Products > Test Equipment
Keysight 34465A reliability
tooki:
--- Quote from: AVGresponding on April 25, 2022, 10:43:11 am ---
--- Quote from: tooki on April 24, 2022, 10:44:17 pm ---Absolutely not.
A mod board is a patch made applied after the fact to an existing part to correct an error discovered after manufacturing, so that you don’t have to trash the existing part. They DID redo the existing part, and this board was designed to be there from the beginning of this redesign.
--- End quote ---
You don't think it's an error to design a board that needs to be changed to move some parts to a daughter-board? There is a design error here, whether in the original that required a revision, or in the revision that could not be made to work without the extra expense.
--- End quote ---
A mod board is a board bodged onto the ORIGINAL board, not to the new version! That’s the difference. If they’re designed to go together — as the new version and its daughterboard are — then it’s not a mod board!!
Again, to spell this out for you since you’re either not getting it, or are being deliberately obtuse: a mod is something designed AFTER a given version is manufactured, to be bodged onto already-manufactured boards. A mod board is, by definition, one for which the board it’s being attached to was not designed to accept.
Of course the original design had an error, that’s why they had to design a new board. But since the daughterboard was part of the new board design, and not an after-the-fact modification to the new board design, it’s not a mod board.
--- Quote from: AVGresponding on April 25, 2022, 10:43:11 am ---
--- Quote from: tooki on April 24, 2022, 10:44:17 pm ---Since we don’t know for sure why those parts were moved off the main board, we certainly can’t conclude that it’s because of making it a universal design. (I frankly doubt that it has to do with reusing the board in multiple models: it’d almost certainly be cheaper to make different boards than to have the added labor to solder on a daughterboard. Remember that that’s just one person’s random guess, not even the result of circuit analysis.)
Also, by what logic is a new board design not a board re-spin? :-DD
--- End quote ---
Because it is not a new board intended only for the 34465, it is intended (by fairly obvious implication) to be used at least in the entire 3446X family, and as some have speculated in the 34470 as well.
--- End quote ---
We don’t have any evidence for or against this claim. It could be right, but it could be wrong. So you shouldn’t treat it as gospel at this stage.
--- Quote from: AVGresponding on April 25, 2022, 10:43:11 am ---You also make an unwarranted assumption; that if the flux residue could be harmful, they would remove it. I explained in my last post why this is not necessarily so, and I can assure you I have the relevant experience to make the guesses that I did as to why they did not clean up afterwards.[/color][/size][/b]
--- End quote ---
Your explanation was so difficult to parse that it’s hard to understand exactly what you were saying.
But I stand by my claim that if it were harmful they’d remove it: if it harmed performance, then the performance would be suffering, and it’s not. And since they planned to leave it in place, they wouldn’t use a flux type that causes corrosion if left in place.
nctnico:
--- Quote from: tooki on April 25, 2022, 11:03:21 am ---
--- Quote from: AVGresponding on April 25, 2022, 10:43:11 am ---
--- Quote from: tooki on April 24, 2022, 10:44:17 pm ---Absolutely not.
A mod board is a patch made applied after the fact to an existing part to correct an error discovered after manufacturing, so that you don’t have to trash the existing part. They DID redo the existing part, and this board was designed to be there from the beginning of this redesign.
--- End quote ---
You don't think it's an error to design a board that needs to be changed to move some parts to a daughter-board? There is a design error here, whether in the original that required a revision, or in the revision that could not be made to work without the extra expense.
--- End quote ---
A mod board is a board bodged onto the ORIGINAL board, not to the new version! That’s the difference. If they’re designed to go together — as the new version and its daughterboard are — then it’s not a mod board!!
Again, to spell this out for you since you’re either not getting it, or are being deliberately obtuse: a mod is something designed AFTER a given version is manufactured, to be bodged onto already-manufactured boards. A mod board is, by definition, one for which the board it’s being attached to was not designed to accept.
--- End quote ---
I think you are both right/wrong. As Kleinstein already noted: Keysight did change the board layout but for some reason choose not to redo the entire layout but use an extra board instead. Likely Keysight didn't want to re-qualify / re-test a new board layout given the high performance they want to get out of the design.
tszaboo:
I had 1 out of 4 fail with random reboots, in the last 4-ish years. We sent it back they replaced it without question.
I didn't put too much though into it back then.
HighVoltage:
--- Quote from: Kleinstein on April 25, 2022, 07:52:54 am ---
A reason for the new board could have been the problem they had with the high voltage rating, though the rumors were that this was from the relay ratings.
--- End quote ---
The high voltage rating debacle later turned out to be not a problem at all.
So, I think it is very unlikely that this was the reason.
salvagedcircuitry:
--- Quote from: nctnico on April 07, 2022, 11:58:10 pm ---
--- Quote from: floobydust on April 06, 2022, 05:55:15 pm ---Likely not related to OP's fault, but something to point out (and I do hope I'm wrong here):
TI/Stellaris LM3S1D21 ARM processor is discontinued 2016 and withdrawn from the market due to the flash corruption issues. The parts are a lemon, known about in 2014.
"Flash corruption or device failure may occur at power on"
"Flash memory endurance cycle specification is 100 cycles"
"Flash memory corruption may occur when device is unpowered and stored for several months - Due to the storage oxide thickness and trap-assisted electron tunneling, there are more leaked cell values than originally expected in the Flash design within several months after programming. As a result, the ECC logic is not able to repair all of the errors in the Flash memory. Data derived from customer returns predicts that devices that are left unpowered at room temperature storage for 6 months can result in failure rates of 2000-3000 DPPM per year."
Ref: TEMPEST/INFERNO LM3S Errata Document (Literature Number: SPMZ861)
Bench multimeter product line 34461A, 34465A, 34470A use this MCU not as the main front panel processor but I think it's the Inguard processor.
If this is a real problem, silicon revisions need to be confirmed it's all 130nm parts, Keysight should be offering free extended warranty. It would be a massive debacle.
--- End quote ---
I'm afraid you are not wrong. It is a good find though so I appreciate you taking the trouble for digging this up. There is nothing to be found on TI's website about these microcontrollers nowadays. As if they never existed!
My 34461A also has the LM3S1D21 microcontroller revision A2 which is affected by the flash corruption problem. A way around it, is to leave the device on for at least 24 hours to give the internal flash controller the chance to fix the bits that have gotten corrupted. However, that system isn't failsafe as well and can actually corrupt data which was good. On top of that it is hard to tell whether a corrupted flash is signalled at all and how this affects measurements. It could be that the software continuous on with bad data affecting the measurement results.
All in all these units have a ticking time bomb inside them. :palm:
--- End quote ---
I just picked up a 34465a on the cheap and noticed that mine has a LM3S1D21 as well. How can I tell the revision of my LM3S1D21?
From the ti doc, it looks like my chip was produced September of 2015.
My unit has 2.14 firmware on it, but I have a feeling there is no firmware to fix internal MCU chip nand corruption :/
Thanks!
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