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HP/Agilent 1675x logic analyzer card memory up-hack

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MarkL:
In the course of repairing some 1675x cards, I discovered that HP/Agilent is using resistors to set the model ID, and hence the capture memory size on these old logic analyzer cards.  The main clues were:

- All models already have the full complement of memory for their series,
- There was sloppy soldering work (solder splatter, flux residue) on unpopulated resistor pads that were in an obvious grouping (indicating that some had been removed after manufacture),
- The only indication of the model number was a solitary adhesive sticker,
- And finally, HP/Agilent is known to use ID resistors in other products.

I haven't seen this info anywhere else, so I'm posting here.

I've verified the following ID conversions work (with full memory testing):

  16751A --> 16752A
  16754A --> 16756A
  16755A --> 16756A

Specs and other details for the cards discussed in this post:

  http://literature.cdn.keysight.com/litweb/pdf/5968-9661E.pdf

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Series: 16750A, 16751A, 16752A
Memory: 34 x Micron 48LC4M16A2-8E
Max model: 16752A with 32MSa

There are nine ID resistor footprints arranged in a column: R735, R65, R66, R68(?), R63, R73, unlabeled, R78, and R82.  They are near the pair of Altera LQFP's near the backplane connector.  (It's possible R735 does something else besides ID, but it's unpopulated and near the others so I'm including it.)  To make a 16752A, all the resistors are populated except R735, R66, R63, and R82.  Resistors are 1k 0805.



There are also "B" versions of each of these cards.  The (bad) photos I can find look like they have the same layout, so I would expect it to work with them also with possibly different resistor labels or combinations (maybe one controls the A vs. B?).

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Series: 16753A, 16754A, 16755A, 16756A
Memory: 18 x Micron 46V16M16-75
Max model: 16756A with 64Msa

There are eight ID resistor footprints arranged in a matrix: two rows A and B, and four columns 1, 2, 3, and 4.  They are near the Xilinx FPGA U128, which is near the backplane connector.   To make a 16756A, all resistors are populated except B3 and B4.  Resistors are 1k 0805.



There's also an EEPROM on this card, but it doesn't seem to have anything to do with ID.  It's probably only used for calibration data.

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Other Cards (which I don't have so I can't try it)

The 16740A, 16741A, and 16742A from photos look very similar (perhaps identical?) to the 16750A/51A/52A series and with ID resistors in the same PCB area.  Hopefully a 1674x owner can figure this one out since it might need different resistor positions populated.  Please post your results if you try it.

I'll also note that the 1674x and 1675x series cards are identical spec-wise except for memory configurations, occurrence counters, and maximum state speed.  So, I suppose it's possible that a 1674x could be turned into a 1675x by using only ID resistors, but it would require a closer look at the memory configuration on the board and subsequent testing at higher speeds.  Again, something for a 1674x owner to try.


It may also be possible to turn a 16718A (8Msa) into a 16719A (32MSa), but I can't find enough photos to know if the board layouts and memory configuration are the same.  The 16719A at least has a similar board layout to the 16740A/41A/42A and 16750A/51A/52A series, so it probably has ID resistors.


Somewhat related to this topic, I've also heard of a hack to turn a 16533A 250MHz 1Gsa/sec scope card into a 16534A 500MHz 2Gsa/sec scope card via a resistor ID.  If anyone knows the specifics, please feel free to share.  Or if you have a 16533A, post a high-res photo (front and back) and I can probably figure it out from there.

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Good luck if you try any of this, and please post your results here if you do!

gslick:
Interesting information. This is the first time I have seen this. Thanks for sharing.

I'll have to check what types of modules I have. I think have all three of 16750, 16751, and 16752, and at least either a 16718 or 16719, or maybe both. Is the 16717 populated with a different memory configuration? Maybe only a 16741 from that line.

I've never bothered doing a careful examination of differences between the modules myself.

(I also have some of the 16753 - 16756 line that I have never used as I don't have any use for the 90-pin POD connectors).

MarkL:

--- Quote from: gslick on September 22, 2017, 02:50:18 am ---Interesting information. This is the first time I have seen this. Thanks for sharing.

--- End quote ---
No problem; hope it's of some use.


--- Quote ---I'll have to check what types of modules I have. I think have all three of 16750, 16751, and 16752, and at least either a 16718 or 16719, or maybe both. Is the 16717 populated with a different memory configuration? Maybe only a 16741 from that line.

--- End quote ---
I have a 16717 and it's significantly different than the others.  It has 34 x OKI M5416283 (256k x 16).  That comes out to 2Msa (34 * 256k*16 / 68channels), which is the 16717 spec, so there's no additional memory to be enabled.  Same with the 16715.

I'm also noticing there's the 16710A (8k), 16711A (32k), and 16712A (128k) which I missed on the datasheet before.  They also have the same specs except memory, so they may be a candidate too.

There may also be opportunities for cards in the 16500 series, but I have zero experience with them.  I think 16900 series card options are software controlled.


--- Quote ---(I also have some of the 16753 - 16756 line that I have never used as I don't have any use for the 90-pin POD connectors).

--- End quote ---
The 90-pin flying lead probe kits are outrageously expensive, which kind-of kills the attractiveness of those cards compared to the others.  I'm looking at building some single-ended probe breakouts (some day) out of E5378A adapters.  They're pretty cheap on ebay (~ $20), but I'll never get the kind of fidelity needed for the speeds of those cards.

MarkL:

--- Quote from: gslick on September 22, 2017, 02:50:18 am ---I've never bothered doing a careful examination of differences between the modules myself.

--- End quote ---
I don't think it would have occurred to me either.  What tipped me off was reading the service manual for the 16755A I was repairing at the time.  The manual covers all four 16753A/54A/55A/56A cards and talked about the use of 256Mbit DDR SRAMs for the acquisition memory.  My lesser card would presumably not need all the memory installed, yet, it didn't have any unpopulated memory footprints.  Hmmm...  Why is that?

texaspyro:
You can also upgrade a 16533A scope board to a 16534A board with a resistor mod.  Sorry, I can't find my notes on which resistors to change and no longer have a 16533A to compare to a 16534A. I seem to remember all the needed resistors were on the back.

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