Yeah ... it is from autoranging
When disabled no more clicking ...
Thank you very much @wrapper!
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TI/Stellaris LM3S1D21 ARM processor is discontinued 2016 and withdrawn from the market due to the flash corruption issues.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.
In the meantime I had a rather in depth email exchange with Keysight support (without needing to pay or jump through hoops). It looks like Keysight has found the issue with the LM3S1D21 by themselves and reported back to TI. According to Keysight they did some kind of check on the part to see if it is affected before assembly so units in the field shouldn't be affected. In case there is a problem, it shouldn't result in bad/wrong readings. The latter is my main concern.
If my unit where affected, it would have shown by now as it is sitting switched off for periods lasting over a year.
In the meantime I had a rather in depth email exchange with Keysight support (without needing to pay or jump through hoops). It looks like Keysight has found the issue with the LM3S1D21 by themselves and reported back to TI. According to Keysight they did some kind of check on the part to see if it is affected before assembly so units in the field shouldn't be affected. In case there is a problem, it shouldn't result in bad/wrong readings. The latter is my main concern.
If my unit where affected, it would have shown by now as it is sitting switched off for periods lasting over a year.
It's not like that. If you read the errata, you'd know that sitting off for years does not necessarily cause the NAND corruption. It just increases its chance. Staying always ON does not help with corruption either since of garbage ECC circuit which may cause corruption of good data by itself. The flash corruption rates given in ERRATA because of both issues are similar. It's not like there are good chips and bad chips, there is a crappy design.
Is there anyone on the forum who had a problem with the processor in the 34XXX series and after replacing everything was back to normal? I am asking because I have the opportunity to buy a 34461A which, when turned on, only illuminates the LCD and nothing else works. When opened, you can see that the SPEAR320-S2 is very hot.
It's now 2024 has this problem been resolved with current production KS3446A DMMs?
Bought a few yres ago, screen had intermitten blank fail.
Keysight replaced with a new uint, calibration cert IN WTY.
Apart from that , 100% perfect.
Jon
It's now 2024 has this problem been resolved with current production KS3446A DMMs?
From my email exchange with Keysight, it looks like they are using a different microcontroller as the microcontroller they used initially has been discontinued.
As I understand it, the self-destruct feature was mainly due to:
(A) Luminary MCU on the main board self-corrupting flash memory (Note 1)
(B) STM SPEAR320 processor on the front panel failing for some reason, at least some get very hot to touch
(C) NAND FLASH on the front panel getting corrupted, sometimes recoverable by interaction over the serial port.
Keysight is the undisputed champion of FLASH corruption, perhaps not always their fault but certainly early firmware made a poor job of recovering from FLASH corruption. e.g. depending entirely on one copy of the NAND ONFI parameters, ignoring backup copies when primary failed
My hope (I say staring at my DMM) is that these problems have been fixed in newer dark colour meters. Certainly the main board and front panel processors have changed, we have to wait and see if there are reports of NAND corruption on these newer meters. So far, so good on my bench
Note 1: TI EOL document PCN 20140630000 for the LM3S Tempest/Inferno defective MCU product line gives estimated failure rate of 0.3%
I had a fair share of NAND corrupted Keysight scopes.
But even with so many Keysight DMM 34461A, 34465A and 34470A I never had a problem with those.
Maybe the problem is larger, if these instruments are not used on a regular basis?
are they still running an WinCe thingy intheses, WinCe was notorious to wear flash memories because of too many read and write, you had to do some optimisations
many systems uncompress the wince boot file into memory, i had problems with systems who booted from some sd cards, it took a while to get a good brand
not bashing, but i'll thrust more an 34410a or 34411a way before thoses models
We have 3 KS34465As, one tan and two dark cased, nary a problem with any!!
Best,
Well, they certainly do fail, my 34461A (2018 light colour) is currently whitescreen mode, fail to boot. Also, a quick search of the forum showed up these failures:
analogRF 34461A fail to bootdc101 34461A fail to bootkanzler 34460A fail to boot晓看风云 fail to boot 34461Ajonpaul 34465A intermittant boot / black screen300DT fail to boot 34461A hot SPEARmaxtorque 34461A fail to bootelcal fail to bootautorepair78 34461A fail to boot hot SPEARyuhar fail to boot hot SPEARNandBlog random rebootsSmith fried transformer due to shorted capKeithFisk hot SPEARTheSteve seen several failed SPEARSteveyG "We've had 5 out of 12 purchased in 2019 fail the same way at work." (34465A hot SPEAR) skskelwl white screen fail to boot hot SPEARTERRA Operative fail to bootCharos fail to boot hot SPEARFixed_Until_Broken fail to boot 34461A hot SPEARrolkinas fail to boot 34465A hot SPEARkkayser fail to boot 34461AOf course, if you're not a company Keysight will say you have no warranty, even though you can buy from Farnell and no one will mention that. Perhaps in that case Farnell would offer one year warranty, I don't know. I hope the dark colour units are going to prove more reliable. My advice to private individual purchasers would be only buy dark units, avoid older models on eBay.
OTOH I have a Keithley 2000 I purchased non-working from eBay. £15 for some new op-amps and JFETs fixed it. I can source most parts in that meter, including the eprom firmware and am very confident I could fix it if anything happened to it in the next 20 years. Keysight 3446x/70, hmm, not so much.