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Re: HP 83592B hangs 8350B sweeper
¿ªÔÆÌåÓýHi Peter, I have done this calibration several ?time , I think ?the A vs B is the X-Y display on the scope , I was using the HP 1740A oscilloscope to do this. The intensity must set to the high position because it is difficult to see the crest of the ramp to 0V. Regards ON1EV Belgium De?: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] ? ? Has anyone done a calibration on one of these plug-ins? Step 20 in adjustments: What does A vs B mode on an oscilloscope mean? I think HP means trigger on B and look at A ??(A + B or A ¨C B will not work. The waveforms are completely different time/div and shapes) A6-TP8 does not have positive sweeps as shown. They go negative from 0 to -10v. Step 22: A6R37 will not affect TP8 an far as I can see. Am I missing something? ? From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]
Sent: October-17-15 5:54 PM To: hp_agilent_equipment@... Subject: RE: [hp_agilent_equipment] HP 83592B hangs 8350B sweeper ? ? GREAT PROGRESS! Thanks Steve, you are quite correct. My A7 board is marked 83595 and works in this 83592 plug-in. However I suspected that the A6 board that was causing all the trouble was actually from an 83595 not an 83592. I removed the 4L and 4H pots, installed the R63 pot, moved the Band jumper, ?and concentrated on the Sweep Control and Bandswitch circuits. The A3 SW1 forces the signals to go through the variable gain amplifier for troubleshooting. Using this setting I could sweep band 0 but was finding that the TP7 signal was going positive by 2.4 volts. It should start at 0v and go negative to -10v max. There was an offset in the variable gain amplifier! I had also noticed that the gain seemed high. The schematics showed the gain resistors to be the same as the ones on the bad A6 board but they were different from the ones on the good A6 board. The parts list agreed with the resistors on the good A6 board so I assumed them to be correct. This was not the first error on the schematics I had found. Troubleshooting: Set sweep from 1 MHz to 1.1 MHz so TP5 is essentially at 0v. Check TP1 (BandSw DAC O/P) is 1.195v on good A6 and 1.194 on bad A6. So far so good. Check U5-6 is -10.05v on good A6 but is? -12.73v on bad board. TP7 is 0v on the good A6 but is +2.4v on the bad board. Conclusion: the gain is too high and is tripping U14 in the Bandswitch Comparator. Change all 4 gain resistors: R29???????? B0?????????? was 109.73k??????? change to 82.541k (TP7 is now 0v with the above test) R27???????? B1?????????? was 57.014k??????? change to 42.884k R25???????? B2?????????? was 40.423k??????? change to 30.423k R23???????? B3????????? was 40.423k??????? change to 30.423k Now the plug-in sweeps from 0.01 to 20 GHz and the INSTR PRESET no longer hangs the 8350B. Conclusion: The A6 board was from an HP 83595. I can now proceed with the calibration bu expect some problems because the resistors I used were 1%, not 0.1%, and are not the exact values. I may not have enough range of adjustment. I may also run into problems in the SRD and PIN diode bias circuits because of component values. Some of the analog switches are normally closed (PMI SW06) but are shown open on the schematic. U2A pins 1 & 2 are switched, U2A-2 goes to U13-11. Peter. ? ? From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] ? ? Peter, ? I have an 83594A and an 83595A wth boards that have mismatched part numbers so it may not have been anything nefarious but if so its contagious! There are a couple of boards that don't match any of the manuals I've been able to find, and there are switches that open parts of loops, and pots for adjustments, and none are mentioned in any manual. The "joys" of working on older gear! WB0DBS ? ?
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