Since the dismantling of a new digital multimeter, I finally discovered the secret of Keysight's success.

A few months ago we did an email interview with the Keysight Digital Multimeter team. Many classic products have been born in this star group from the HP era, such as the 3458A, 34401A and 34970A. For this team, the question we are most concerned about is: Why is the 34401A so successful, and what can they do after such a huge success?

This interview with us was Wayne H. Willis, who is the product manager for the multimeter team. This buddy joined Hewlett-Packard in 1979 and was the first to be responsible for the management of the production line. In his 1992 HP Journal, he published an article on how to use the VXI platform on an automated test line. It is said to be an avid computer enthusiast.

Photo of Wayne Willis on HP Journal

The interview was very interesting. In order to cooperate with the interview, we also secretly demolished their new 34461A digital multimeter. The content of the dismantling part is in the second half of the article, and you can check it with the Q&A section.

Yes, after interviewing Wayne, we also split one of their 34461A into this.

* In the following article

EEN stands for EENuts and WW stands for Wayne Willis

EEN: Please tell us about your work on the Keysight multimeter team. Can you show us the photos of the team?

WW: Hello, everyone, I am Wayne Willis, 34461A R&D Manager, and an Electronic Engineer. I joined HP in 1979 (38 years!). Every day, work with R&D engineers and product marketing engineers to design and develop new products. Because the focus of this interview is on our digital multimeter, I think I should post a photo of the design team. As you can see in this photo, our team consists of young engineers and senior engineers (or seniors) with more than 40 years of work experience. There are even several engineers who have participated in the 34401A project. Of course, you can easily identify these big names because they have less hair...

The 3446X multimeter R&D team took a group photo, and the engineers with less hair participated in the 34401A project ... Is this the fate of the electronics engineer? ? ?

EEN: Since the 34401A is the most successful product in the history of HP-Agilent-Keysight, did you have a special celebration when it officially announced that it was discontinued?

WW: Of course there are. In fact, we had a particularly big celebration and held a grand “retirement” ceremony for the 34401A, on the day it was discontinued (December 1, 2016). We looked carefully at all the people who worked in the 34401A project (including R&D, marketing and order management) and invited as many people as possible to attend. Of course, many of them have retired, so this event eventually became a reunion of old friends. The host of the event was the man who was responsible for the promotion of the 34401A market. He spoke a lot of fun pieces on the spot and relived the time with everyone. (A little touched, very strong human touch)

EEN: As a participant, from your perspective, what factors make the 34401A so successful, can you help us list the three most important reasons?

WW: In our time, the 34401A was a really different product. With a price of five and a half, it provides six and a half measurements accuracy and resolution, and its durability and reliability have never been surpassed in the industry. So its success is the result of a balance between low price, high performance, and ruggedness, which is exactly what users really need.

EEN: What super powers did you use at the time to make the 34401A so successful and enduring? If you want to design such a successful product, where is the difficulty?

WW: I think this may be due to the fact that the 34401A is HP's first product to conduct a massive market research before development. All market research results were aggregated into an analysis tool called House of Quallity (HOQ, which was the first product development decision system proposed by Japanese companies in the 1980s). We will Customer feedback is detailed and prioritized. The “quality house” system was a new thing at the time, but it turned out to be a very effective method, especially at the critical moments when trade-offs were needed. The first thing we thought of was to put the user’s requirements first. Bit.

For example, let's take an interesting example: we all know that for users, they all want our products to be particularly strong and reliable. On the one hand, we must find ways to improve product quality and meet their requirements. On the other hand, we should also find ways to make them very intuitive and feel that our products are particularly reliable. That's why in the final design of the 34401A, a rubber protective cover (bumper, which was not available in previous HP products) was added. To this day, all of our desktop instruments continue to wrap this rubber sleeve, and even affect other manufacturers, because this appearance strongly meets the customer's psychological expectations. (I feel being riddled...)

34401A without bumper, it looks really weak

Bumper's design is still widely used on today's benchtop instruments

The most difficult part of designing a successful product is the need to invest a lot of effort to balance cost, performance, and reliability. To meet these three requirements without sacrifice, you need to put a lot of effort into the details of the product, and also need a lot of innovation, collaboration and mutual support between the R&D team, the order management team and key suppliers. I am very happy that we have been doing well.

EEN: As a member of the 34401A project, is there a little bit of regret for you?

WW: No, not at all, it is perfect. (Proud face...)

EEN: We have seen that the Multi-slope ADC has evolved to the fourth generation on the 34461A, and what improvements have been made to this generation of technology. The new ADC system is still using a combination of multiple chips, and it is possible to make a single chip in the future to achieve this.

WW: We continue to improve A/D algorithms and techniques in our multimeters. The earliest multi-slope integration technique evolved into the second generation (3458A and 34401A) and the third generation (34410/11A). In order to balance resolution and speed in new products, the delta-sigma algorithm is used in the design of the ADC, which also gives the test results a better linearity. Precision ADC design requires the use of many devices (including reference levels and high-stability devices, matching resistor networks, high-impedance and matching low-leakage switching devices, A/D control circuits, etc.). High-level chip integration has been happening all the time, but we found that a single chip design can not meet all the accuracy requirements we need. Therefore, the current design is still based on multiple chips and devices. I believe that technology will continue to evolve, and it may not be long before a single chip can achieve all of our performance requirements (at that time the price will be cheaper).

The 34461A's fourth-generation multi-slope integrated ADC circuit part still uses multiple chip combinations.

EEN: We have noticed that in recent years, many electronic test and measurement companies have begun to talk more about applications and solutions. How should we adapt to this trend for general electronic instruments such as multimeters?

WW: It is true. For many of our products, the market will require us to adapt to more special applications, as is the digital multimeter. We have also chosen a variety of responses to this. First of all, it is very easy to add more features by upgrading the firmware. In addition, many products can be opened to install a special application function (a bit like Apps on the phone). Finally, we have been working on developing more software to match the instrument to meet more unique application requirements.

EEN: What are the key technological innovations of this 3446X series multimeter compared to the past products?

WW: The new digital multimeter uses a modified ADC design that allows us to achieve seven and a half digit accuracy and resolution at a lower cost and in a smaller footprint. The new generation of ADC design also enables us to achieve faster reading speeds. In addition, we have added Auto Calibration (ACAL) to our equipment (34465A and 34470A) to maintain high measurement accuracy under temperature and environmental influences.

As mentioned in earlier reviews, the 34461A, 34465A, and 34470A have almost the same design of the main circuit except for a few core components, which effectively reduces R&D and production costs.

In addition, thanks to the development of digital technology over the past 25 years, we are able to make better use of the excess computing power to do things that are not possible on the 34401A. We have ported many functions that have been implemented through analog circuits to digital circuits (such as the calculation of RMS values), resulting in higher reliability and stability, and the price is much cheaper. For example, FPGAs use it, and it takes on a lot of things that used to require a dedicated chip.

LATTICE's FPGA chip completes a large amount of computational work in multi-slope integration

EEN: The 3 446X series multimeter has changed a lot in the operation interface. How do you react? What are the benefits of the new UI for users?

WW: Everyone has a very good feedback on the new operation interface. It feels intuitive and can be used very quickly. The navigation menu makes it easy to find various functions (the 34401A panel has few buttons, so you need complex combo buttons to go through the layer menus to find the features you need). The measurement results can be displayed on a larger color screen, and we can now not only provide readings, but also graphically display statistical results. In UI design, we want to not only provide accurate readings, but also present results in a more intuitive way, improving their insight into measurement results. You can now see trends, histograms, statistics, and more, not just display readings, you can analyze the data more comprehensively to better understand the measurement results.

Display test results in a histogram on a large color screen to understand distribution characteristics

EEN: We saw a huge color screen and a new user interface on the 3446x series. In the future, are you planning to use more consumer electronics technologies such as touch screens or wireless connections on desktop instruments?

WW: We will continue to research new technologies, as long as they are reliable, reasonably priced, safe, and valuable to our customers, we will consider adding them to our product design. A recent example is that we implemented the MTP protocol on the USB communication interface on the back of the instrument, so that you can drag and drop data files from the instrument directly onto the PC just like a USB flash drive without writing a program.

The MTP function can directly read the test results in the multimeter memory via USB.

EEN: The reliability of the 34401A is an important factor in its success. For the new digital multimeter, what have you done with it?

WW: It's really hard to list the certification tests and "abuse" tests that our products have undergone during development. I can only talk about them in a broader way. It includes temperature/humidity limit testing, temperature cycling testing, mechanical abuse testing, input signal abuse testing, ESD testing, input transients and chopping testing. These are all necessary safety tests. For example, we recommend a working environment temperature between 0 and 55 ° C, but the actual ambient temperature used in the test is far beyond this range.

In addition, you must also consider some possible misoperations, such as an engineer who didn't sleep well the night before, accidentally loading 1000V large voltage directly into the resistance test function. Although this is a very dangerous operation, we have to guarantee It does not damage the meter.

Loading a large voltage of 1000V during the resistance test does not destroy the 34461A, but it is not encouraged to do so...

In addition, we also have the experience accumulated in the previous generation of products, this is a rich treasure house, let us refer to and learn, this information has made a great contribution to our final design decision, to ensure that we provide customers with reliable design.

EEN: Finally, what is the next product of your team? Is there a 34480A (the legendary eight and a half multimeter), or the new 34970A?

WW: Follow us, I think you will definitely like it.

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The interview ends here.

Next, let's take a look at the disassembly of the 34461A.

Look at it in the end is not reliable

The picture above is a complete disassembly of the 34461A, the process is quite sour. The most impressive thing is that there are very few screws used in the whole product (a total of only 6 screws, three of which are used to fix the fan and GPIB interface). The connection between the circuit and the housing is mainly locked by various buckles. Dead, so I was very brainburned when I disassembled the machine. Friends who like to play toys can challenge themselves with the 34461A. This design is very convenient for later installation and maintenance, and it also reduces the chance of the screw rolling into the machine to cause a short circuit.

Readers who have read the 34401A article before will find that the 34461A maintains the same design style as the 34401A, and the hardware layout is even more concise.

Top view of the 34401A

Top view of the 34461A

In the process of dismantling, the first place to get stuck is how to separate the main board from the front panel. We spent a full hour here. Finally, it was found that there is a T-shaped black buckle on the red test lead connector (below), which is the only fixing piece for connecting the front and rear panels to the main board. Just pull it out hard and you can easily remove the front and rear panels. If the clip is not removed, the front panel and the motherboard are firmly locked together.

The main board and the front and rear panels are connected without screws, but a clip is used to lock the two together.

The motherboard and front panel that were finally stripped open, the middle is the buckle

It is also worth noting that the 34461A main board and the front panel are connected by the connector inside the yellow circle of the above figure, and on the 34401A, a gray data line is additionally used. The assembly of the 34461A is obviously more convenient, just on the line.