HP 400D, Инструкция по эксплуатации и обслуживанию

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Sect.
IV
Page 12
TABLE 4-2.
TROUBLE SHOOTING CHART (CONT'D)
Symptom
Possible Cause and/or Remedy
Microphonics (Cont'd. )
If
instrument seems to be equally microphonic on
the 0. 3 volt range with 0 . 3 volt input, change
V2.
If
instrument is less microphonic on the
0. 3 volt range, replace VI.
Poor electrical contact in range switch.
Clean and
inspect switch contacts.
Use a cleaning solvent
that will not leave a deposit.
Do not disturb
wires.
Check all solder connections.
Loose or imperfect
jOints will appear as microphonics.
V3, V4, and VS may also cause microphonicB.
Response at 10 cps is low or high.
One or more weak tubes (try V3 and V4 first), de-
fective coupling capaCitor (CIB, Cl9, etc. ),
or
defective cathode by-pass capacitor (C20,
etc).
Response at 4 mc low.
Weak tubes (VI through VS).
Motorboating.
Motorboating may be caused by low voltage from
the regulated power supply, Or from low ac line
conditions.
Weak V2, V3, V4,
VS (see paragraph 4-10 to lo-
cate trouble).
Trouble in power supply (see paragraph 4-9).
High plate or screen voltage for V2, V3, V4, and/
Weak or defective tube.
Refer to paragraph 4-10.
or VS.
Open cathode resistor.
Low plate or screen voltage for V2, V3, V4, and/ Defective grid coupling, cathode, or screen by-
or VS.
pass capacitor. Refer to paragraph 4-10.
Defective tube.
Voltmeter reads high Or low on two voltage ranges
Defective range switch component(s). Correct by
that are multiples of 1000 apart.
replacing entire range switch assembly.