Electronics > Repair
Series defect on agilent 167xx boards?
<< < (35/50) > >>
MarkL:

--- Quote from: ahakman on March 25, 2023, 06:40:43 am ---...
The one failing the ZoomAcq test seemed very suspiciously similar to the failing PLL chip problem reported earlier in this thread, so I just swapped the PLLs on the 2 boards that had problems, and now I have one card that works entirely, and presumably one that's failing both memory unloads and the ZoomAcq tests now.

Does anyone still have any "beyond repair" cards they could scavenge a PLL chip from? Or that maybe are not quite as "beyond repair" as they thought?

--- End quote ---
Wow, another dead PLL.  Can you see any clock output from the dead one?

The PLL can be had on any of the 167xx cards with Timing Zoom except the 16715A.  It might help to know your country for anyone who can scrounge up a PLL.


--- Quote ---Does anyone have experience with where the fault would be for the Memory Unload Modes Test? Reading the service manual, that test tests reading the memory data off the card to the backplane (so presumably to the CPLD chips close to the backplane connector). The card that's failing that test had by far the worst corrosion on it. I suspect one of the vias around the middle runner (with the huge parallel bus of tracks that runs up the middle of the card), or the next 2 runners towards the "POD 1/2" side of the card - there was some very nasty corrosion there, but I just can't see anything that looks broken after I cleaned it all up. I tried probing a few of the most suspect vias on a known good card to see if I could find where they went, so I could test which one was broken on the broken card, but I wasn't able to trace some of them (inner layer traces to BGA pads I'm thinking??)

--- End quote ---
It's really better to check continuity via to via on all the traces running through or near corroded areas.  Extremely sharp probes pushed into the via holes at an angle works well.  On multiple occasions I've had traces with no visible breaks and it turned out the corrosion had gotten under the soldermask.  It can take some time to do the testing.  But you're right, it could also have eaten away the via hole plating, and that's happened to me too.

The HP-UX based analyzers are able to turn on detailed debugging output when running any of the verification tests (pv).  Is there any more detail from the windows version on which bit(s) and/or chips are failing during "Memory Unload Modes Test"?

On the 1675x cards I think the acquisition memory access path from the backplane is through one of the FPGAs near the backplane connector (I think it's the Altera MAX), up to the Virtex FPGAs on top, and then back down to the actual DRAM chips.  On the 1671x cards, it goes direct from the backplane controller FPGA to the memory chips (there are no Virtex FPGAs acting as a memory controller layer).
dorkshoei:

--- Quote from: MarkL on March 25, 2023, 07:33:34 pm ---Just to be clear, is the 16534A that's failing its cal passing all the self-tests?  If you run it anyway, can you see any traces with a signal applied to one or both channels?

--- End quote ---
The card had been working (at least for my usage) the previous time I tried.  Now it passes self-test but fails most of the cal.  I'd have to try again to see if it's still showing traces.


--- Quote ---I've never worked through the performance section.  It seems like it's a fair amount of work and wouldn't gain you that much unless you were using the card to produce verifiable test results.

--- End quote ---
I'm not.  I just don't want to glue down the new runners only to find there is a fault :-)
MarkL:
One further thought on the failing 16534A scope card...

It's worth the time to check the on-board regulator outputs before heading down other troubleshooting rabbit holes.  There are five regulators and their output voltages are all labeled on the top of the board.

I had one card that self-tested fine, but consistently failed calibration because one of the output setting resistors had gone bad.

I've also had bad output setting resistors on logic analysis cards too, so it's never a bad idea to verify regulator outputs on these cards also.  I remember one card that had a very out of spec ECL termination voltage, which caused a number of self-tests to fail.

Bad resistors occur more often on cards that have corrosion.  Maybe the corrosion is getting into the film on the resistor, but I've never been able to see any damage under a microscope.  It's a just a correlation at the moment.
MarkL:

--- Quote from: dorkshoei on March 25, 2023, 08:35:44 pm ---...  I just don't want to glue down the new runners only to find there is a fault :-)

--- End quote ---
Understood.  I left my runners off, and I dislike conformal coatings passionately.  Time will tell if I'm wrong.
MarkL:
On the 16534A card again...

Besides the previous question on the self-test, are the cal errors associated with one channel or both?

If faulty on only one channel, a useful troubleshooting technique is to compare signals on equivalent nodes between the working and broken channel.

Similarly, if you have a fully working card, you can use that as your comparison.  A working card is a really useful resource, given the lack of any detailed documentation for these units.

You can probe two cards at the same time by using a 16701B expansion chassis, or a home-made card extender.  User DogP has some gerbers available for an extender that works well:

  https://www.eevblog.com/forum/repair/series-defect-on-agilent-167xx-boards/msg4031926/#msg4031926

There was another user who had done something similar (or was working on it), and I think it was a full-length extender card.  Can't find the post at the moment.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod