FlorenceFluke 8020A digital multimeter (1979)
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GeekProjects NewsHandheld Oscilloscope Meter Reviewed https://hackaday.com/2024/08/14/handheld-oscilloscope-meter-reviewed/ #oscilloscope #scopemeter #ToolHacks #Reviews
hackaday unofficialMustool Scopemeter Review and Teardown
There was a time when calculators became so powerful it was hard to tell them from little computers. The same thing seems to be happening now with multimeters. They now often have large screens and basic oscilloscope functionality. The specs keep getting better. While early cheap scopemeters were often relatively low frequency, many are now claiming bandwidths that would have cost quite a bit a few decades ago. A case in point is the Mustool MDS8207 which [IMSAI Guy] reviews and does a teardown of in the videos you can see below. It claims a 40 MHz bandwidth with 200 megasamples per second on a single channel.
The only downside in the claimed specifications is that the sensitivity isn't great given that the lowest setting is 500 mV per division. Then again for a meter that runs under $100, any scope function would seem to be a bonus. The meter does all the other things you expect a meter to do these days, such as reading voltage, frequency, capacitors, temperature, etc. The response time of the meter is relatively slow, but you can get used to that.
The scope portion uses the meter probes, so you won't have a proper scope probe. At higher frequencies, the meter had a little trouble triggering, but it did give you an idea of the waveform. After 30 MHz or so the amplitude reading was also a little suspect.
Sometimes, though, seeing the basic shape of the waveform is all you need. It is a shame the meter portion isn't a little faster because if you had a great $100 meter that also had a scope, that might be useful. But it wasn't bad -- it just seems like you can get a nicer meter for $100.
In the teardown video, you can see that there isn't much inside and nothing surprising. The fuses, though, are soldered in and hard to get to, so you probably don't want to blow the fuses.
The verdict? [IMSAI Guy] seemed to think the meter was OK. We've seen better scopemeters, for a little more. We've also seen adequate meters for a lot less.
[Kerry Wong] is Really into Scope Meters
If a combination multimeter and oscilloscope is on your holiday shopping list this year, you might want to have a look at some of [Kerry Wong's] recent videos on the subject. Over several videos he looks at -- inside and out -- an OWON HDS272S and a Hantek 2D72, both reasonably inexpensive entries in the field. Both instruments are similar and have a few variants depending on the frequency capability and the addition of a waveform generator.
There are several videos on the Hantek device that are a few months old, then some recent videos -- like the one below -- on the OWON device along with some comparison videos.
In general, it seemed like [Kerry] had a slight preference for the Hantek in some areas like the user interface and software options but concluded that the OWON has better performance both in the oscilloscope and signal generator. As meters, the OWN is a 20,000 count true RMS meter, but the Hantek is only a 4,000 count and does not have true RMS. We really enjoyed seeing both devices looking at the same signal side-by-side.
We had looked at [Kerry's] take on the Hantek awhile back, as you may recall. Cheap portable scopes have come a long way since 2016, you have to admit.
Cloned Memory Module Fixes Broken Scopemeter
Finding broken test gear and fixing it up to work again is a time-honored tradition among hackers. If you're lucky, that eBay buy will end up being DOA because of a popped fuse or a few bad capacitors, and a little work with snips and a soldering iron will earn you a nice piece of test gear and bragging rights to boot.
Some repairs, though, are in a class by themselves, like this memory module transplant for a digital scopemeter. The story began some time ago when [FeedbackLoop] picked up a small lot of broken Fluke 199C scopemeters from eBay. They were listed as "parts only", which is never a good sign, and indeed the meters were in various states of disassembly and incompleteness.
The subject of the video below was missing several important bits, like a battery and a power connector, but most critically, its memory module. Luckily, the other meter had a good module, making reverse engineering possible. That effort started with liberating the two RAM chips and two flash chips, all of which were in BGA packages, from the PCB. From there each chip went into a memory programmer to read its image, which was then written to new chips. The chip-free board was duplicated -- a non-trivial task for a six-layer PCB -- and new ones ordered. After soldering on the programmed chips and a few passives, the module was plugged in, making the meter as good as new.
While we love them all, it's clear that there are many camps of test gear collectors. You've got your Fluke fans, your H-P aficionados, the deep-pocketed Keithley crowd -- but everyone loves Tektronix.
#news #repairhacks #teardown #flash #fluke #memory #ram #reverseengineering #scopemeter