism is
in Play forward mode. Via the force of spring
503 the head support assembly is pressed
against the cam on top of the command
gearwheel. In case the solenoid is activated
in Play mode the command gearwheel will be
released and bracket 112 slaloms through the
mid opening (search position) forced by
spring 503, until the command gearwheel
reaches the stop position and is blocked
again.
PCS 83 519