Keysight 34465A reliability

[KeithFisk]

I have a Keysight 34465A which has just died with a power supply related fault on the front panel control board. What should be 3.3V is only 2V so all that happens on power up is the fan runs and LCD backlight comes on. Before I offer up bodily parts to the local NZ agent in exchange for repair of this I'm interested in the experiences of others with the reliability of these DMMs.
I'm considering abandoning it and replacing with something else. The nearest equivalent 6.5 digit DMM of another brand that I can find is the Keithley DM6500. I originally chose the Keysight simply based on more prior experience (40+ years) with HP instruments than any other brand.

Thanks in advance for any thoughts
Keith

[HighVoltage]

From my own experience and from what I read, the 34465A is a very reliable instrument.

It would be interesting to find out, what is really broken on yours.

[jonpaul]

Bonjour. Sounds like failed PSU reg or perhaps shorted/overloaded bus.

1/ Recieved used 3365A 1 yr old last Aug, worked 12 hrs. Next turn on black screen. Not screen saver/off. Intermittent, banging case could temporarily fix.

2/ Contacted Keysight service USA, returned to factory under warranty,

3/ two days after, a brand  new unit received, with new CAL cert

4/  running perfect since Aug 2021.

Recommend to contact local Keysight service.

Bon chance


Jon PS:  Could use your dead  if we can figure how to ship to USA!!

[tautech]

The nearest equivalent 6.5 digit DMM of another brand that I can find is the Keithley DM6500. I originally chose the Keysight simply based on more prior experience (40+ years) with HP instruments than any other brand.

We have SDM3065X in stock for around $1200 NZ if you need a meter in a hurry.

[TheSteve]

I've seen a few of the 3446x series fail with a bad main processor. They typically get hot and drag down the power supply voltage. Generally they are quite reliable though.

[bdunham7]

I've seen a few of the 3446x series fail with a bad main processor. They typically get hot and drag down the power supply voltage. Generally they are quite reliable though.

That sounds like it might be the OP's issue?  Unless you are a full-time HPAK DMM repair specialist or work at Keysight, if you've seen two or more units with this issue I'd say that makes it a pattern failure of sorts.  Is there practical fix for this?  I'm guessing not...

[KeithFisk]

Yes, bad processor.  Service agent has reported back that it was sitting at over 100 deg C. Just waiting to hear back about availability of board before making the repair or buy something else decision.

Thanks for the replies
Keith

[SteveyG]

We've had 5 out of 12 purchased in 2019 fail the same way at work.

[KeithFisk]

Mine was purchased in early 2018 so out of warranty but probably had less than 100 hours powered on time. Perhaps if I had used it more it might have failed while still under warranty. The quoted cost of the repair including a recalibration is 60% of the cost or purchasing a new 34465A, 75% of the cost of a new Keithley DMM6500 and 130% of the cost of the Hantek 6 1/2 digit meter that you recently reviewed on your YouTube channel.  (All NZ price comparisons.) There is obviously a significant quality issue and once out of warranty it appears that Keysight don't give a toss. 

[kcbrown]

We've had 5 out of 12 purchased in 2019 fail the same way at work.

5 out of 12?!?

That means this is a consistent manufacturing issue that is worthy of a recall.  If Keysight doesn't perform such a recall and doesn't fix failed units for no charge (either of those actions would do), then they'll have basically lost any substantial justification for being regarded an A brand.

[KeithFisk]

We've had 5 out of 12 purchased in 2019 fail the same way at work.

Did Keysight provide an explanation for the fault and more importantly what they have done to stop it happening again?

[HighVoltage]

Mine was purchased in early 2018 so out of warranty

A few years ago, all warranties for all 344xxA DMM were extended because of the high voltage rating debakel.
So, there is a good possibility, that your DMM is still under warranty.
Or at least, I would ask Keysight to cover it under warranty and see what they have to say.

 

[HighVoltage]

We've had 5 out of 12 purchased in 2019 fail the same way at work.

They were all 34465A models?
That is ridicules!

[SteveyG]

All 34465As, but that's only because that's all we buy. They all got fixed, only notes were that the front panel PCB had failed if I remember correctly. The Keysight service van comes once a month for service an calibrations so it just all was handled through them with all the other equipment. Not had any issues since though.

[floobydust]

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.

Front Panel processor ST SPEAr320S-2 is obsolete as well, but I did not dig into its issues.

[nctnico]

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. 

[HighVoltage]

All in all these units have a ticking time bomb inside them. 

This is really bad news, if true. I have many of the 34461A in the field with customers.
Do we know when Keysight switched away from the LM3S1D21 microcontroller to a different one?

[Kleinstein]

I have a teardown photo (should be somewhere here in the forum) from an 34461, that shows a TM4C129 for the inbound µC. So chances are they have different versions. With the chip getting obsolete they kind of need to have a replacement. Given the problems I don't think KS would still use any NOS parts from an EOL buy.

There should be a flash checksum test as part of the POS. So flash corruption would likely be catched after power on. Ideally one would even get a specific error code for a checksum failure.
Chances are that the code for the actual measurements is only a small part of the code and a bad bit is more likely to cause a crash than a wrong result.

[hpw]

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.

Front Panel processor ST SPEAr320S-2 is obsolete as well, but I did not dig into its issues.

This rings me a bell 

Does this means also, that the Wave Generator Trueform models 335xx & 336xx uses equal processors?

Hp

[TheSteve]

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.

Front Panel processor ST SPEAr320S-2 is obsolete as well, but I did not dig into its issues.

This rings me a bell 

Does this means also, that the Wave Generator Trueform models 335xx & 336xx uses equal processors?

Hp

From memory they use a different processor part #.

[giovannirat]

If not already mentioned in the forum, there has been issued a service note for the 34465A regarding loose front panel (date 02/02/2022 )

[HighVoltage]

If not already mentioned in the forum, there has been issued a service note for the 34465A regarding loose front panel (date 02/02/2022 )

That is a weird service note.
The mounting of the front panel has not really changed in years.
If they have not made the mounting holes very large, I can not visualize how the front panel should come loose.

But then on the other hand, these 4 screws should probably have been installed since the early 34401A

[skander36]

Sad ... I just pull the trigger for Keysight 34465A, choosing between it and Fluke 8846A. Now it is too late to withdraw the order.
I just hope that the black case is not the only revision for the KS 34465A.





P.S. For those interested TME has now in stock Fluke 8846A at a good price for Europe. Though it is little outdated as display.

[nctnico]

For bench use I'd skip the Fluke 8846A and get the DMM6500 instead. Having some graphing / logging facilities on a bench DMM can be very handy at some times.

[skander36]

I have Keithley DMM 6500 from more than a year. It is better than 34356A in most respects and with 400 E cheaper!
I am buiyng KS for a "second opinion"    as Siglent SDM 3065X is already out of calibration after 3 years.