Keysight 34465A reliability

[Smith]

Glad you caught it before another transformer died!

I'd expect a primary side fuse that blows if the instrument is using 10x more current than expected. Is there none, or is it slower than the thermal fuse at this current level?

There is a primary fuse, not exactly sure what is is rated at. I guess it just overheated until the thermal fuse went out. Probably for multiple months, until it died entirely.

About the solder flux residue. I don't have a big problem with it unless it is at a high speed path, of a low level measurement path. This tends to give problems in the long run, particularly with higher levels of moisture in the air.

I see lots of flux residues in higher end measurement devices, especially with user selected options from the factory, big input/output connectors, and bodges. Actually, it f you cant see it, its not potentially dangerous for you or the device, is it really a problem?

[Kleinstein]

For the flux residue it depends on the type of flux. Some flux is corrosive and must be removed. Other flux is OK even in higher humidity conditions and works as a reasonable protection and may be preferred over a "clean" surface.  With some parts fited (e.g. switches, cables, relays) is may be very hard to get a good clean. A poor attempt on cleaning, so that the flux is no longer visible can do more harm than good.

The main reason for the primary fuse is to prevent a fire in case the transformer fails, not to protect the transformer from overload. It would be nice to have also some protection for the transformer, but this is tricky with quite some tolerances in the fuse tripping points and possible inrush current spikes.

[tooki]

Yes, I understand; it's more practical to create a mod-board than to re-spin the main one, usually.

Do you understand, though?? This isn't a mod board as such. A mod board is commonly understood to mean a daughtercard made to implement a bodge to correct an error on the main PCB, rather than making a new main PCB.

As I explained above, early versions of the board had this part of the circuit on the main PCB. Then on this later version, the main board was respun to move that part of the circuit onto a daughtercard.

This isn't a cost-saving measure, as it's more expensive in every way: the added engineering cost, a respun main PCB, a new daughtercard, and the extra labor to solder the daughtercard onto the main PCB.

[tooki]

I know, but that still doesn't make it ok

As wraper said, cleaning in situ could get flux residue into places it shouldn't be. And with the two boards soldered together, cleaning becomes much more difficult.

So you'd be adding a cleaning step with no advantage, but plenty of risk.

I guess you don't open many devices. If you did, you'd have noticed the flux residue found in all sorts of equipment, from consumer electronics to IT to test gear to appliances.

[Kleinstein]

The part in the red rectangle looks a lot like part of the overvoltae protection. A good guess on the parts are 2 back to back depletion mode MOSFETs and that 2 units in series. This can be used as sereis element in the input protection, though is may fail over time from high energy ESD or similar events with very high voltage (e.g. > 2000 V). A separate board could ease repairs and maybe give the option to offer different versions with even better protection or meeting other regulatory limits (e.g. military not comftable with FETs used for protection). So having this somewhat vulnerable part on a seprate daughterboard is a very reasonable thing.

The KS meters did have some problems with the maximum votlage specs and this extra board could be reaction to this, though the rumors were more pointing to the relay voltage rating as the cause.

[skander36]

It is very possible that this section to be involved in overvoltage protection. I don't understand what is the role of J110 jumper.
I want to ask the owners of the KS34465A  what is happened when touch the red wire when the DMM is on DCV mode. A relay is clicking every time when I touch the red wire when is on DCV. None of my DMM (nor Keythely nor Siglent) behave like this.

[AVGresponding]

Yes, I understand; it's more practical to create a mod-board than to re-spin the main one, usually.

Do you understand, though?? This isn't a mod board as such. A mod board is commonly understood to mean a daughtercard made to implement a bodge to correct an error on the main PCB, rather than making a new main PCB.

As I explained above, early versions of the board had this part of the circuit on the main PCB. Then on this later version, the main board was respun to move that part of the circuit onto a daughtercard.

This isn't a cost-saving measure, as it's more expensive in every way: the added engineering cost, a respun main PCB, a new daughtercard, and the extra labor to solder the daughtercard onto the main PCB.

Even by your own definition, it clearly is a mod board, as the new main board is (what appears to be) not a respin but a new "universal" design, intended to be used in multiple models, but which lacks the onboard capability for these necessary components in a 34465.

I know, but that still doesn't make it ok

As wraper said, cleaning in situ could get flux residue into places it shouldn't be. And with the two boards soldered together, cleaning becomes much more difficult.

So you'd be adding a cleaning step with no advantage, but plenty of risk.

I guess you don't open many devices. If you did, you'd have noticed the flux residue found in all sorts of equipment, from consumer electronics to IT to test gear to appliances.

Please leave ad hominem attacks where they belong; on the editing room floor (inside your head).

Difficult is not impossible, and the risk is a balance between existing potential for harm, post-cleaning potential for harm, and the additional costs of either having unwanted warranty claims (something we can only speculate about as Keysight will certainly not release such commercially sensitive information), or additional costs of cleaning plus potential unwanted warranty cost as a result of more harm being done than good.

Yes, I understand very well, thankyou, nevertheless it's cosmetically unattractive, and in an instrument where I expect seriously anal levels of cleanliness, it does not sit well.

[tooki]

Yes, I understand; it's more practical to create a mod-board than to re-spin the main one, usually.

Do you understand, though?? This isn't a mod board as such. A mod board is commonly understood to mean a daughtercard made to implement a bodge to correct an error on the main PCB, rather than making a new main PCB.

As I explained above, early versions of the board had this part of the circuit on the main PCB. Then on this later version, the main board was respun to move that part of the circuit onto a daughtercard.

This isn't a cost-saving measure, as it's more expensive in every way: the added engineering cost, a respun main PCB, a new daughtercard, and the extra labor to solder the daughtercard onto the main PCB.

Even by your own definition, it clearly is a mod board

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.

as the new main board is (what appears to be) not a respin but a new "universal" design, intended to be used in multiple models, but which lacks the onboard capability for these necessary components in a 34465.[/color][/size][/b]

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? 

I know, but that still doesn't make it ok

As wraper said, cleaning in situ could get flux residue into places it shouldn't be. And with the two boards soldered together, cleaning becomes much more difficult.

So you'd be adding a cleaning step with no advantage, but plenty of risk.

I guess you don't open many devices. If you did, you'd have noticed the flux residue found in all sorts of equipment, from consumer electronics to IT to test gear to appliances.

Please leave ad hominem attacks where they belong; on the editing room floor (inside your head).

Difficult is not impossible, and the risk is a balance between existing potential for harm, post-cleaning potential for harm, and the additional costs of either having unwanted warranty claims (something we can only speculate about as Keysight will certainly not release such commercially sensitive information), or additional costs of cleaning plus potential unwanted warranty cost as a result of more harm being done than good.

Yes, I understand very well, thankyou, nevertheless it's cosmetically unattractive, and in an instrument where I expect seriously anal levels of cleanliness, it does not sit well.

An observation isn’t an ad hominem attack.

I said that I guess you don’t open many devices, and that still remains a reasonable assumption, since your surprise at a bit of flux residue in a place where it clearly does no harm (because if it did do harm there, they’d remove it!) would have been tempered by seeing it in device after device. (Either that, or you have opened lots of devices but just haven’t been observant.)

[Kleinstein]

The added extra board looks like it not only contains some parts, but also acts as a bridge to bring one of the signals from one side to the others. It very much looks like the extra PCB was planed togehter with the updated main board.

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.
With the input signals routing needs quite some space for isolation and they may have just run out of board space in that corner and did not like a full redesign. The protection part on a separate board to simplify repairs may be an extra bonus.

The 34460, 34461, 34465 and 34470 are not that different. A combined board would make sense and should not take up more space. It should be mainly be a few parts missing with the 2 low end versions and maybe 1 or 2 bridges in the amps part to replace a relay or shunt.

[AVGresponding]

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.

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.

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? 

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.

An observation isn’t an ad hominem attack.

I said that I guess you don’t open many devices, and that still remains a reasonable assumption, since your surprise at a bit of flux residue in a place where it clearly does no harm (because if it did do harm there, they’d remove it!) would have been tempered by seeing it in device after device. (Either that, or you have opened lots of devices but just haven’t been observant.)

It isn't an observation, it's a subjective opinion expressed in a way to attempt to belittle the subject; you imply I am less experienced than you and therefore my opinion is of less value than yours. And you just did it again.


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.

[tooki]

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.

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.

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.

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? 

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.

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.

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]

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]

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.

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.

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.

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]

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.

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]

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.

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. 

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!

[floobydust]

Here is the TI EOL document PCN 20140630000 for the LM3S Tempest/Inferno defective MCU product line. Last shipments were through to end of 2015. We don't how much longer Keysight continued to produce H/W using the MCU. See end of doc but TI pegged the failure rate at 0.3% keeping down the costs of warranty credits Keysight surely received. There are no pin-compatible replacements.  Snippet of PCN last page:

Code: [Select]


July 1, 2014  Re: Acknowledgement and Limited Warranty Letter for Stellaris Tempest and Firestorm LM3S MCU Devices

Dear Ladies and Gentlemen:
Texas Instruments Incorporated (“TI”) has identified potential flash memory corruption risks with respect to the Stellaris Tempest and Firestorm LM3S part numbers listed in PCN 20140630000. You are receiving this Acknowledgement and Limited Warranty Letter (“Letter”) because TI records indicate you have purchased or sampled one or more of the LM3S Products affected. TI has made a decision to End of Life (EOL) these LM3S Products that were acquired from Luminary Micro. The Erratum (SPMZ861) for these LM3S Products is available at [url=http://www.ti.com]www.ti.com[/url].

TI did not undertake this EOL decision lightly. TI has undertaken significant diagnostic efforts and has replicated quality and performance issues, including flash corruption, that our customers have reported. TI has not been able to find any system level or manufacturing workarounds that completely prevent the flash corruption issues. Customer reported worst case fail rates for these LM3S Products, while using the entire flash in the largest 512kB configuration, is 0.3%. These issues may continue to manifest themselves as failures in customer designs over time, to a greater or lesser degree, depending on a customer’s system design, proportion of flash memory used, and storage times following a customer’s programming of the flash. Please see the Erratum for more details.

Importantly, we want to assure you that these reported flash corruption issues in the LM3S Products (which were designed using Luminary Micro methodologies) are not present in TI’s next generation TM4 products, which have been designed and produced in accordance with TI’s standard design and production procedures and methodologies. For the reasons explained herein, notwithstanding any provision to the contrary in any Purchase Order or any other purchasing or acknowledgement document, for shipments after September 1, 2014, TI’s sole and total warranty is a limited warranty. This limited warranty of credit or replacement is capped at .3% of the revenue for LM3S Products shipped after September 1, 2014.
When possible, TI will replace LM3S Products prior to the end of the EOL period based on then existing lead times. After completion of the deliveries at the end of the EOL period, this warranty will be limited to credit only. Except for this limited warranty, TI makes no warranty, express, implied or statutory, including any implied warranty of merchantability or fitness for a specific purpose, for these LM3S Products.
TI will not support full customer return analysis and any related corrective actions (8D reporting, cycle time metrics, etc.) for these LM3S Products, because of these known issues and uncertainty on how, or to what extent, these issues will impact actual customer systems. However, TI may, in its sole discretion, perform customer return analysis to verify warranty claims based on flash memory failures.
TI requires this Acknowledgement and Limited Warranty Letter for LM3S Products to be signed by you by September 1, 2014 to continue shipments after September 1, 2014.
If you desire further shipments of these LM3S Products, please have an authorized person sign below to indicate your agreement and acceptance of this Letter, and return a signed copy of this Letter to TI (at the e-mail address below ),or your authorized TI distributor, if you are buying from a distributor. This Letter will become effective upon your signature.
TI will accept cancellations of orders for LM3S Products accepted before July 1, 2014, if those cancellations are made by September 1 2014. Also, TI will accept returns of LM3S Products in customer inventory based on Return Materials Requests received by TI by September 1, 2014, that are undamaged and in original packing.
These LM3S Products should not be used for any safety-critical application in which a failure of the device could result in an injury to persons or property.
FOR CLARITY, PLEASE NOTE THAT ANY ORDERS REMAINING IN PLACE AFTER SEPTEMBER 1, 2014, WILL IMMEDIATELY BECOME NON-CANCELABLE AND NON-RETURNABLE. ANY INVENTORY REMAINING IN PLACE AFTER SEPTEMBER 1, 2014, WILL IMMEDIATELY BECOME NON-RETURNABLE, EXCEPT FOR THE LIMITED WARRANTY ABOVE.
Please do not hesitate to contact your TI representative or your distributor if you have questions.
Very truly yours,
Texas Instruments Incorporated


[bdunham7]

So anyone that shipped a product with it after mid-2014 was well aware that this defect existed?   

In some areas of the world, that would effectively extend your warranty to almost infinity for a consumer product.  Hmmmm.

[floobydust]

Apparently it's not a consumer product "... for professional and industrial use. They are not designed or tested for personal, domestic, or household use."
Who knows, legal might be eluding recalls and warranty extension this way, rights consumers would have.

[wraper]

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!

Chip revision does not matter. It's garbage by design, not some bug which could be fixed. Read pages 24-25 https://www.ti.com/lit/er/spmz861/spmz861.pdf?ts=1651046449928&ref_url=https%253A%252F%252Fwww.google.com%252F
Shortly Flash is trash by design and can corrupt data when left unpowered for a few months, but ECC is trash too and can read the data incorrectly and then re-program incorrect data  .

[salvagedcircuitry]

Chip revision does not matter. It's garbage by design, not some bug which could be fixed. Read pages 24-25 https://www.ti.com/lit/er/spmz861/spmz861.pdf?ts=1651046449928&ref_url=https%253A%252F%252Fwww.google.com%252F
Shortly Flash is trash by design and can corrupt data when left unpowered for a few months, but ECC is trash too and can read the data incorrectly and then re-program incorrect data  .

Boy, it looks like someone goofed. Sure makes the TI acquisition of Luminary Micro look like a million dollar pile of bricks! 

[floobydust]

TI desperately needed to leapfrog into ARM core or get left in the dust. But then taking 5 years to fully realize the 3rd party FLASH IP used in the MCU's is total garbage? I've only seem Atmel's SAM7 was a lemon randomly erasing its FLASH (had to give up and end that product) so maybe it's early Atmel tech Luminary bought. But LM3S FLASH just rots and ages even when sitting there doing nothing, so reprogramming the FLASH is not always possible or a fix.
Then, replacement parts are not pin compatible, so basically you chuck the main board into the garbage making for a very costly repair. It's a total turd. TI got suckered with that acquisition and Keysight mixing both ST and TI MCU's in a product not the brightest move.

[wraper]

TI desperately needed to leapfrog into ARM core or get left in the dust. But then taking 5 years to fully realize the 3rd party FLASH IP used in the MCU's is total garbage?

FWIW TI made ARM based SoC (mainly for phones) for at least a decade at the time of acquisition (2009).

[wraper]

Also it's not just flash that is garbage. Looking on errata it's easier to count things that are working properly, rather than those which are broken in some way.
For example following cannot possibly be overlooked. You need to make an informed decision to release broken garbage.

LM3GPIO#05 PB1 has permanent internal pull-up resistance
Device(s) Affected: Stellaris Tempest-class Rev C5 and Firestorm-class Rev A2
Description: Regardless of its configuration (GPIO or alternate digital function), PB1 has a maximum
internal pull-up resistance of 800 Ω that turns on when the voltage on the pin is
approximately 1.2 V. Due to this internal resistance, up to 3 mA of current may be
sourced during the transition from 1.2 V to 3.3 V.
Workaround(s): When this pin is configured as an input, the external circuit must drive with an
impedance less than or equal to 300 Ω to provide enough drive strength to over-drive the
internal pull-up and achieve the necessary VIL voltage level. Ensure that the driver can
sink the temporary current. In addition, do not use PB1 in open-drain mode.
If this pin is configured as an output, be aware that if the output was driven High and a
non-POR reset occurs, the output may be driven High after reset unless it has a 300-Ω
resistor on it. Once the pin is configured as an output, the pin drives the programmed
level.

[skander36]

Sorry for asking again, all 34465A DMM's make a relay click sound when central (red) wire is touched? It is a normal behaviour?
Thank you!

[wraper]

Sorry for asking again, all 34465A DMM's make a relay click sound when central (red) wire is touched? It is a normal behaviour?
Thank you!

Does it click if you disable autoranging? Also is it in 10Mohm impedance mode?