Products > Test Equipment
HP/Agilent 1675x logic analyzer card memory up-hack
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texaspyro:

--- Quote from: MarkL on September 26, 2017, 03:14:46 pm ---
Good memory!  That seems to be the recipe!

I took one of my 16534A cards and swapped R809 and R810.  It became a 16533A.

Using a 0dB reference point at 10Mhz, the 16534A had a -3dB point at 623MHz (not bad - I hadn't measured this before).  When it became a 16533A the -3dB point was reduced to 346MHz.  So, even back then it seems HP was doing their artificial limits on BW.

Someone with a card manufactured as a real 16533A should double check this to make sure there's no other changes needed.


--- End quote ---

I originally found those resistors when, many years ago,  I bought a couple of expansion chassis that had 4 x 16533A's in them.  Last night I dug out a defective 16534A that I tried to back-grade to a 16533A to see if that made a difference (didn't) and spotted the swapped resistors.   I originally thought the resistors were by one of the PGA chips...  That was probably a different board I was remembering.
fisafisa:
Thanks.
I will try the modification.
DocBen:
Hi there,

I can confirm that a 16740a can be converted to a 16742a by removing one resistor. I used a picture of a 16742a.
I also tried to convert it to a 16752b but that failed, probably because I only have 1.5k resistors and I think the resistors create a voltage divider so I probably had the wrong voltages.
I will try again once I have some 1k resistors.
DocBen:
Yatta!

So I have finally gotten around to try to get a 16740a to be a 16752b.

On my third attempt I succeed. (keep in mind however this just passes the self tests. I havent made any actual measurements with it so it might fail when doing actual work)

from R735 to R82:  - -RR-RRR- 
does it. (- open, R well, you know)

I used 1K 0.1% Resistors just like they are used on the board
MarkL:
Wow, that's interesting!  Of the many possibilities for ID upping, I would have ranked the 16740A --> 16752B as having one of the least chances of actually working.

Does your 16740A have the same amount of memory populated as a 16752B?  The 16752A has 34 x Micron 48LC4M16A2-8E (4M x 16).
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