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7. Clip off any excess leads that protrude through the
hole in the board.
8. If necessary, clean the area around the soldered con-
nection with a flux-remover solvent to maintain good envi-
ronmental characteristics,
Replacing Components on Metal Terminals
When soldering metal terminals (e.g., switch terminals,
potentiometers, etc.) ordinary 60/40 solder is satisfactory. The
soldering iron should have a 40- to 75-watt rating and a
1
/
8
inch chisel tip.
1. Apply only enough heat to make the solder flow freely
and form a good electrical connection. Excess solder may
impair the operation of the circuit or cover a cold solder
joint.
2. Clip off excess wire that may extend past the soldered
connection and clean with flux-remover solvent,
Removing and Replacing Switches
Single wafers on the VOLTS/DIV or DISPERSION-COUPLED
RESOLUTION switches are not normally replaced. If any of
these wafers are defective, the entire switch should be
replaced. It can be ordered through your Tektronix Field
office, either unwired or wired, as desired. Refer to the
Electrical Parts List to find the unwired or wired switch part
numbers.
C A U T I O N
W h e n d i s c o n n e c t i n g o r c o n n e c t i n g l e a d s t o a
w a f e r - t y p e s w i t c h , d o n o t l e t s o l d e r f l o w a r o u n d
and beyond the rivet on the switch terminal. Exces-
s i v e s o l d e r c a n d e s t r o y t h e s p r i n g t e n s i o n o f t h e
contact.
T R O U B L E S H O O T I N G
Attempt to isolate trouble to one circuit through opera-
tional and visual checks. Verify that the apparent trouble
i s a c t u a l l y a m a l f u n c t i o n w i t h i n t h e T y p e 4 9 1 a n d n o t
improper controls setting or malfunctioning associated equip-
ment. Note the effect the controls have on the trouble symp-
toms. Normal and abnormal operation of each control helps
establish the location and nature of the trouble, Control
functions are described in the Operations section.
Check the instrument calibration or the calibration of the
affected circuit. The trouble may be corrected after calibra-
tion, The calibration procedure is given in Section 6. Before
changing any adjustment settings during this check, note the
position of the adjustment, so it can be returned to its original
position after the check. This will facilitate recalibration after
the trouble has been found and corrected.
Check circuit voltages and waveforms against those shown
in section 9 of the manual. Fig. 4-22 through 4-26 provide
board wiring drawings and component layout information.
It is usually best, if the trouble is not isolated to a circuit,
Fig. 4-21. Electrode configuration for socket-mounted transistors and
field effect transistors.
4 - 1 8
Содержание 491
Страница 4: ...i i Fig 1 1 The Type 491 Spectrum Analyzer ...
Страница 24: ...2 16 Fig 2 17 Control set up chart ...
Страница 34: ...Fig 3 1 Function block diagram of the Type 491 3 2 ...
Страница 42: ...Fig 3 10 Block diagram of the video detector and vertical amplifier 3 1 0 ...
Страница 48: ......
Страница 53: ...Fig 4 4 Power Supply Circuit board assembly with wiring color code 4 5 ...
Страница 54: ...Fig 4 5 Horizontal Display circuit board assembly showing color code to pin connectors 4 6 ...
Страница 55: ...Fig 4 6 IF Control board assembly Wiring color code to pin connector 4 7 ...
Страница 64: ...Fig 4 20A Tube subassembly removal procedure 4 16 ...
Страница 65: ...Fig 4 20B Tube subassembly installation procedure 4 17 ...
Страница 68: ...Fig 4 22 Power supply board assembly with component call out 4 2 0 ...
Страница 69: ...Fig 4 23 Vertical Amplifier and Blanking board assembly with component call out 4 21 ...
Страница 70: ...Fig 4 24 IF control board assembly with component call out 4 22 ...
Страница 71: ...Fig 4 24 IF control board assembly with component call out 4 23 ...
Страница 72: ...Fig 4 25 Horizontal display board with component call out 4 24 ...
Страница 73: ...Fig 4 25 Horizontal display board with component call out 4 25 ...
Страница 74: ...Fig 4 26 Phase lock board with component call out 4 26 ...
Страница 88: ......
Страница 90: ...Fig 6 1 Test equipment recommended for calibration of the Type 491 6 2 ...
Страница 91: ...Fig 6 2 Test equipment recommended to measure the dial accuracy receiver sensitivity and response flatness 6 3 ...
Страница 138: ......
Страница 191: ...APPENDIX A BASIC ISSUE ITEMS LIST Basic issue items list will be published at a later date A 1 ...
Страница 192: ......
Страница 195: ...SECTION II B 3 ...
Страница 196: ......
Страница 200: ......
Страница 201: ...SECTION 9 DIAGRAMS MECHANICAL PARTS LIST ILLUSTRATIONS ACCESSORIES ...
Страница 202: ......
Страница 203: ...9 1 ...
Страница 204: ...9 3 ...
Страница 205: ...9 5 ...
Страница 206: ...9 7 ...
Страница 207: ...9 9 ...
Страница 208: ...9 11 ...
Страница 209: ...9 13 ...
Страница 210: ...9 15 ...
Страница 211: ...9 17 ...
Страница 212: ...9 19 ...
Страница 213: ...9 21 ...
Страница 214: ...9 23 ...
Страница 215: ...9 25 ...
Страница 216: ...9 27 ...
Страница 217: ...FIG 1 9 29 ...
Страница 218: ...FIG 2 REAR 9 31 ...
Страница 219: ...9 33 FIG 3 IF CHASSIS PHASE LOCK ASSEMBLIES ...
Страница 220: ...FIG 4 POWER CHASSIS 9 35 ...
Страница 221: ...FIG 5 TIME DIV SWITCH OSCILLATOR ASSEMBLIES 9 37 ...
Страница 222: ...FIG 6 CRT SHIELD ASSEMBLY 9 39 ...
Страница 223: ...FIG 7 CABINET ASSEMBLY HANDLE 9 4 1 ...
Страница 224: ...FIG 8 491 STANDARD ACCESSORIES FIG 8 491 STANDARD ACCESSORIES 9 43 ...
Страница 225: ......
Страница 226: ...PIN 028017 000 ...