HP 6205B Manual de usuario descargar pdf (Pagina 34)

TM 11-6625-2965-14&P

Table 5-5. Output Voltage Troubleshooting (Continued)

Check turn on of Q3 by

shorting Q1A emitter to

collector

5-58 REPAIR AND REPLACEMENT

RESPONSE

Output voltage remains low

b. Output voltage increases

PROBABLE CAUSE

a. Q3 open

b, Check Q1A for open, QlB

for short. Check R10 for

short or open strap be-

tween A7 and A6

teristics of selected semiconductors. If the device

5-59 Before servicing a printed wiring board, re-

to be replaced is not listed in Table 5-6, the

fer to Figure 5-11. Section VI of this manual con-

standard manufacturers part number listed in Sec-

tains a tabular list of the instruments replaceable

tion VI is applicable. After replacing a semicon-

parts. Before replacing a semiconductor device,

ductor, refer to Table 5-7 for checks and adjust-

refer to Table 5-6 which lists the special charac-

ments that may be necessary.

Table 5-6.

Selected Semiconductor Characteristics

REFERENCE

SUGGESTED

DESIGNATOR

CHARACTERISTICS

STOCK NO.

REPLACEMENT

Matched differential amplifier. NPN Si. planar

1854-0229 2N291 G.E.

70 (min.) h

FE i

= lmA, VCE = 5V, Ico = 0.01µA

@ V

cbo

5V,

NPN Power hFE = 35 (min.) @ Ic = 4A; VCE = 4V.

1854-0225 2N3055 R. C,A,

Table 5-7.

Checks and Adjustments After Replacement of Semiconductor Devices

REFERENCE

FUNCTION CHECK

ADJUST

Constant voltage differential amplifier

Constant voltage (CV) line

R6 or R8

and load regulation.

Zero

volt output.

Q3, Q4 Error amplifiers CV load regulation.

R30

CV transient response.

Q7 (Q6)

Series regulater

CV load regulation.

Q8, Q9 Reference regulator

Reference circuit line

VR1, VR2,

regulation.

CR20

CR1, CR2

Limiting diodes

CV load regulation.

CR8

Forward bias regulator

Voltage across diode

2.0 to 2.4 Volts.

5-12

1 2 ... 29 30 31 32 33 34 35 36 37 38 39 ... 67 68

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