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Agilent 54845A Failing all trigger self tests

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MarkL:
There's a standard conversion for pinouts between ECL packages.  See attached.

The full app note is here (good reading if you're interested in ECL design):

  http://www.onsemi.com/pub/Collateral/TND309-D.PDF

TRN:
Mark,

Many Thanks :-+

rickells:
hi,

My Agilent 54845a has  Trigger self-test "Failed"  on all three of the Trigger tests;  for all 4 channels.
The scope does power On & can measure the Sq. wave signal from the Aux Out, & other signals Ok, (with knobs twiddled manually).
  It passes all of the other self-tests, .... just Not any of the 3 Trigger tests.

I have cleaned the ADC's, examined the Acq board for solder/IC placement issues, but see none.

Over the years there have been a few individuals who had the same issue (JayW, JWalling, TRN) & perhaps others, but details seem not to be found...

   TRN seems to have started to examine voltages & signals ...
       somewhat difficult with no schematics in the service manual.

1)  -- How was this Trigger problem fixed ??

thank you,
rick

Previous references to Agilent / HP 54845a & 54831b or 54832b Trigger problem:

https://www.eevblog.com/forum/repair/sometimes-knowing-what-something-means-is-half-the-battle-agilent-54831b-error/msg1008382/#msg1008382
https://www.eevblog.com/forum/testgear/agilent-54845a-failing-all-trigger-self-tests/
https://www.eevblog.com/forum/testgear/agilent-54835a-scope-(4-channel-1ghz-4gss)-repair-uphack/
https://www.eevblog.com/forum/repair/agilenthp-54845a/msg1267378/#msg1267378
https://www.eevblog.com/forum/testgear/agilent-54831d-modernising/


https://community.keysight.com/thread/6575
https://community.keysight.com/search.jspa?q=54845a
https://community.keysight.com/message/15068

http://www.dasarodesigns.com/projects/fixing-an-hp-agilent-54845a-infinium-oscilloscope/

https://wonghoi.humgar.com/Hobby.htm

Alfons:
If you're still interested: I've upgraded a 54815 to a 54825. After that, the device wanted a recalibration. All channels showed Trigger Fail. After a long search, I found this thread: https://www.eevblog.com/forum/testgear/_fdc-failure_-on-scope/ and the contribution of free-electron:


--- Quote from: free_electron on May 12, 2013, 07:35:58 pm ---i may have that laying around. i definitely have the ls drives. the machine has the adapter already in it. simply unplug the floppy and floppy cable. follow the floppy cable. it goes to one of the PCI boards. and from the pci board there is another to the motherboard. ( not the IDE ! , the floppy ) unplug both those cables. ( not the IDE on the pci card ! )
look again on the pci card. you'll see a the ide being translated to the fine pith ide of a laptop drive. unplug the large IDE cable and install an IDE cable with a split connector.

hmm. i realize it is hard to describe in words if you 've never done this. leme take a few pictures. i'm working on a 825 right now with a failed attenuator for a friend of mine. just replaced it running cal now. i'll snap a few pictures so you see how it is installed.

running self calibration is a bit tricky on these machines. the service software has some quircks.
you need to run probe cal first ( vertical menu ). disconnect everything. set attenuators manully to 1:1 on ther vertical menu. then run probe cal and follow the prompts. you need a short bnc ( less than half meter). the scope uses an internal 32 bit ( yes 32 bit ... ) dac to cal the input.

once that is done you can do the real cal. make sure to let the machine heat up for half an hour prior to doing that. you may get trigger failures otherwise.

the LS drives are matsushita or mitsubishi:

http://www.ebay.com/itm/HP-3-5in-359007-001-LS120-SuperDisk-Drive-MF357H-453MG-/370811752744?pt=US_Floppy_Zip_Jaz_Drives&hash=item56561a5128

thats the exact one with the right connector. there is others with different connectors but those don't work as they dont fit the adapter

--- End quote ---

The device ran for an hour before the test. And I also ran the ProbeCal for all channels before the calibration. That worked then. All channels could be calibrated without error.

But also before I had let the device warm up. I think that's actually a software bug in many cases when all channels report Trigger Fail.

ARF:
The same scope, the same problem.

As soon as I received it, I did a self test and the self test passed well.
After that I tried to do a calibration - but the calibration failed with an error on channel 3.
The next day I decided to repeat the calibration, but I received errors on all channels.

I did the self-test again and it already failed with 4 trigger errors.

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