Philips PM 6303 User manual

RCL meter
PM 6303
9452 063 03001
Service manual
9499 525 00911
8403 01/1
PHILIPS

Please note
In correspondence concerning this instrument, please quote the type number and serial number as given on the
type plate.
Bitte beachten
Bei Schriftwechsel iiber dieses Gerat wird gebeten, die Typennummer und die Geratenummer anzugeben. Diese
befinden sich auf dem Typenschild an der Riickseite des Gerates.
Noter s. v. p.
Dans votre correspondance et dans vos réclamations se rapportant 4 cet appareil, veuillez toujours indiquer le
numéro de type et le numéro de série qui sont marqués sur la plaquette de caractéristiques.
Important
As
the
instrument
is
an
electrical
apparatus,
it
may
be
operated
only
by
trained
personnel.
Maintenance
and
repairs
may
also
be
carried
out
only
by
qualified
personnel.
Wichtig
Da
das
Gerat
ein
elektrisches
Betriebsmittel
ist,
darf
die
Bedienung
nur
durch
eingewiesenes
Personal
erfolgen.
Wartung
und
Reparatur
diirfen
nur
von
geschultem,
fach-
und
sachkundigem
Personal
durchgefiihrt
werden.
important
Comme
I'instrument
est
un
équipement
électrique,
le
service
doit
@tre
assuré
par
du
personnel
qualifié.
De
méme,
I’entretien
et
les
réparations
sont
A
confier
aux
personnes
suffisement
qualifiées.
(c)
Philips
GmbH
—
Hamburg
—
Germany
—
1984
All rights are strictly reserved.
Reproduction
or
divulgation
in
any
form
whatsoever
is
not
permitted
without
written
authority
from
the
copyright
owner.
Issued by Philips GmbH -Unternehmensbereich Elektronik fiir Wissenschaft und Industrie- Werk fir MeBtechnik
Printed in Germany

0-3
CONTENTS
1. SAFETY INSTRUCTIONS
1.1. Safety precautions
1.2. Caution and warning statements
1.3. Symbols
1.4. Impaired safety-protection
1.5. General clauses
2. OPERATING PRINCIPLE
2.1. Description of the block diagram
2.2. Measuring principle
Fig. 1 One single measurement
Fig. 2 One measurement cycle
Fig. 3 Block diagram
Fig. 4 Front view
3. CIRCUIT DESCRIPTION, FAULT FINDING, with figs. 5 -13
3.1. Crystal clock, frequency divider,phase selector
3.2. Component connection, buffer, inverting amplifier
3.3. Current to voltage converter
3.4. Programmable amplifier
3.5. Band-pass filter 2
3.6. Level detector
3.7. Phase sensitive rectifier
3.8. Analog to digital converter, ADC
3.9. Central processing unit, CPU
3.10. Parameter selection
3.11. Liquid-crystal display, LCD
3.12. Power supply
3.13. Self-test program, Error messages
3.14. Diagnostic program
4. ACCESS TO PARTS
4.1. Dismantling the cabinet
4.2. Unit 2: display unit
4.3. Pushbuttons
4.4. Carrying handle
5. PERFORMANCE CHECK
5.1. General information
5.2. General functional test
6. CHECKING AND ADJUSTING
6.1. General information
6.2. Recommended test equipment
6.3. Table of checks and adjustments
1-1
1-1
1-1
1-1
1-1
2-1
2-2
2-3
2-3
2-4
2-4
4-1
4-1
4-1
4-1
5-1
5-1
6-1
6-1
6-2

7.1.
7.2.
7.3.
7.4.
8.1.
8.2.
8.3.
8.4.
Fig.
Fig.
Fig
10.
11.
15
16
.17
Fig.
18
0-4
SAFETY INSPECTION AND TESTS AFTER REPAIR AND MAINTENANCE
IN THE PRIMARY CIRCUIT
General directives
Safety components
Checking the protective earth connection
Checking the insulation resistance
SPARE PARTS
General
Static sensitive components
Handling MOS devices
Parts list
FIGURES 15 - 18
Handle: spare parts
Mains cable: spare parts
Unit 1, Unit 2: component lay-outs
Unit 1, Unit 2: circuit diagrams
CODING SYSTEM OF FAILURE REPORTING FOR QUALITY
ADDRESSES FOR SALES AND SERVICE
7-1
7-1
7-1
7-1
8-1
8-1
8-1
8-2

1.1.
1.2.
1.3.
1.4,
1.5.
1.5.1.
1.5.2.
1.5.3.
1.5.4.
1.5.5.
1.5.6.
SAFETY INSTRUCTIONS
WARNING:
These servicing instructions are of use by qualified personnel only. To reduce the risk of electric shock,
do not perform any servicing other then that specified in the Operating Instructions unless you are fully
qualified to do so.
Read these pages carefully before installation and use of the instrument.
‘The following clauses contain information, cautions and warnings which must be followed to ensure
safe operation and to retain the instrument in a safe condition.
Adjustment, maintenance and repair of the instrument shall be carried out only by qualified personnel.
SAFETY PRECAUTIONS
For the correct and safe use of this instrument it is essential that both operating and servicing personnel
follow generally-accepted safety procedures in addition to the safety precautions specified in this manual.
Specific warning and caution statements, where they apply, will be found throughout the manual.
Where necessary, the warning and caution statements and/or symbols are marked on the apparatus.
CAUTION AND WARNING STATEMENTS
CAUTION:
Is used to indicate correct operating or maintenance procedures in order to prevent damage to or de-
struction of the equipment or other property.
WARNING:
Calls attention to a potential danger that requires correct procedures or practices in order to prevent
personal injury.
SYMBOLS
C) Protective earth (black)
(grounding) terminal
IMPAIRED SAFETY—PROTECTION
Whenever it is likely that safety-protection has been impaired, the instrument must be made inoperative
and be secured against any unintended operation. The matter should then be referred to qualified
technicians.
Safety protection is likely to be impaired if, for example, the instrument fails to perform the intenced
measurements or shows visible damage.
GENERAL CLAUSES
WARNING:
The opening of covers or removal of parts, except those to which access can be gained by hand, is likey
to expose live parts and accessible terminals which can be dangerous to live.
The instrument shall be disconnected from all voltage sources before it is opened.
Bear in mind that capacitors inside the instrument can hold their charge even if the instrument has bein
separated from all voltage sources.
WARNING:
Any interruption of the protective earth conductor inside or outside the instrument, or disconnection
of the protective earth terminal, is likely to make the instrument dangerous.
Intentional interruption is prohibited.
Components
which
are
important
for
the
safety
of
the
instrument
may
only
be
renewed
by
componerts
obtained
through
your
local
Philips
organisation
(see
also
chapter
8).
After repair and maintenance in the primary circuit, safety inspection and tests, as mentioned in chapier”
8, have to be performed.

2.1.
2-1
OPERATING PRINCIPLE
DESCRIPTION OF THE BLOCK DIAGRAM, Fig. 3
The 16 MHz crystal clock generates the basic frequency for all signals, so the count pulses for the
analog to digital converter ADC.
The frequency divider generates the 8 MHz clock pulse for the microprocessor and the 1 kHz test fre-
quency in 3 reference phases, namely 0°, 90° and 180°.
In the phase selector the CPU selects the appropriate reference phase 0°, 90° or 180° for the phase
sensitive rectifier and the ADC.
The band-pass filter 1 converts the TTL signal into a 1 kHz sine wave signal.
The test voltage amplifier _amplifies i the 1 kHz sine wave signal to a 2 Veff open circuit voltage at the
component under test (CUT) connection. In the ‘Cs biased’ mode 2 Vdc are added to the 1 kHz signal.
‘ The isolating buffer senses the voitage at the CUT.
The inverting amplifier feeds a compensating current via capacitor C (90° phase shift) into the current
to voltage converter input for equalizing the stray capacitances. The amplitude of the compensating
current is set by Co TRIM.
The current to voltage converter converts the current through the CUT into a proportional voltage.
The conversion factor can be switched by a factor of 10.
For current or voltage measurement the input of the subsequent differential amplifier is switched
over by the voltage/current (V/l) selector controlled by the CPU.
In the programmable amplifier gain factors x0.1, x1 or x10 are selected by the CPU depending on the
impedance of the CUT. For the reference measurement the input is short-circuited.
The 1 kHz band-pass filter 2 suppresses hum interference and reduces the harmonic components of the
1 kHz measurement signal.
The level detector compares the output voltage of band filter 2 with a preset reference value. If this
value is exceeded, the CPU switches the programmable amplifier to a lower gain factor.
The phase sensitive rectifier generates dc voltages which are proportional to that component of the
measuring voltage being in-phase with the reference voltage.
The analog to digital converter ADC converts the output signal of the rectifier into a binary number
which can be processed by the CPU.
The central processing unit CPU with the inherent microprocessor controls and monitores the measu-
rement process, computates and stores the measurement values and transfers the result to the display.
The LCD control transforms the serial data transmitted by the CPU into parallel data and contrds
the liquid-crystal display which operates in duplex mode.
In the LED control the parameter key actuations are verified and processed. The selected parametr
is indicated by a LED. Simultaneously the information is BCD-coded and sent to the CPU, whereby
the
most
significant
bit
directly
switches
on
the
2
Vdc
voltage,
when
the
parameter
Cs
(2
V
Bias)
is
set.
The
power
supply
generates
the
required
stabilized
de
voltages
+15
V,
-15
V
and
+5
V
for
the
circuitrie.

2.2.
2-2
MEASURING PRINCIPLE, Figs. 1, 2, 3
The
measurement
principle
is
based
on
the
so-called
current
and
voltage
measurement
technique:
the
component
voltage
and
after
that
the
component
current
are
measured.
The
measured
values
are
con-
verted
to
binary
numbers.
From
these
numbers
the
CPU
computes
the
CUT
parameter
of
interest.
According
to
the
front
panel
parameter
selection,
either
the
dominating
component
—resistance,
capa-
citance
or
inductance—
or
one
of
the
other
selectable
parameters
is
displayed.
Each
measurement
cycle
lasts
approx.
0.5
s.
it
comprises
5
single
measurements,
the
results
of
which
are
stored
in
the
microprocessor
data
memory,
a
subsequent
arithmetic
evaluation
and
a
final
transfer
of
the
result
to
the
display.
The
5
single
measurements
are
as
follows:
1. Reference measurement:
At
the
beginning
of
each
measurement
cycle
a
reference
measurement
is
performed,
with
the
input
of
the
programmable
amplifier
short-circuited,
caused
by
low
signal
at
pins
27,
28
of
the
microprocessor
309.
The
programmable
amplifier
is
set
to
gain
x.1.
After
a
delay
time
of
50
ms
for
each
of
the
5
single
measurements,
necessary
for
settling
of
the
zero
control
and
the
band-pass
filter
2,
a
measurement
without
1
kHz
signal
is
performed,
comprehending
all
failures
within
the
signal
path
from
FET
switch
328
to
the
A/D
converter.
The
counter
contents
of
the
A/D
conversion
at
the
end
of
this
measurement
serves
as
reference
for
the
subsequent
4
measurements.
2. 0° voltage measurement:
The voltage at the CUT is measured.
The switching phase of the phase sensitive rectifier is O°.
For
voltage
sensing
at
the
CUT
the
inputs
of
the
differential
amplifier
are
connected
via
the
V/\
selector,
FET
switch
324,
to
the
measurement
input.
This
is
achieved
by
low
signal
of
the
microprocessor
309.30.
The
0°
switching
phase
is
activated
by
low
signal
309.33.
The
gain
of
the
programmable
amplifier
is
set
to
x.1.
After
5
ms
settling
time
for
the
1
kHz
signal
amplitude
the
output
of
the
level
detector
is
sensed,
INT,
309.6.
If
no
overrange
is
detected
—correct
for
the
100
kQ
resistor
in
our
example—
the
gain
is
set
to
x1;
the
level
detector
is
sensed
again.
As
now
overrange
is
detected
the
gain
is
set
back
to
x.land
anA/D
conversion
is
started,
309.31.
For
low-ohmic
CUTs
the
gain
is
set
to
maximum
gain
x10
and,
if
no
overrange
is
detected,
the
measurement
is
performed.
3. 90° voltage measurement:
The voltage at the CUT is measured.
The switching phase of the phase sensitive rectifier is 90°.
The
gain
of
the
programmable
amplifier
is
not
altered
with
respect
to
the
0°
voltage
measurement.
An
A/D
conversion
is
performed.
4. 0° current measurement:
The
inputs
of
the
differential
amplifier
are
switched
over
to
the
output
of
the
current
to
voltage
conver-
ter.
;
The current through the CUT is measured.
The switching phase of the phase sensitive rectifier is 0°.
The gain of the programmable amplifier is set to.x.1 and, as for voltage measurement, increased to x1
with regard to the level detector. Next, if necessary, the conversion coefficient of the I/V converter
is increased from x1 to x10 (high at 309.30) and —as valid for our example with a 100 k& resistor—
the gain of the programmable amplifier is increased to x10 and set back to x1 after overrange detection.
An A/D conversion is performed.
For low-ohmic components a slightly different sequence is performed: If for voltage measurement
the gain was set to x1 or x10, the impedance is in any case very low, resulting in maximum current to
flow. The current measurement is performed at gain x.1 without trial for gain changing.

5. 90° current measurement:
The current through the CUT is measured.
The switching phase of the phase sensitive rectifier is 90°.
The
gain
of
the
programmable
amplifier
is
not
altered.
A
final
A/D
conversion
is
performed.
At
the
end
of
the
5
single
measurements
the
5
corresponding
binary
numbers
of
the
A/D
conversions
and
the
assigned
gain
factors
are
stored
in
the
microprocessor
data
memory.
From
this
the
micropro-
cessor
first
calculates
the
equivalent
series
resistance
Rs,
the
equivalent
series
reactance
Xs
and
the
quality
factor
Q
=
Xs/Rs
of
the
CUT.
In
the
RCL
AUTO
mode
the
microprocessor
determines
the
dominant
component,
either
Rs
resp.
Rp,
Cp
or
Ls,
calculates
its
value,
dimension
and
equivalent-
circuit
symbol
by
arithmetic
routines
and
transfers
the
result
to
the
display.
If
one
of
the
8
other
para-
meters
is
selected
by
the
step
keys
this
parameter
is
calculated
and
displayed.
After
that
the
micropro-
cessor
starts
the
next
measurement
cycle
with
the
single
measurement
routines.
For
fault
finding
the
5
single
measurements
can
statically
be
controlled,
performed
by
the
diagnostic
program,
see
chapter
3.14.
= 0°/90° VII gain delay time A/D con- storage in
selection setting 50 ms version data memory
Fig. 1 One single measurement
Xs, Rs, Q data for-
computation parameter value matting
& averaging verification computation & transfer to
displa
Fig. 2 One measurement cycle (ca. 0.5 s)

phase
selector
90°
416 MHz frequency band-pass
crystal divider filter 1
clock TkHz 1 kHz
GUARD
8 MHz 1/select ¥ 17 DC bias
to CPU on /off
+15V -15V +5V
power
supply
6) Cs (2V BIAS)
4 LED
control
1 U2 parameter
selection
CPU
central processing unit
L___-4 @ RcLauTo
-
t
| a display
curr. to volt. band-pass 33] csbay
converter
fitter
2
sensitive
pie
&
=U
pF
\
ei,
ee
x1
/x1/x10
1kHz
rectifier
U2
83
u2
|
|
|
843
34
clock,
load,
-~@
RCL
AUTO
a
—
level
QQ
|
1
gain,
detector
11—~
data
from
®
0
4
1
inhibit
for
counter
=
SENSE
|
—
+
SENSE
&
Rp
;
;
BIAS
ref.
meas.
-
overrange
5
|
carry
from
QRs
i!
|
counter,
end
S
jit
'
2
of
integr.
OZ
L—-
asc
;
©
Cp
or
Lp
|
integration
®Cs
ork
component
under
test
start
/reset
S
rks
{
|
t
t
{
1
POWER} - -/-- = 4 A step up
Sane @ TRIM hee Sa -\ v step down
Fig. 3 Block diagram
Le
PM 6303 REL m BHILIPS
Fig. 4 Front view

3.1.
CIRCUIT DESCRIPTION, FAULT FINDING
CRYSTAL
CLOCK,
FREQUENCY
DIVIDER,
PHASE
SELECTOR
The
accuracy
of
the
16
MHz
clock
frequency
is
moderate,
+5-
10°75.
So
fixed
load
capacitances
506,
504
are
inserted;
they
nevertheless
may
be
altered
in
test,
if
necessary.
The
output
of
the
oscillator
is
decoup-
led
by
inverter
307/2.
307/1
feeds
the
16
MHz
count
pulses
for
the
analog
to
digital
converter
ADC.
The
first
divider
stage
of
the
4-bit
binary
counter
308
generates
the
8
MHz
clock
pulse
for
the
micro-
processor.
Its
last stage
feeds
1 MHz
to
the
frequency
divider
chain.
1C
306
comprises
two
4-bit
BCD
counters,
the
5
:
1
division
of
which
is
used
for
dividing
the
frequency
down
to
40
kHz.
Further
division
by
10
results
in
a
4
kHz
signal
at
output
304.9,
the
basic
frequency
for
generation
of
the
1
kHz
signals
with
different
phase
relations,
see
fig.
5
.
The
trailing
(high
to
low)
edges
trigger
the
J—K
flipflops
303,
302.
The
1
kHz
signal,
phase
0°,
is
fed
to
the
band-pass
filter
1.
At
the
output
4
of
the
multiplexer
301
a
0°
or
90°
signal
is
available,
selected
(‘select
y’)
by
the
microprocessor.
At
output
7
a
signal
shifted
by
90°
with
relation
to
pin
4
is
available
for
synchronisation
of
the
analog
to
digital
converter
ADC.
eV
ee
ee
ae
fr
|
!
| | |
SOG
tee
ee
ee
| { |
| | |
G2
aes
el
ee
|
|
302/15
Sima
sete
re
i
eer
1
kHz
{
|
{
|
|
302/1.6
a
he
i
|
Ce
ee
ereearaa
(Se
Sane
——w}
250s
|
ego
Ims
Fig.5 Generation of the 1 kHz signals