Power Supply; Self-Test Program, Error Messages - Philips PM 6303 Service Manual

3.12.
3.13.
Power supply
Five voltages are generated by the power supply section:
+15 V and -15 V are stabilized by the four-terminal voltage regulators 346/347 and adjusted by pot-
meters 723/727. Z-diodes 403/404 provide +5 V and -5 V for the zero-symmetrical operation of the
FET analog switches 319, 324 and 328. The fixed +5 V supply voltage for the digital circuitries is
outputted by the three-terminal voltage regulator 348.
The measuring earth for the analog and the digital circuitries have separate paths on the p.c.b. They are
interconnected at the electrolytic capacitors 570, 573 and 579.
SELF-TEST PROGRAM, ERROR MESSAGES
For simple fault finding several test programs are realized in this instrument.
Moreover faults may be detected by other or conventional methods.
Generally the voltages of the power supply should be checked at first (see table checks and adjustments).
While the self-test routine is part of the normal program, the diagnostic program must be especially
activated by closing solder link D (see Fig. 17, Unit 1).
The self-test routine is performed immediately after POWER ON. It confirms correct operation of the
basic functions. For check of the display all segments of the decimal and dimension indications, decimal
points and the equivalent-circuit symbols are shown for 3 seconds.
If a malfunction is detected an error code EO ... E3 is shown in the display field for the numerical value.
In this case equivalent-circuit symbols are not shown.
malfunction error code check position
RAM test uP 8039 HL (IC 309)
E1 measuring ranges programmable amplifier, level detector
E2 overflow counter of ADC ADC control, e.g. 1C338/1C339
E3 reference measurement analog signal path, 1C328 to 1C336