January 26, 2010
GOT A NEW OSCILLOSCOPE!
It's been 20 years since I bought a brand new scope. My trusty old Hitachi stills works good, but I thought maybe it was time for something with a few more "features". I researched all the scopes I could find for under $1200 and finally plunked down my money on a...
B&K Precision 2534 digital oscilloscope.
Here's my review.
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Ordering it was a breeze. $719.10 (plus tax & shipping) from Digikey. Digikey is always efficient and pleasant to deal with . I have only happy things to say about the good folks at Digikey. It shipped the same day I ordered it. UPS took 6 days (including a weekend) to get it here, but 6-7 days is standard from MN to CA so I've got no complaints about our friends at UPS.
The package arrived intact and I was full of excitement! A new 'Scope...WOOHOOO! I opened it up and at first glance the contents looked nice. It's pretty, it's shiny, and it has that "New Scope Smell". What more could I want..?
Well, here we go...
#1 - DIRTY LCD SCREEN. The first problem was immediately obvious. The window in front of the LCD display is absolutely filthy. It's not on the front where it can be cleaned, but on the back side of the glass where it's inaccessible. This is visible in the photo below. (edges between clean and dirty areas marked by arrows) It's a little hard to see in the photos, but it's horribly obvious in person.
The dark area on the screen with the grayish border at the top and left is NOT an illusion or reflection of something in the room. It is a *relatively* clean area of glass surrounded by absolutely filthy glass along 2 edges.
Now that I've had to look at it for a few days I think maybe it looks more greasy than dusty. What kind of careless slob would install such a filthy thing, and where is the QA department that's supposed to have a look before stuff like this goes in the box?
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Here's another photo.
The OUTSIDE of the glass has been thoroughly cleaned. All that greasy scum is on the back side.
This filthy window is 100% unacceptable and is reason to reject the scope even with NO other problems.
But wait, we're just getting started...
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#2 - NOISY COOLING FAN. The second obvious problem is the noise the cooling fan makes when the unit is cold. When the unit is first turned on when it's cold in the room (<50F), the fan will sometimes chatter and howl like mad and run very slow for the first 5 to 30 seconds. After a while it will suddenly quiet down and run at normal speed. I've seen this problem enough times on *old* equipment and I recognize the sign of failed bearings. On a brand new piece of equipment, this is not a good sign.
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#3 - THE 50% TRIGGER BUTTON DOESN'T WORK RIGHT. This might be a nice feature.. if it worked. Pushing the "50%" button is supposed to set the trigger level to 50% of the waveform amplitude. The problem is that it doesn't usually work. Sometimes it will work, but the rest of the time it sets the trigger level to 0% and the scope stops triggering.
Once it has set itself to 0%, repeated pressing of the button does nothing. However, if you manually set the trigger level to slightly above 0%, then press the "50%" button, it WILL usually work right the first time. If it gets pressed again, it will go to 0% again and stop working. This appears to be a software problem not hardware, so perhaps it can be fixed with a firmware upgrade (more on firmware upgrade later).
UPDATE: This problem seems to have gone away. At least for today. Maybe the firmware upgrade really did fix something? Or maybe it's only a problem on some settings? Or maybe it's just having a good day today. But it seems to work OK now.
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#4 - THE VERTICAL & HORIZONTAL SCALE KNOBS ARE FLAKY AND HARD TO USE. These are a pain. As you turn the scale knobs you can hear a relay click at each position as you change the scale. If you are very deliberate and cautious about turning the knobs and turn them at JUST the right speed, then they work pretty good. However, if you turn the knobs a little too fast or too slow then they often get flaky and jump all over the place. Sometimes moving a single step on the knob results in a bunch of relay chattering and the scale will jump several steps instead of just one. Occasionally it will even step in the WRONG direction while turning the knobs. Both of the vertical scale knobs and the horizontal scale knob exhibit this problem and it can make the scope rather hard to set to the desired gain or horizontal timebase setting without some fiddling. After a while you kind of get used to how fast to turn the knobs for "best results", but it's still frustrating.
I don't know if this is just a software problem that could be fixed with a firmware upgrade or if the encoder hardware behind those knobs just "ain't right".
Anyway, once again it's just not acceptable.
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#5 - THE VERTICAL & HORIZONTAL POSITION KNOBS ARE FLAKY AND HARD TO USE. This appears to be the same problem that the H & V scale knobs have. These knobs are very inconsistent in their behavior. Sometimes turning the knob moves the position very slowly and other times it moves very quickly. Sometimes the trace will even take a few steps in the WRONG direction while turning the knobs. It's got some kind of weird encoder problem. Whether it's a hardware or software problemI don't know
Inconsistant, frustrating, unacceptable.
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#6 - THE AUTOSET BUTTON IS USELESS. This should be called the "Scramble Your Settings" button. Pressing the "AUTO" button is supposed to make the scope analyze the input signals on both channels and automatically set the gain and timebase controls accordingly. The User Manual (which I've read cover to cover) gives some "rules" that autoset is supposed to follow... the required minimum voltages and duty cycles for autoset to work, and so on. The scope clearly hasn't read the User Manual and it has NO idea what the rules are. It just sets things seemingly randomly according to some demented set of guidelines that only it knows.
Pressing the autoset button guarantees that you will get to spend some time fiddling with the awkward and frustrating gain, timebase, and position controls until you can find your signal on screen and at a reasonable size again . ARRRGGH!
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There's other "minor" annoyances as well, like the way the trigger point goes off the screen to the left when the timebase is expanded instead of expanding the waveform to the right of a stationary trigger point. Or the "Holdoff" feature that sets a the minimum time between 2 trigger events. It works great, but the range is from 100nS to 2 secs, and to cover that range it seems like you have to spin the knob about a zillion turns or until your fingers fall off. I can't really say that these things don't work right. It's just makes it rather unpleasant to operate.
In fairness, mechanically the scope doesn't seem too bad. It seems pretty solid and the "feel" of the buttons and knobs isn't too bad. If the controls worked reliably and the window glass wasn't so horribly filthy and the fan didn't sound like an imminant failure item, I'm sure I could be happy with it...
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FIRMWARE UPGRADE - I did go to the B&K website and downloaded the most recent firmware for this thing. I followed the simple instructions and It loaded it into the 'scope with no problems. But alas, it did NOTHING to fix ANY of the problems.
UPDATE: The 50% trigger problem seems to be fixed now. It's possible the new firmware fixed it, or maybe it's just a coincidence.
The new firmware DID make the speed window in the top right corner of the screen act different. With the original firmware, this number was always constant at 400MSa/s, which is also the rating of the scope. After the firmware upgrade it now changes with the horizontal timebase setting, displaying a maximum of 40GSa/s with the timebase set to 2.5ns.
40GSa/s? Hmmm. Why does that seem unlikely? Sadly there's no mention of this displayed number in the User Manual, so I'm not sure what it's *really* trying to tell me.
ANOTHER UPDATE... 1/31: OK, so It seems that the 40GSa/s is "real". I'm guessing that the scope was in the "averaging mode" instead of "real time" mode, which would explain the very high sample rate numbers. I finally figured it out after reading the owners manual for a different brand scope, which explained it better.
The box SAYS it's been inspected. But I just don't think so.
And the picture of the garbage can with an "X' through it? They can't fool me on that one either.
I'm hoping that this was just a freak from B&K. Maybe this was a pre-production unit that somehow escaped the R&D lab. But whether it's just a freak or if it's typical quality... I don't want to know. I just want it off my bench and I won't be looking at any other B&K products anytime soon.
This one goes back where it came from and now the search begins for something else. What a waste of time.
Sigh....
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FINAL UPDATE: I returned this unit to Digikey and they inspected it and agreed it was defective. Digikey refunded my money plus return shipping cost. Thanks Digikey!
March, 2010. Got a Rigol DS1102Ca to replace the B&K. It ain't perfect, but it's good, and it works, and I like it enough to keep it. Here's the review of the Rigol.