Keysight 34465A reliability

[alm]

annualized failure rate

[jonpaul]

Dear Daniel,

in case you are a Keysight afficanado or professional, can you please inform me...

I have a  new 34465a from Keysight in  August 2021,


serial  MY60016XXX

 FW A.03.02-03

Might it  have  the serious potential issues with the MCU, storage etc mentioned and is likely to fail eg if left un powered for  long periods?

Many thanks


Jon

[Traceless]

New units come with screws mounted. The holes were left for rack mount kits, but with screws in place the face is rock solid. Without the screws it feel a little loosy.
Also they seem that changed the TI MCU (TM4C1292NCPDTI3 - G4), and what that seem to be an electric switch with a jumper. (see pics)
And they used for 34465A boards marked 34460.

Thanks for the mini-tear down skander36, do you know the manufacturing date of your unit?

@KeithFisk: I'm sorry to hear that your unit failed do quickly I'd be curious to hear how the story ended, did Keysight offer any assistance despite the device being out of warranty. Did you repair or replace the device?

[skander36]

I wasn't able to find production date, but calibration was done in Nov.2021, so it is very likely to be in second half of 2021.
After finding that analog board MCU and also left side MCU from digital front panel have been improved, along with tightened of the front panel, now I am confident that major causes for fails that was reported have been addressed.

[Traceless]

I wasn't able to find production date, but calibration was done in Nov.2021, so it is very likely to be in second half of 2021.

I think your estimate is correct. AFAIK Keysight has a policy that devices that have been stored >6 months need to be sent back to KS (at least if you bought from an official KS partner). Thanks for taking the time to report back its good to know that devices manufactured >=Q3/2021 now use different hardware and thus may not be affected by the issue.

[KeithFisk]

@KeithFisk: I'm sorry to hear that your unit failed do quickly I'd be curious to hear how the story ended, did Keysight offer any assistance despite the device being out of warranty. Did you repair or replace the device?

@Traceless: I have asked the service agent to go ahead wit the repair but have no expectation of any concession or discount on parts and labour from Keysight.

[skander36]

AFAIK Keysight has a policy that devices that have been stored >6 months need to be sent back to KS (at least if you bought from an official KS partner).

Then there is a chance to be older than I have estimate. Calibration count is 75. I didn't know what that mean.
For me seem to be assembled unde the pressure of component crisis. (Keysight anounce 20 weeks delay for 34465A in Europe.)
I said that because it use 34460 board with a bridge under the main board. Maybe this is a solution for switching to rear terminals as the 34460 is not equiped with rear terminals. I am not sure though, maybe is just an improvement.

[HighVoltage]

That does not look like Keysight quality!
Not even cleaning the solder spots?

[skander36]

I don't know what to say. It is assembled on Malaysia on the same fab.
Those spots are where the mini doughter board is connected on the main board, maybe a rework?

[HighVoltage]

That definitely is a rework and looks like it was done by hand.

What is the part number and revision printed on the main PCB?

[HighVoltage]

I have just opened up my 34465A and took a few pictures.
This 34465A is in perfect condition and has worked well for many years already.

No extra PCB and no hand soldering anywhere.
The main PCB number is: 34465-26501 REV 004 KEYSIGHT MSS-B


Maybe you got a prototype of a new generation?

[skander36]

duno ... maybe @Keysight DanielBogdanoff  know 
The boards looks identical except components from pic attached (with red) that was moved onto the daughter board. Does not seem to be a prototype.
Also I am not sure if they changed Flash chip. Actual one that is used is Winbond as can be seen(attached).
Can you compare it with one from your DMM?

[TheSteve]

I would guess that the design was changed so that a single main board could be used with all versions, 34460 to 34470.

[Traceless]

@Traceless: I have asked the service agent to go ahead wit the repair but have no expectation of any concession or discount on parts and labour from Keysight.

Thanks for reporting back. If you have your device back and don't mind sharing I'd also love to hear what they charged you. Based on SteveyG's experience the problem seems to be no isolated case, just in case anyone else here runs into the same problem knowing the exact repair cost in advance would be interesting.

[Smith]

Small update, I now know why my transformer from the 34465A was fried. There was a dead short on the frontpanel, one of four 10uF 1206 caps was shorted. After I replaced it I luckily had the mains meter on it. The frigging thing took 120W, instead of the normal 11-12W from the socket. Even while it was turned off. Never had anything fry a transformer because of something so stupid. But there is a solution, I've ordered a Keithley DMM6500 to replace this crap.

[alm]

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?

[tooki]

That definitely is a rework and looks like it was done by hand.

Nothing about that says “rework”. It’s a later PCB version where they decided, for whatever reason, to move components to a daughterboard. Since that adds cost (both for the extra PCB, but also the labor required to connect the daughterboard), they’ll have done it for some significant reason.

Soldered by hand? Probably, but not necessarily: it could also have been robotic soldering. Either way, it’s done with a soldering iron rather than wave or reflow soldering. (Yes, robotic soldering with a soldering iron is a thing.)

[AVGresponding]

But apparently cleaning up flux residue is not...   

[tooki]

It’s extremely common to find flux residue around hand-soldered (or robot iron soldered) components on boards that were otherwise wave or reflow soldered. It’s common on connectors and on assembly that isn’t just a single board.

This is a totally normal thing, yes, in commercial products.

[AVGresponding]

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

[wraper]

Yep, often it makes more sense to use hand or robot soldering in production. For example when TH soldered on top side of PCB as in this case, or some other case where wave soldering is difficult to do or not justifiable from economic standpoint. For example if you just need a few contacts soldered, hand soldering is faster and cheaper.

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

Why it's not OK? There is nothing wrong with this. As of flux, if it's not some low leakage circuit where flux may cover unwanted gaps between the traces, other than cosmetics there is no reason to clean it. Also cleaning it is no so straightforward as it may seem. Simply cleaning it with IPA will spread the flux all around and probably under SMT components where tiny leakage current actually matters. And getting rid of so there are no visible signs of its presence will take order of magnitude more time than soldering that connection.

[AVGresponding]

It's a high-end meter, not a home-made blinky; I'd expect better.

[wraper]

It's a high-end meter, not a home-made blinky; I'd expect better.

You'd be surprised. But as devices become more expensive and produced in lower numbers, the amount of bodges goes up. In this case it's not even a bodge.

[AVGresponding]

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

[skander36]

But apparently cleaning up flux residue is not...   

Keysight is not known for making perfectly clean PCB's.
This are the PCB from DSOX2002 - flux on the bottom of the board. Maybe they keep the boards as the laundry dries on the wire