HP 203A - Square Wave (A8 and A9); 5-26. Troubleshooting; Troubleshooting Summary

C
C
Model 203A
Note
Do not place DC Amplifiers (A6 and АТ) on ex-
tender board.
g. Set REFERENCE PHASE ~ AMPLITUDE for AC
voltmeter reading of 4. 9 vac.
DO NOT EXCEED 7.5 MV OUTPUT AS THER-
MAL CONVERTER 1$ VERY EASILY DAMAGED
BY EXCESSIVE INPUT VOLTAGE.
h. Disconnect AC Voltmeter.
i. Carefully adjust REFERENCE PHASE ~ AM-
PLITUDE for a DC Voltmeter reading of 7. 0 millivolts.
К. Set Model 203A MULTIPLIER switch to 1.
т. Adjust A3R20 (A3R34 for VARIABLE PHASE)
(50 cps adj) until the DC Voltmeter reads 7.0 milli-
volts.
n. Set MULTIPLIER switch to 10. Note DC Volt-
meter reading.
р. Set MULTIPLIER switch to ІК.
ч. Adjust A4R2 (A5R2 for VARIABLE PHASE)
(50 ke adj) until DC Voltmeter reads the same as іп
step j.
г. Repeat steps | thru q until readings at 50 eps,
900 eps and 50 kc are between 6.93 and 7.07 milli-
volts.
S. Repeat steps a thru r for the VARIABLE
PHASE - OUTPUT.
t. Disconnect Thermal Converter and connect
AC
VTVM
to
REFERENCE
PHASE
~
OUTPUT
terminals.
Set
REFERENCE
PHASE
~
AMPLITUDE
fully clockwise.
u. Adjust A6R20 (A7R20 for VARIABLE PHASE)
AMP. Adj for 10. 6 volts.
v. Repeat steps t and u for the VARIABLE PHASE
. ^ OUTPUT.
3-24.
PHASE
LAG
DIAL.
a. Connect Model 203A as shown in figure 5-6.
01760-3
fully clockwise.
Section V
Paragraphs 5-24 to 5-29
b. Set FREQUENCY dial to 10;
switch to 100,
MULTIPLIER
Set
both
~
AMPLITUDE
controls
.
c. Adjust PHASE LAG dial and one (not both) of
the
~
AMPLITUDE
controlsfor
minimum
reading
on
AC
Voltmeter.
Typical
reading
is
less
than
50
mv.
d. Loosen set screws and slip PHASE LAG dial
until
it
reads
exactly
180°
at
the
null
obtained
in
step
с and then tighten the set screws.
Note
If a phase error is noted at different points on
the dial, it may be necessary to slip the dial
in order to minimize any errors.
5-25. SQUARE WAVE (A8 and A9) ADJUSTMENT.
a.
Connect
DC
Voltmeter
to
Model
203A
REFER-
ENCE
PHASE
Jl,
OUTPUT.
b. Set Model 203A controls as follows:
ЕҢЕОПЕЧСҮ................ 10
MULTIPLIER: и. „лш ушж жеш. 100
-;АМРМТООЕ
ссу
уж
ыз
both
CW
c. Adjust A8R9 for a minimum reading onde volt-
meter (typically between +50 and -50 millivolts). (See
figure 5-17.)
Я. Connect de voltmeter to VARIABLE PHASE
OUTPUT.
e. Adjust A9R9 for a minimum reading on dc
voltmeter (typically between +50 and -50 millivolts).
5-26. TROUBLESHOOTING.
5-27. To locate trouble in the Model 203A, start
with a thorough visual inspection of the instrument.
Look for burned out or loose components and con-
nections, and other similar conditions which suggest
a source of trouble. For further aid introubleshoot-
‚ ing use Model 203A Block Diagram (figure 4-1),
Purpose for Factory Selected Values (table 5-5),
Troubleshooting Summary (table 5- 6), and Typical
Waveforms (figure 5-7).
5-28.
PRINTED
CIRCUIT
BOARD
REPAIR.
5-29. The Model 203А uses plated through doubles 20
Sided etched circuit boards.
9-9