Keysight's new 34465A (6.5 digit) and 34470A (7.5 digit) bench multimeters

[HighVoltage]

Photos are up in the usual place for those who can't wait...
Teardown wise the 34470A is as good as you could expect it to be 

Thanks so much for the photos, Dave !

It seems the 34465A is the replacement for the older 34411A and
The 34470A is kind of the replacement for the 3458A.

[KedasProbe]

Photos are up in the usual place for those who can't wait...
Teardown wise the 34470A is as good as you could expect it to be 

Where is the usual place? 


Edit: Thanks

[HighVoltage]

https://www.flickr.com/photos/eevblog/

[6thimage]

The person that came up with the name "Digitize Mode" at Keysight should be fired.

Why do you think that?

Because it doesn't say anything about what is different in that mode, it's digitizing in all modes, that's what a DMM is supposed to do. "Measuring Mode" would say equally as 'much'.
 "High Speed Mode" for example would already mean something.

I can see your point, but calling it 'high speed' has its problems as well - as the data logging and digitising modes overlap in terms of measurement speed. I think they went with digitise to invoke images of fast digitising systems, in contrast to the slower, and more precise, data logging systems. But either way, firing someone for a name choice seems a little excessive.

[radioFlash]

Interestingly, the 34470A's reference is attached by an 8 pin header (https://www.flickr.com/photos/eevblog/16171847343/). On the 34465, you can see there are 4 additional unpopulated holes by the LM399 reference:

https://www.eevblog.com/forum/testgear/keysight's-new-34465a-(6-5-digit)-and-34470a-(7-5-digit)-bench-multimeters/?action=dlattach;attach=141295

[6thimage]

Interestingly, the 34470A's reference is attached by an 8 pin header (https://www.flickr.com/photos/eevblog/16171847343/). On the 34465, you can see there are 4 additional unpopulated holes by the LM399 reference:

https://www.eevblog.com/forum/testgear/keysight's-new-34465a-(6-5-digit)-and-34470a-(7-5-digit)-bench-multimeters/?action=dlattach;attach=141295

The 34465A and 34470A share the same board - look at the part number at the top of this image https://www.flickr.com/photos/eevblog/16765926266/.

I don't think there are any disadvantages of having the reference on a daughter board with a pin header interconnect. Putting a reference in a socket (i.e. the LTZ1000), rather than soldering it, is seen as being bad, as the stress on the pins affects the reference's output, but as there is a daughter board, that's not a concern. I'm guessing they went with this method, so that it is easier to thermally isolate the reference from the rest of the measurement board.

Edit:
Additionally, the 34461A board has the 8 pin header footprint - https://www.flickr.com/photos/eevblog/9090130444. With the board in the 34461A having a 34460A part number, it's pretty safe to assume that 34460/61As in the future will have the same board as the 34465/70A.

[radioFlash]

Good catch. Here's a comparison of the 34465A to Dave's photo of the 34470A.

[TiN]

If we can get firmware dump from 34470A, then some voltnuts could be able to upgrade their 34460/61's to 34470A for cheap (~$400USD, cost of LTZ reference, foil resistor and missing parts) since rest of hardware is same 

I made animated gif for your enjoyment with all three..

[EEVblog]

If we can get firmware dump from 34470A, then some voltnuts could be able to upgrade their 34460/61's to 34470A for cheap (~$400USD, cost of LTZ reference, foil resistor and missing parts) since rest of hardware is same 

Not sure if that's possible, but the 34465A to 34470A should be possible, just change the reference and firmware. Or if you were happy with the LM399 just change the firmware to get the extra digit.

[EEVblog]

For those that want the two images of the 34461A and 34470A I have shot and scaled to match, here you go:
https://farm9.staticflickr.com/8721/16765926266_d30679e9d1_o_d.jpg
https://farm8.staticflickr.com/7606/16584505777_201128fea6_o_d.jpg

[6thimage]

If we can get firmware dump from 34470A, then some voltnuts could be able to upgrade their 34460/61's to 34470A for cheap (~$400USD, cost of LTZ reference, foil resistor and missing parts) since rest of hardware is same 

Not sure if that's possible, but the 34465A to 34470A should be possible, just change the reference and firmware. Or if you were happy with the LM399 just change the firmware to get the extra digit.

There is no point in dumping the firmware - it is the same for all 4 meters (34460/61/65/70A). I'm guessing the model number is tied to the serial number, and is stored in an eeprom or maybe in the processor's internal flash memory.

I'm guessing it is theoretically possible to hack the 34465A into the 34470A as they share the same board. But this board is different to the one used in the 34460/61A, in a few small ways. Additionally, the 34465/70A have a temperature sensor near the front connectors for cold junction compensation, which the 34460/61A don't have.

[KedasProbe]

Hhmmm the hacking started already?
The first prize for 'upgrading' the firmware for 34465A to 34470A  is an extra digit on your display , don't forget the DIG option

If a serial stored in the device is the key for 70A or 65A then maybe the firmware has to be changed to swap the logic which serial is 70A.   (just an idea)

[babysitter]

The User and Service Manual claims that turning the screw that holds the metal shield in place changes calibration - did anybody confirm it yet?

[splin]

About that ARM processor on the bottom of the board.

http://www.ti.com/product/lm3s1d21

This product is being discontinued. Orders for life buy purchases are available

TI does not recommend using this part in a new design. This product continues to be in production to support existing customers. TI suggests designers consider TM4C12x as an alternative family or series of devices for use in new designs.

Ooops!

Splin

[6thimage]

About that ARM processor on the bottom of the board.

http://www.ti.com/product/lm3s1d21

This product is being discontinued. Orders for life buy purchases are available

TI does not recommend using this part in a new design. This product continues to be in production to support existing customers. TI suggests designers consider TM4C12x as an alternative family or series of devices for use in new designs.

Ooops!

Splin

Texas Instruments did that with the Stellaris range of microcontrollers a few years back - overnight, and out of nowhere, they discontinued their entire range.

[splin]

They just copied the errors from 1988.. could have been done better..
Obviously, they just transferred the old 3458A reference PCB to modern design / components.
Even the alternative positions for R4 and R5 are available.. for pimping to 65°C / 1ppm/yr.

What errors?
I'm not familiar with the 3458A reference, never opened one. But isn't it the ducks guts?
Do you doubt this can meet the claimed specs?
I was impressed with the plastic enclosure design and the separation of the driver transistor (for separate cooling?).

Hi Dave,
sure, this reference is something like the Holy Grale. We discussed that in the Ultra LTZ1000 blog intensively.

But anyhow, HP engineers originally designed this circuit to run on 95°C, also due to the required ambient temperature of 55°C.
That causes a higher drift than intended originally by LT: running on 65°C instead gives typically -1.. -2ppm/year, and other designs of 8 1/2 digit DMM, standards and calibrators use 45..55°C oven temperature for around 1..2 ppm/year guaranteed stability.


In this instrument, they could have used the LTZ1000, (non A), easily reducing the oven temperature by 10°C and increasing the stability by a factor of about 2, and maybe further down to 75°C by better thermal management, giving 3..4ppm/year for sure.

Obviously, the Keysight engineers did not want to create an improved circuit, which they would have to re-qualify elaborately.
That could also be true for the rest of the circuitry, where they may have copied the Multislope IV circuit and algorithm from the 34410/11.
Frank

Its probably more about protecting sales of 3458As or its replacement - the 33470A already has 8 1/2 digits resolution so there must be a limited market for a significantly more expensive 'true 8 1/2 digit' meter with an inferior reference. Ok, there are other reasons for buying a 3458A but an almost as good 34470A (for DC measurements at least) would make that decision harder to justify for many.

Splin

[kwass]

But anyhow, HP engineers originally designed this circuit to run on 95°C, also due to the required ambient temperature of 55°C.
That causes a higher drift than intended originally by LT: running on 65°C instead gives typically -1.. -2ppm/year, and other designs of 8 1/2 digit DMM, standards and calibrators use 45..55°C oven temperature for around 1..2 ppm/year guaranteed stability.

If this is the case, why is the fan needed for normal lab environments.  It seems to me the this 61a/65a/70a should work just fine without the fan.  Has anyone here just pulled the plug on the fan in their unit and run it that way?

[6thimage]

I was wrong about the model number being derived from the serial number, in the manual, under SCPI errors, there is this:

+821,"Controller and measurement board model numbers do not match"
+822,"Controller and measurement board serial numbers do not match"

So both the model and serial number are stored separately in two places. The controller here is referring to the front panel - so swapping displays will cause the multimeter to error.

Interestingly, there is also this error:

+820,"Model and serial numbers not restored"

So I think it is safe to assume that the model numbers are stored in at least three places across the two boards (likely twice on each board).

The main processor (the spear320) has a 32 kB boot-rom and an 8 kB sram. So I think it is unlikely the serial & model number are stored in there. The processor has a flash and ram chip above and below it. The serial/model might be stored in there but I'm guessing that it isn't - it makes more sense for that just to hold the windows ce image, as then a firmware update can't make the multimeter forget its identity.

The front panel has an NXP LPC932 - an 80C51 microcontroller with 8 kB flash, 768 bytes rom and 512 bytes eeprom. If I was designing this, I would have placed the serial and model in that eeprom (their are no other external memories on the front panel), as you could update the microcontroller's firmware without the eeprom data being lost.

With the measurement board, I think it is unlikely they would store the serial & model in the FPGA as it hinders firmware updates. There is the TI cortex-m3 on the bottom of the board, but for the same reasons as above, I think it is unlikely they would store them in there. So the question then is, where do they store serial/model and also where do they store the calibration constants? My guess is U904 in this image https://www.flickr.com/photos/eevblog/16171847343/ - it looks like the right size package for an I2C eeprom, and it has pins 2 & 3 tied together (suggesting they might be address pins). Unfortunately I can't find any details on it.

[6thimage]

But anyhow, HP engineers originally designed this circuit to run on 95°C, also due to the required ambient temperature of 55°C.
That causes a higher drift than intended originally by LT: running on 65°C instead gives typically -1.. -2ppm/year, and other designs of 8 1/2 digit DMM, standards and calibrators use 45..55°C oven temperature for around 1..2 ppm/year guaranteed stability.

If this is the case, why is the fan needed for normal lab environments.  It seems to me the this 61a/65a/70a should work just fine without the fan.  Has anyone here just pulled the plug on the fan in their unit and run it that way?

I asked this question to someone in the know and they said that the fan moves very little air in normal lab conditions, but ramps up when the internal temperature rises (I'm guessing PWM). They also said that the drop in accuracy between the 34461A and the 34460A (the cheapest model without rear connectors and a fan) was largely due to the lack of a fan - with the 60A varying if the side holes are blocked by the handle.

[TiN]

U904 looks like ATMEL 34 I2C EEPROM. And U101 on front board looks EEPROMish too. Maybe Dave can use his MiniProg for them 

[6thimage]

U904 looks like ATMEL 34 I2C EEPROM. And U101 on front board looks EEPROMish too. Maybe Dave can use his MiniProg for them 

I'd guessed that it was an Atmel eeprom, but I didn't recognise the code on it. U101 is not an eeprom - it is an RTC (on the left of it is a 32.768 kHz crystal). I'm not sure why Keysight (back when it was Agilent) decided to have an external RTC, when the main processor includes one.

Here is a table of what is on the 34461A's front panel:

U100	TI 2051b 2bm a4dj	Single power distribution switch <0.5 A
U101	ST M41T82R	I2C RTC with battery switch over
U102	Maxim MAX3232E	RS232 driver
U103	C6AF NZ04	Possibly a Fairchild part
U200		Unpopulated 8 pin
U201	ST SPEAr320S-2	Main processor, ARM926EJ-S core, <333 MHz, 32 kB embedded boot ROM, 8 kB embedded SRAM, crypto co-processor, touch screen interface
U202	SMSC 8710A	LAN8710A (microchip) 10/100 ethernet transceiver - has auto-MDIX support
U203	Micron NQ277 2TDI7	MT29F1G08ABADAH4 1 Gb (128 MB) NAND flash
U204	Micron D9LHR 2NHI2	MT47H64M16HR-3 1 Gb (128 MB) DDR2-667 333 MHz DRAM
U205	TI LC07A 26K C6EC	SN74LVC07A hex buffer/driver with open drain outputs
U300	TI 54140	TPS54140, 1.5A step down converter
U304	TI TPS 650701	Single chip power IC for battery applications - can charge Li-ion batteries & has a resistive touch screen interface controller
U400	ODN	Unknown sot23-5 package
U401	NXP LPC932A1FDH	80C51, 8k flash, 768B RAM, 512B EEPROM - used for the soft power button
U403	TI L393	LM393 dual voltage comparator

I have taken a few photos of my front panel (34461A) and combined them into this https://www.dropbox.com/s/3fjewu04suqs75r/front-panel.jpg?dl=0, which some people might find useful.

For comparison, this is radioFlash's front panel


The board is different on the left hand side of the battery - few passives & unpopulated footprints, but the logo has also moved which makes me wonder what is new that we can't see in this image.

[kwass]

I asked this question to someone in the know and they said that the fan moves very little air in normal lab conditions, but ramps up when the internal temperature rises (I'm guessing PWM). They also said that the drop in accuracy between the 34461A and the 34460A (the cheapest model without rear connectors and a fan) was largely due to the lack of a fan - with the 60A varying if the side holes are blocked by the handle.

On the 65a/70a the ACAL function should solve that problem nicely.  (I think that ACAL may have been added to the 60a and 61a too in the latest firmware.)

[HighVoltage]

(I think that ACAL may have been added to the 60a and 61a too in the latest firmware.)

Based on what I read so far, ACAL is only available on the 34470A model

[6thimage]

I asked this question to someone in the know and they said that the fan moves very little air in normal lab conditions, but ramps up when the internal temperature rises (I'm guessing PWM). They also said that the drop in accuracy between the 34461A and the 34460A (the cheapest model without rear connectors and a fan) was largely due to the lack of a fan - with the 60A varying if the side holes are blocked by the handle.

On the 65a/70a the ACAL function should solve that problem nicely.  (I think that ACAL may have been added to the 60a and 61a too in the latest firmware.)

I have a 34461A and a pre-beta version of the firmware - the 34460/61A will not have ACAL, its a 65/70A feature (I think it requires the hermetically sealed Vishay resistor).

[6thimage]

(I think that ACAL may have been added to the 60a and 61a too in the latest firmware.)

Based on what I read so far, ACAL is only available on the 34470A model

Have a look at the datasheet - 34465A supports ACAL.