Checking And Adjusting - Philips PM 5125 Manual

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Checking and adjusting
The tolerances mentioned in the following text apply only to newly
adjusted instruments. The values may differ from those given in chapter 11,
TECHNICAL DATA.
For optimum performance the instrument should be adjusted at the
temperature at which it will be used.
The adjusting elements and the auxiliary equipment required for the
adjusting procedure are indicated in chapter X.
A. GENERAL
The circuit should be earthed by connecting BU6 to BU7. All test
equipment should be earthed via the instrument under test.
Accurate checking and adjusting of the frequency and the distortion
according to sections D and G is only possible when the covers are
fitted on the instrument and after a warming up period of at least twenty
minutes.
B. MAINS CURRENT
Connect the instrument to the mains and check that the current con-
sumption does not exceed 150 mA at 230 V mains or 300 mA at 115 V
mains.
C. SUPPLY VOLTAGES
- Remove the printed wiring board of the oscillator and that of the
squarer/amplifier.
- Check that the voltage between points CD3/9 and CD3/11 is —30 V
f 0.5 V. Adjusting elements: R249.
- Check that the voltage between points CD3/11 and CD3/14 is +30 V
~ 0.5 V. Adjusting element: R252.
- Refit the printed wiring boards.
D. FREQUENCY
1. -Set the trimmers R40, R42, R45, R52, C25 and C27 to the mid
position and turn C35 completely out.
- Set switch SK3 to position x 102
- Set switch SK2 to position ~.