Analog-Digital Converter, Troubleshooting
The
Analog Digital Converter converts the analog video and sweep voltages to digital
data. Consequently, a failure on this assembly will affect the display of trace A and trace B
data. Character and graticule generation are not affected by
Stuck bits in the Ramp Converter will distort the displayed signal. This is most easily
observed with slow sweep times. When a bit fails, the Ramp Converter will default to a 20 ms
sweep rate during the display period when that bit would normally be working. Figure 1-3 is
an example of the CAL OUTPUT signal with a 3 s sweep time when U5 pin 5 is struck low.
0 . 0
C E N T E R
S P A N
3 . 0 0
Note
I
Center Frequency Readout will be 20.000 000 MHz for an
HP
8567A
Figure 3. Ramp Converter Bit Failure
By looking at noise with a 3 s sweep time (push Instrument Preset first), it is possible to
determine which of the data bits are stuck by counting the discrete states displayed. For
example, Figure 4 shows the result of an MSB failure
= 2 states are displayed.
To detect low order bit (DO-D4) failures, tune to the CAL OUTPUT signal and set frequency
span to 100
sweep time to 3 s. A failure will then result in slight “stair-stepping” of the
displayed signal. The noise display will be missing states, but this will be difficult to see.
Digital Storage Test Program 4 is used to verify the inputs to the DAC, U5.
is close to
the low end of its tolerance,
of DAC U5 may not be properly set.
Failures in the video analog to digital process are characterized by “stair-stepped” signals and
noise that is displayed as discrete vertical lines. Low order bit failures will cause many small
steps while a high order bit failure will cause a single step that will eliminate the peak of the
display. Note that only the signal will be affected and that the graticules and characters will
not be affected. Front panel displays of the CAL OUTPUT signal for several bit failures are
shown in Figures 5 and 6.
3
Содержание 85662A
Страница 13: ......
Страница 14: ......
Страница 17: ...can cause the CRT to be disabled If U14 is operating correctly visually inspect the A4A9 assembly Al 3 ...
Страница 18: ......
Страница 27: ......
Страница 28: ...AlA KEYBOARD Al Front Panel Assembly and Component Locations ...
Страница 30: ......
Страница 49: ......
Страница 51: ...3 AlA XYZ Driver Amplifier Component Locations 85662 60236 ...
Страница 52: ......
Страница 53: ......
Страница 54: ......
Страница 72: ......
Страница 73: ......
Страница 77: ......
Страница 78: ......
Страница 84: ......
Страница 92: ...V I E W A AlA lII1 0 O0 4 JII fi V I E W B Figure 1 IF Display Section internal Fuse Replacement 8 Al A6 Al A7 ...
Страница 108: ......
Страница 109: ......
Страница 111: ...I 1 AlA f15 V Regulator Component Locations 85662 60232 85662 60250 ...
Страница 113: ......
Страница 114: ......
Страница 115: ......
Страница 122: ......
Страница 124: ...DSl M A I N S I N D I C A T O R C6 CATHODE 4 1 El r l CR9 P I AlA Rectifier Component Locations 85662 60204 ...
Страница 125: ...c 4 C 6 R 6 I 0 C R 9 0 CR10 AlA Rectifier Component Locations 85662 60234 ...
Страница 126: ...0 El E2 r r L J L J _ I 0 0 0 0 AlA Bus Transition Component Locations 85662 60056 ...
Страница 127: ......
Страница 128: ......
Страница 129: ......
Страница 131: ......
Страница 133: ......
Страница 142: ......
Страница 161: ......
Страница 163: ......
Страница 178: ......
Страница 179: ... R51 Y S H BAL R50 X S H BAL R12 LL THRESH A3A2 Intensity Control Component Locations 85662 60025 85662 60245 ...
Страница 180: ......
Страница 181: ......
Страница 195: ......
Страница 196: ...R 8 YSL L Il ln R IC7n XSL 0 0 0 R 5 I I Y G A I N R 2 Y E X P A3A3 Line Generator Component Locations 85662 60128 ...
Страница 198: ......
Страница 203: ......
Страница 205: ......
Страница 210: ......
Страница 212: ......
Страница 216: ...Verify binary count sequence starting at the least significant bit SO 500 ns square wave to S7 64 ps square wave 4 A3A6 ...
Страница 219: ......
Страница 221: ......
Страница 226: ......
Страница 228: ......
Страница 241: ......
Страница 256: ......
Страница 258: ...R 5 7 T H G A I N R59 T H O F S A3A9 Track and Hold Component Locations 85662 60165 ...
Страница 259: ......
Страница 260: ......
Страница 262: ...ASXAlPI I A3XA2P 1 AJXAJP 1 A3XA4P 1 A3XA5P 1 A3XA6Pl A3XA7P 1 A3XA9P 1 AJXAlP2 A3XA2P2 A3XASP2 A3XA6P2 A3XA7P2 ...
Страница 263: ......
Страница 266: ......
Страница 274: ......
Страница 275: ...R2 LG OS p 10 C6 I I R14 ar OS 1 5 1 A4Al Video Processor Component Locations 85662 60122 ...
Страница 276: ......
Страница 293: ......
Страница 294: ...2 k 4 5 7 J2 F1 TEN R91 12VTV R14 LG 20 A4A2 Log Amplifier Detector Component Locations 85662 60132 ...
Страница 295: ...2 4 5 1 0 N a R79 ZERO 4 E N TV R14 LG 20 A4A2 Log Amplifier Detector Component Locations 85662 60166 ...
Страница 296: ......
Страница 297: ......
Страница 315: ......
Страница 316: ...10 A 1 2V T Y P 7 V T Y P A4A3 Log Amplifier Filter Component Locations 85662 60009 ...
Страница 318: ......
Страница 319: ......
Страница 321: ... 15v t15v cl7 ETC Figure 2 A4A4 Input Buffer Amplifier Current Sinks 2 A4A4 ...
Страница 334: ......
Страница 336: ...c 4 3 L C D I P c41 L C D I P A4A4 Bandwidth Filter Component Locations 85662 60189 TR ...
Страница 337: ......
Страница 338: ......
Страница 352: ......
Страница 354: ......
Страница 363: ......
Страница 365: ...A4A8A2 Down Converter Component Locations 85662 60005 ...
Страница 366: ...c31 R29 1 8 4 M H z NULL W I D E G A I N A4A6Al Up Converter Component Locations 85662 60006 ...
Страница 367: ......
Страница 379: ...c40 c 4 1 PK SYM y Hz A M P L 10 Hz AMPL A4A7 3 MHz Bandwidth Filter Component Locations 85662 60004 85662 60174 ...
Страница 380: ......
Страница 399: ......
Страница 402: ......
Страница 403: ......
Страница 409: ...Table 4 Video Bandwidth Truth Table 6 A4A9 ...
Страница 428: ......
Страница 429: ......
Страница 430: ......
Страница 434: ......
Страница 447: ......
Страница 452: ...A4A6A2 Output Driver Component Locations 85662 60170 Option 067 Tab ...
Страница 453: ...A4A6Al Input Buffer Component Locations 85662 60171 Option 067 Tab ...
Страница 454: ......
Страница 470: ......
Страница 473: ...Table 4 Video Bandwidth Truth Table Option H96 3 ...
Страница 498: ......
Страница 504: ...Table 4 Video Bandwidth Truth Table 100 Hz H 30 Hz H H 10 Hz H 3 Hz H 1 Hz 6 Option 462 ...
Страница 514: ......
Страница 523: ......
Страница 531: ......
Страница 548: ......
Страница 549: ......
Страница 550: ......
Страница 582: ...This page intentionally left blank 32 General Parts Listing ...
Страница 594: ...HEWLETT PACKARD HP Part No 85662 90085 Printed in USA ...