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Agilent 54835A scope (4 channel 1GHz / 4Gs/s) repair & uphack

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Tony_G:
Any update? Just wondering how it turned out.

Jwalling:

--- Quote from: nctnico on July 08, 2017, 12:45:09 pm ---
Back to the uphacking part. I located several resistors and decided to attach some switches after a few futile attempts to change the resistors using SMT tweezers.



The scope software can be stopped using ctrl-alt-del which opens up the task manager on Win98 and restarted from the menu so testing all the combinations could be done quickly.

--- Code: ---R3 R2 R1 R0
-  -  X  X  54835A
X  X  -  -  54845A

X = placed, - = open

--- End code ---

I have not found the 54846A mode but I have not included R4 in my test because I didn't spot it when looking for potential candidates. For now I'm fine with the 54845A mode.


--- End quote ---

According to the notes I have (and I think I PM'd them to you), there are only two resistors used for strapping. Was I incorrect?

(note that my crappy drawing doesn't show that R1 is also 0 Ohms.)

I have a 54846A on my bench that I'm repairing at the moment (bulging caps on the motherboard). When I get it up and running, I'll pull the ACQ board and verify the config.

When I had the motherboard pulled, I noticed that the date code on the sheet metal under the MB was dated 2001, yet the serial prefix is MY40. How can this be? :-//  I would have thought that the sheet metal should have been older, or the serial # newer...



Jwalling:
Here's the 54846A. Just two resistors need to be de-populated, so my drawing is at least correct for the 54846A.

nctnico:
I must say I tested my scope with software version 3.x so maybe that version doesn't support the 54846A  :-// But it is good to know which strapping I need alter in order to unleash more bandwidth  >:D

Jwalling:

--- Quote from: nctnico on November 02, 2017, 05:02:52 pm ---I must say I tested my scope with software version 3.x so maybe that version doesn't support the 54846A  :-// But it is good to know which strapping I need alter in order to unleash more bandwidth  >:D

--- End quote ---

I'm not sure about that one...

Now that I'm playing with one of these again, I remember one thing I really dislike about them. They won't trigger for shit at anywhere near their rated bandwidth with a sine wave applied. This one craps out at about 1.3GHz, and I'm combining CH1 CH2 for 8GS/s. There was an excuse explanation by an Agilent Keysight support engineer (I think it was Algoss) that I bookmarked, but I guess the link didn't survive a change in their forum. Or maybe they trash the old stuff.
It was here: http://www.keysight.com/owc_discussions/thread.jspa?messageID=118580&#118580

Should have saved it locally :rant:

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