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Troubleshooting Tree - HP 465A Operating And Service Manual

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Section V
Figure 5-4 and Table 5-5
465A-B-0218
Remove the + side of C14 from the circuit
board.
Set Model 465A GAIN to 40 db.
Apply a 1. 0 mv, 2 kc input signal.
Measure the de voltage at the + side of C20.
Should be +45 v (±1 v). If corre
<ID
;
if incorrect, go directly to
Observe the ac waveform at the Model 465A
OUTPUT. Should be a sine wave with peak
voltage of approximate
incorrect, proceed to
Observe the ac waveform at the base of Q4.
Should be a sine wave with peak voltage of
approximately 12.7 v (9 v rms).
®;
proceed to
if incorrect, go directly to
@.
Observe the ac waveform at the junction of R24
and R25. Should be a sine wave with peak
voltage approximatel x... 12. 7 v (9 v rms). If
correct, proceed to
(1) .
to
@
Check R26, R27 and C15.
5-6
FALSE
FALSE
TRUE
TRUE
FALSE
Figure 5-4. Troubleshooting Tree
Table 5-5. Troubleshooting
proceed to
12.7 v (9 v rms). If
If correct,
;
if incorrect, go directly
11
10
FALSE
FALSE
TRUE
TRUE
Check Q4, Q5 and Q6. Refer to Figure 5-8
for typical de voltage levels.
Check Ql, Q2 and Q3.
Refer to Figure 5-8
for typical dc voltage levels.
Disconnect jumper wire at the + side of C20,
removing power supply from circuit. Measure
dc voltage at the + side of C20. Sho
+45 v(±1 v). If correct, proceed to
incorrect, go directly to
Connect a DC Power Supply (-hp- Model 723A)
to the collectors of Q5 and Q6. Connect the
high side to the collector of Q5; the low side
to the collector of Q6.
supply output to +45 v; set current limit to
75 ma. If power supply indicates current
limit, check Q4, Q5, Q6 and CR2-3 for short.
Check Model 465A power supply to include Tl
secondary, Q7, CR6, Q8 and Q9.
Figure 5-8 for typical dc voltage levels.
Model 465A
be
;
if
@ .
Adjust the power
Refer to
01775-1

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