Philips PM6302 Instruction Manual page 38

38
3.5.2.4. Q/D potentiometer
— Turn the Q/D potentiometer to left-hand stop
— Check that the mark on the contra! knob coincides with the mark on the text plate
— Connect to sockets | and E a circuit as indicated below (fig. 19) in order to adjust resistor 712A.
Ri Ct = 100 nF 41% tangd <2.10-4
re e1 E Rt = 237 2+ 1 % metal film MR25
IA ee R2=7.15kQ# 1 % metal flim MR25
Magazs Fig. 19. Adjusting circuit for resistor 712A
— Depress button C (button D not depressed)
— Set range switch to position x10 nF
— Set control D/Q to position 14
— Adjust capacitive components to a minimum
— Adjust bridge to minimum scale deflection with resistor 633
— Connect to sockets | and E a circuit as indicated below (fig. 20) in order to adjust resistor 712B +
R3 C1 = 100 nF £ 1% tang.6 <2,10-4 i
I
ci
3
R3 = 23.7 kQ.+ 1 % metal film MR25
{
et-+ R4 = 750 kQ + 1% carbon CR26 j
Rg
Fig. 20. Adjusting circuit for resistor 712B i
MABEZE
-~ Fallow the same procedure as described for adjustment of resistor 712A, exept the following two points
— Depress button D
— Adjust bridge to minimum scale deflection with resistor 632
3.5.3. Testing the bridge functions H
— Depress button R
3.5.3.1, Range-resistor check i
— Connect for each range a resistor to sockets I-E with a value of 10x the corresponding range indication.
Resistor tolerance: < 0.1 %.
Example: range = x1 k —— value 10 x 1= 10kQ+0,1%
— Now the bridge must be tuned for each range position
— Note the measured results. The difference between the measured results and the sample values should be <1 %, 7
3.8.3.2. Linearity check of the scale potentiometer
— Set range switch to position x1 kQ
— Connect standard resistors from 1 kQ to 10 kQ in steps of 1 k& to sockets I-E
— Tune the bridge for each step and check that the resistance reading does not deviate more than the
specificied value.
3.6.3.3, Indicator check 7
— Set range switch to position x1-k@
~ Connect a 10 k&Q-resistor to sockets I-E
— Tune the bridge
— If detuning the bridge one scale division, the deflection of the indicator should be > 0.2 scale division
— Depress button SEARCH
— If tight, the indicator pointer points to the lower end of the marked range
— Set range switch to position x10 kQ i
— If right, the indicator pointer points to the high r end of the marked range.
— Depress button L.
— Set range switch to position x1 mH
— Connect a coil of 10 mH to socket I-E {limits for quality factor Q of this coil: between 3 and 6} i
— Depress button Q i
— Tune the bridge
~— Depress button SEARCH; if right, the indicator pointer points te the higher end of the marked. range
— Set range switch to position x10 mH
— lf right, the indicator pointer now points te the lower end of the marked range