Executive Block Troubleshooting; Front Panel Block Troubleshooting - HP 5334B Service Manual

8-365. If the RATIO measurement is good, set the counter to FREQUENCY A, still using the 10 MHz
reference as an input. If the measurement varies more than
+
2 counts, the interpolator circuitry is defective.
a. Check the interpolator output of MRC U20 at pins 13 and 16. The interpolator pulses at these output
pins will be too small to measure, but the dc level should be between
+
2.0 volts and
+
2.3 volts.
b. Check the Interpolator outputs of the Multi-Function Counter (MFC) U14 at pins 1 1 and 17 with an
oscilloscope. The low frequency pulse streams should be visible with an amplitude of 100 mV riding
on a dc level of
+
4 volts.
8-366. EXECUTIVE BLOCK TROUBLESHOOTING
8-367. Failure Messages that can indicate problems in the Executive Block are referred to in Table 3-4, in the
Operating and Programming Manual. The two categories of failure are:
Failure of the Executive microcomputer (MCU)
Failures in communication between the MCUs
8-368. The first category deals with the the internal ROM and RAM of the Executive MCU which is checked
during power-up. The failure codes are 6.0 and 6.1.
8-369. The second category covers communication between MCUs. This is checked at power-up and con-
tinuously while the Counter is operating. The failure codes are 9.0,9.3, and 9.4.
8-370. If Failure Messages do not provide the cause of the problem, it is suggested that Signature Analysis be
used to troubleshoot the Executive Block. The instructions for using Signature Analysis to troubleshoot the
5334B are listed following the paragraph 8-456, SIGNATURE ANALYSIS.
8-371. FRONT PANEL BLOCK TROUBLESHOOTING
8-372. Should the Display and Keyboard Block fail, it is possible to use the power-on diagnostics to isolate the
problem. The power-on test lights all front panel LEDs. Refer to the Operational Verification Tests in Section
IV of the Operating and Programming Manual for more details.
8-373. The seven-segment displays can be replaced individually. These displays are checked by running through
the power-on test or by selecting the GATE TIME and entering a sequence of 8's on the display. If only one dis-
play is not working, replacing it should clear up the problem. If more than one display is faulty, the problem is
probably elsewhere in the block. If only the 8 left-most displays or the 2 right-most displays are faulty, the respec-
tive driver, U1 or U2, is probably bad. The seven-segment displays can be replaced through the front panel by
performing the removal and installation procedures in paragraph 8-291.
8-374. If the entire display is defective, another component sharing the Executive Data Bus may be at fault.
Remove the HP-IB microcomputer (MCU) U17 to see if the problem clears up. If not, replace the the Executive
MCU (U19). Should the problem still exist, drivers U1 and U2 are probably bad. After front panel disassembly
(refer to paragraph 8-287 for procedure to disassemble the front panel), the defective driver can be found by
switching U1 with U2. Only one driver at a time should be plugged back in, as the defective one may be shorting
the Executive Data Bus.
8-375. Note that there are two sets of codes which the 5334B may display. The first set of codes, called Error
Messa~es, indicate operator errors, either through incorrect keyboard entry or incorrect HP-IB programming.
The second set of codes, called Failure Messages, indicate internal hardware failures which may occur in a par-
ticular area of the Counter. A complete list of codes is provided in Tables 3-3 and 3-4 of the Operating and
Programming Manual.
HP 5334B
-
Service Manual
8-53