Philips CD304 MK II - Page 41

Annex III: CHECKING d-FACTOR
(Test points on servo PCB)
— Switch off AGC circuit (k-multiplier) and switch off
offset circuit (d-multiplier). See sub G and H.
Place
disc
on
turntable
and
set
player
in
service
loop
A.
— Check points > and >.
Value should be 0,7 Vp.
Frequency variation strongly depends on the eccentri-
city of the disc.
— Check point @.
Value should be 250 MV pp.
— Check point >.
Value should be 200 MVpp.
— Check point $e.
Value should be 2 V,p.
— Check points > and .
Value should be 10 V,p.
The signal is more sine-shaped now due to filtering out
of 650 Hz.
—
Point
&>
is
hard
to
measure
since
switch
is
in
position
Yoc and thus connected with input of op-amp 6215.
However, a signal of 200 mV,, is present.
— Check point a.
Value should be 9 Vpp.
Bring
the
player
in
service
loop
B.
With
a
disc
on
turntable
and the AGC and offset-circuits are still switched off.
— Check point &}.
— Check point > on beam A of oscilloscope and check
point & onbeam B of oscilloscope while oscilloscope
is triggered with point @).
— Switch on the AGC-circuit and the offset dircuit.
Annex IV: CHECKING k-FACTOR
(Test points on Servo PCB)
a. Static
Switch power on without depressing the Play button.
l.e. RCO = high; RCO = low so switch Y, is in position 0
and switch Y, is in position 0.
— Check point @>.
Value should be 9 Vp).
— Check point @>.
— Onpoint &> now appears a sine-wave signal of 650 Hz,
300 mV, and 180 - 45 = 135° shifted in phase relative to
signal on point @.
— Check point @p.
Value should be 1,5 V,,.
— Check point @.
Value should be 1 Vpp.
— Check points @, $, $> and 4 relative to each
other.
Amplitudes are 5V.
— Check integrator IC 6212A.
CS 5 227 GB