Philips CD304 MK II - Track Detector Functionality; Radial Control Functionality

Precise method
(can be checked in playing set only)
— Place test sample 5A (4822 397 30096) on turntable.
Switch power on and depress Play button.
— Select track no. 10: Check point $8.
HFLS pulses should be present.
— Select track no. 15: Check point $e).
‘DO pulses should be present. With this track the HFLS
pulses on point should also be present.
— Incase of track jumping HFLS pulses are always present
on point 6.
Sub. G. IS TRACK DETECTOR FUNCTIONING WELL?
Test method (Test points on servo PCB)
Switch off the offset circuit:
Loosen resistor 3335 (at the side where it is in contact with
pin 14 of 106215).
Mounta47 kfNtrimming potentiometer between +1 and —1
supply voltage (for example between pins 4 and 11 of
1C6215). Connect the wiper of the trimming potentiometer
to the loose side of resistor 3335.
— Place a disc on the turntable.
— Bring the set in service loop A.
— Adjust the signal on test point &> symmetrically round
OV by means of the external 47 kN. trimming potentiometer.
The amplitude of the signal may change during this
adjustment.
— Measure F.S. on point 6.
Here too the frequency variation depends on the ec-
centricity of the disc.
— Check point >.
— Check point 6). Signal cannot be triggered.
— Check point €>.
— Switch the offset circuit on again.
Sub. H. 1S THE RADIAL CONTROL FUNCTIONING
PROPERLY?
Attention: The offset circuit (d-multiplier) and the AGC cir-
cuit (k-multiplier) are correction circuits. This means that
under optimal conditions (new disc, minimum tolerances
of components) the set may be working properly even if
a fault is present in offset or AGC circuit.
Test method (Testpoints on servo PCB)
a. Place disc on turntable.
b. Switch off AGC circuit (k-muitiplier) and switch off off-
set circuit (d-multiptier).
Method:
Switching off AGC circuit: interconnect points 5 and 6 of
IC 6216.
7-5
Switch off the offsef' circuit:
Loosen resistor 3335 (at the side where it is in contact with
pin 14 of 1C6215).
Mount a 47 kQN trimming potentiometer between +1 and —1
supply voltage (for example between pins 4 and 11 of
1C6215). Connect the wiper of the trimming potentiometer
to the loose side of resistor 3335.
— Place a disc on the turntable.
— Bring the set in service loop A.
— Adjust the signal on test point > symmetrically round
0 V by means of the external 47 kQ trimming pot. The
amplitude of the signal may change during this
adjustment.
c. Bring set in service loop B.
At this moment there is a high probability that the set is
working.
If so, check b and d factor (see Annexes IV and III).
If not, proceed.
d. Bring set in service loop A and check signal on point
The AC-component has to be 12-14 V symmetrically,
around a DC level of zero volt.
If this is correct, proceed to e).
If this is not correct check following testpoints
4 €} : value should be 0.7 Vpp
: value should be 0.2 Vp
& : value should be 0.25 V,,
: value should be 20 mVpp
>, & : value should be 800 mMVpp
Note:
The frequency variation strongly depends on the ec-
centricity of the disc.
If points > = > are OK, check point > again.
Ite is OK, proceed.
e. Check point > (is RE +650 Hz).
Value should be 6 Vp. If so, proceed.
When the set is in the normal stand-by position 650 Hz at
300 mV is present on point Sd.
f. To check radial output stage, do not use a disc, only po-
wer on. Inject on points &> and > respectively a sine-
wave signal of 8 to 10 Hz 3 V,,.
Then the radial motor will go back and forth.
At this moment radial tracking must be possible in service
Joop B.
— Switch the AGC circuit on again.
If the original fault symptom is stil! present proceed to
Annex IV:
Check of the k-factor.
— Switch the offset circuit on again.
If the original fault symptom is still present, proceed to
Annex III:
Check of the d-factor.
CS 5 223GB