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    The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

    Two months ago, I received coupons from HF, and one of them included this meter for free (with any purchase). Since I needed some other stuff from there, I went and also grabbed this digital multimeter. The unit I got is item # 69096.

    I didn’t really expect much, since even without the coupons, this multimeter is regularly sold for under $10.

    It’s a very plain 7-function multimeter: standard AC and DC voltage measurements, DC current up to 200 mA or 10A, up to 2 MOhms resistance, diode test, transistor hFE, and 1.5V/9V battery test. Note, however, that there is no continuity function (hence no buzzer either).

    Probably one of its better-thought features is that it has a separate ON-OFF button – or at least I like it better, since I can leave the dial on a setting that’s used the most and not have to turn the dial when I want to turn the multimeter OFF.

    Before tearing the multimeter open, I decided to test some of its capabilities. Upon trying to plug the probes in the multimeter, I noticed that they didn’t go in quite easily. The 10A jack was particularly stubborn – I couldn’t plug in the probe all the way no matter how much pressure I applied (and I didn’t want to apply too much as I didn’t want to break anything after all). I inspected the plugs on the probes, but they appeared fine. So most likely something was obstructing the jacks in the multimeter.

    Speaking of the probes, they appeared quite thin - but no less than the ones on my 13-year-old 830 multimeter. Same length, too. Even the handles were nearly identical, with the wires running through them and not held by anything at the end to prevent them from being twisted in the handle (which, over time will cause the wires to break away from the handles).

    Continuing with my tests, I dialed the 200 Ohm setting and turned on the multimeter. I got a “1” on the left side of the screen – a good sign so far. Next, I shorted the probes together with a 16 AWG jumper lead. The display showed “14”. I though, that’s a bit high, isn’t it? Then I picked up the multimeter and tried to turn its dial. All of a sudden, a dot appeared between the two digits, thus showing “1.4”, then disappeared again. A-ha! So the decimal point isn’t working.

    Next I tested a voltage on a battery and compared it to my other multimeters. It agreed, so I concluded that’s enough testing and tore it up .

    Build quality:
    With a half-working decimal point on the display and probes that didn’t plug in the jacks very well, it is clear that the build quality wouldn’t be great. But I’ll let the pictures speak for themselves. First, here is a shot of the solder-side:
    https://www.badcaps.net/forum/attach...1&d=1406841775
    Not too bad at first sight, it seems – and it really isn’t. However, note the small PCB that holds the jacks for the probes – it is held to the other board only with big, blobby solder joints. I can see a lot of potential (pun intended) for trouble there.
    The solder joints on the rest of the board are pretty blobby too. The fuse (missing in the pictures, because I removed it) is a standard glass fast blow fuse, rated for either 0.2 or 0.5A (I’m going from memory here). At least the battery wires are running through holes on the PCB and soldered properly. I highly dislike wires soldered directly on top of the PCB, so that’s one thing they did okay.

    Here’s another shot of the other side of the board:
    https://www.badcaps.net/forum/attach...1&d=1406841775
    Blobby solder joints aside, the solder mask and PCB looks clean. Not much to complain about here.
    Another shot – more blobby joints on the trimpot:
    https://www.badcaps.net/forum/attach...1&d=1406841775

    Plastic top with the LCD inside.
    https://www.badcaps.net/forum/attach...1&d=1406841775
    Although not visible on the picture, two of the screw standoffs that the PCB is mounted on were cracked. The pink tab on the LCD is what touches the contacts on the PCB to make the LCD work. It’s not soldered to the PCB, just held by pure pressure from the PCB. Not a very good design, IMO. I grinded the standoffs only a tiny bit, hoping that this would make the PCB make better contact with the LCD ribbon and thus get that decimal point working. I also put hot glue around the standoffs to prevent from further cracking and/or completely braking off. I’ve seen it before with cheap plastic cases, so I though I would do this as a preventative measure.

    And here is why the probes wouldn’t go all the way in the jacks:
    https://www.badcaps.net/forum/attach...1&d=1406841775
    The soldering of the PCB was so bad that some of it got in the barrel jacks. I grinded it away with a drill bit attached to my dremmel tool.

    Finally, I put some hot glue at the end of each probe handle where the wires enter it. This is to prevent the wire from twisting and pulling out of the plastic handle. I also put hot glue near the banana jacks on the probes. The plastic that they have that is supposed to prevent the wire from breaking doesn’t really do that good of a job. After a years use or so (that is, if the wires on the probes near the handles have not broken yet), this is the second most likely place where the wire will break and cause a loose connection. So adding something supportive and flexible there is a good idea.
    After all of this, I assembled everything together, and this is the final result:


    Decimal point working and the wires in the probe handles don’t twist and don’t feel like they are going to break off. I tried touching both probes again on lowest (200 Ohms) setting, and the meter still read 1.4 Ohms. Tried my own probes (home-made from thick banana jack wires – made by Pomona - that were thrown away by our university), and I got 0.3 to 0.4 Ohms – good enough for me. Also tried measuring some AC voltage at the wall to see if anything will explode, but was disappointed in a good way (nothing exploded ). The 200 mA and 10A settings worked fine as well. (Though I don’t recommend anyone to measure high currents with the stock probes. The high resistance in the probes will likely cause the wire to heat a lot. If I remember correctly, someone on BCN tested such probes and their wire melted with something like 6 or 7 Amps of continuous load).

    Overall thoughts
    If you get one of these multimeters and take some time to perform the quality control and small “tune-ups” yourself, then this makes for a very decent general-use multimeter (especially for the price I got it). Perhaps the only thing that I didn’t do that is worth doing is to drill holes in that small PCB that holds the probe jacks, desolder it from the main PCB, drill holes in the main PCB as well, and then re-attach everything with thick wires or flexible jumper leads. That way, there is no danger of the solder cracking, making the connection loose or broken over time. Also, I don’t recommend this multimeter for high current, high voltage measurements, because… well, it’s a cheap multimeter. That said, it probably is okay for the occasional line voltage measurement – but be careful and don’t leave it unattended. Most of all, open the multimeter as soon as you buy it and check it thoroughly if you will be doing measurements on high power lines.
    Attached Files
    Last edited by momaka; 07-31-2014, 03:39 PM.

    #2
    Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

    Boy the trace clearances between the input jacks look very small for 750VAC input, it should be at least 6mm.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

    Voltage Regulator (LDO) testing:
    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
    http://www.badcaps.net/forum/showthr...er+testing+cfl

    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
    http://s807.photobucket.com/user/budm/library/

    TV Factory reset codes listing:
    http://www.badcaps.net/forum/showthread.php?t=24809

    Comment


      #3
      Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

      Here is the old one I've been using. It was made when these meters were $3 without a coupon.

      This one has the same "Screw removal by qualified persons only" warning on the back that yours have. I guess that means you need an electrician or an engineer to remove the screws, but you can do anything you want to it once the screws are out. The front looks the same and has the same ranges (including the battery test).

      I did try removing the circuit board from this one, but the plastic tab holding the jack board in started to break. It's the only support the jacks have.

      The included leads are labeled 18AWG, but I don't know if they really are that large. The wire with thinner insulation in the second picture is 20AWG, and they look about the same. I don't have any way to measure the area, so the included leads might really be 18AWG. Looking at the diameter compared to another stranded wire isn't accurate at all.

      This one always adds 1.1 ohms to any resistance reading. I don't want to start screwing around with it unless I know I can fix that while keeping all the other ranges accurate. Voltage readings are slightly higher than the meter I normally use, but not as high as the measurements from the Fluke 289 I borrowed while repairing my monitor last year.
      Attached Files
      Last edited by lti; 07-31-2014, 08:18 PM.

      Comment


        #4
        Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

        Originally posted by budm View Post
        Boy the trace clearances between the input jacks look very small for 750VAC input, it should be at least 6mm.
        It's called built-in spark gap , made to protect the multimeter (but not the user or his/her property) from high voltage .

        I thought about adding hot glue between those traces as well, but I was too lazy to follow the traces on the rest of the board and there may as well be other places with potential (oh, the puns, ha ha ha ) to arc over. So I decided it's not worth the trouble - I'll just use the multimeter for low-voltage measurements and probably mostly resistance and low current.

        Originally posted by lti
        Here is the old one I've been using.
        Thaat must indeed be an older unit as you have more through-hole components.
        Surpisingly, you wire does seem to be the right size. If it has UL number, it probably is legit. Mine has nothing on it and is way too thin to be 18 AWG and 1000V rated.

        Originally posted by lti
        This one has the same "Screw removal by qualified persons only" warning on the back that yours have. I guess that means you need an electrician or an engineer to remove the screws, but you can do anything you want to it once the screws are out.

        So that means I need a qualified person to change my battery as well .

        Originally posted by lti
        This one always adds 1.1 ohms to any resistance reading. I don't want to start screwing around with it unless I know I can fix that while keeping all the other ranges accurate.
        It's a cheap meter. Just get used to that resistance and offset it from your measurements.

        When I had my 830 multimeter only (the old one, that is), I still managed to fix plenty of hardware - even stuff with short circuits. And that meter *usually* reads 2 to 4 Ohms at the lowest with its stock leads. (later on, I made new leads for it, and with those, I can go as low as 0.3 Ohms).
        Last edited by momaka; 07-31-2014, 09:25 PM.

        Comment


          #5
          Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

          Originally posted by lti View Post
          Here is the old one I've been using. It was made when these meters were $3 without a coupon.
          I see they cheaped out on the PTC (just below the main IC) with a 152 SMD resistor instead of a real PTC. On some of the cheap 830s that I have, they have an actual PTC.
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            #6
            Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

            Originally posted by momaka View Post
            Overall thoughts
            If you get one of these multimeters and take some time to perform the quality control and small “tune-ups” yourself, then this makes for a very decent general-use multimeter (especially for the price I got it).

            Most of all, open the multimeter as soon as you buy it and check it thoroughly if you will be doing measurements on high power lines.
            Nice review. Modemhead over at this site has a photo review.

            http://mrmodemhead.com/blog/gallery/cen-tech-92020-dmm/

            Unfortunately, the modifications necessary to make it usable like how you did is beyond most DIY members here who come for help. Most can't even use a multimeter properly much less take it apart.

            The one thing I never see mentioned in any of these cheap meter reviews is how potentially dangerous the user interface is. For example, in your picture, if the dial were 20VDC, the other end of the red dial points 10A. Since the dial is completely red except for that slope (to indicate the selection), it is possible to have a potentially dangerous situation depending on where the probes are plugged and what the user is trying to measure (parallel or in series) with no 10A fuse.

            The same goes for trying to measure AC and having the selector dial on incorrectly set on ohms. All the selector switch needs is a big white dot on it.

            PS. It was member tom66 who fried his meter running 5 amps through it. See

            http://www.eevblog.com/forum/chat/sm...a-cheap-meter/
            Last edited by retiredcaps; 08-01-2014, 12:18 AM.
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              #7
              Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

              I also hear a lot of people say these meters are good to toss in the car as an emergency meter. While that is a good idea, I can't see how the internal build quality, flimsy secondary pcb soldering, etc would survive the summer/cold, bumps, potholes, movement, jarring of sitting in a typical car glove compartment.

              My 830 probes fell apart literally just sitting in the kitchen cabinet unused.

              I should take one of my repaired 830s and toss it into the car as a test over the next 12 months?
              Last edited by retiredcaps; 08-01-2014, 12:31 AM.
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                #8
                Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                Originally posted by momaka View Post
                That must indeed be an older unit as you have more through-hole components.
                The date code looks like it was made 2006, week 22?

                I have one with through hole components. If I remember correctly, the 100 ohm resistor (R12) was open causing the 830 to display/measure 666V DC for a 9V battery. It took me a while to figure out the problem, but I learned a lot.
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                  #9
                  Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                  bin the small board,
                  drill the case,
                  fit decent sockets.
                  unfortunatly the sockets will cost half as much as the meter probably cost - but that's how it is.

                  Comment


                    #10
                    Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                    Originally posted by momaka View Post
                    Most of all, open the multimeter as soon as you buy it and check it thoroughly if you will be doing measurements on high power lines.
                    Also the meter leads. I was measuring an AC outlet, and when I pulled out the lead tips, one stayed in the socket, still soldered to its lead, but it's been fine ever since I applied some plastic solvent weld glue and pressed it back in. Ironically, I had just warned somebody to not use this meter with high voltage. OTOH the AC readings were within 1V of my Fluke 73's

                    The meter pictured has a dot indentation in its rotary knob, but other versions of this or the 98025 instead have an arrow indentation, and it seems the quality is worse with the test lead jacks because some wouldn't read below 10-20 ohms with the leads shorted together (I did scrape the tips and reseated the sockets), and with one sample the socket sank when I inserted in the banana plug.

                    I noticed that some samples don't have the aluminum shield in back or the coil spring that presses against it.
                    Last edited by larrymoencurly; 08-01-2014, 05:10 AM.

                    Comment


                      #11
                      Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                      Originally posted by momaka View Post
                      Surpisingly, you wire does seem to be the right size. If it has UL number, it probably is legit.
                      It is UL listed. The listing number is E187208 and the style is 1032.
                      http://database.ul.com/cgi-bin/XYV/t...548&sequence=1
                      Originally posted by momaka View Post
                      So that means I need a qualified person to change my battery as well .
                      If they're still using the crappy batteries from companies nobody has heard of, you'll be replacing the battery pretty soon. This old one had a Colorful brand "Original Super Great Quality" battery in it, which died while sitting with almost no use.
                      Originally posted by momaka View Post
                      It's a cheap meter. Just get used to that resistance and offset it from your measurements.
                      That's why I didn't want to mess with it. It's too cheap to mess with. When I short the leads, it shows 1.2 ohms for a couple seconds and then drops to 1.1 ohms.
                      Originally posted by retiredcaps View Post
                      I see they cheaped out on the PTC (just below the main IC) with a 152 SMD resistor instead of a real PTC. On some of the cheap 830s that I have, they have an actual PTC.
                      I noticed that a long time ago.
                      Originally posted by retiredcaps View Post
                      My 830 probes fell apart literally just sitting in the kitchen cabinet unused.
                      That's what happened to this one.
                      Last edited by lti; 08-01-2014, 09:00 AM.

                      Comment


                        #12
                        Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                        Originally posted by larrymoencurly View Post
                        OTOH the AC readings were within 1V of my Fluke 73's
                        The main IC in all these cheap 830 variations is some derivative/knockoff/clone of the Intersil 7106 which Fluke helped design/develop.

                        Gory details at

                        http://www.eevblog.com/forum/testgea...e-multimeters/

                        http://www.theamphour.com/180-an-int...d-meter-maker/
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                          #13
                          Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                          Originally posted by stj View Post
                          unfortunatly the sockets will cost half as much as the meter probably cost - but that's how it is.
                          In my case, that would cost infinitely times as much (since I got it for nothing) .

                          Meh, if I want a good meter, I would just buy one. There are plenty of good cheap meters on ebay if you don't mind getting something used. I got myself a Radio Shack one for $20 that normally sells for $80 new. It was near mint condition with original box and everything. I'm sure there are probably even better deals. In fact, I missed out on quite a few.

                          The real bottom line is: if you do a lot of electrical work, you should get a good multimeter.

                          Originally posted by larrymoencurly
                          Also the meter leads. I was measuring an AC outlet, and when I pulled out the lead tips, one stayed in the socket, still soldered to its lead...
                          Wow, not good!
                          Yeah, I didn't expect much quality when I got mine so I inspected as much as I could. Hot glue cures everything .

                          Originally posted by lti
                          If they're still using the crappy batteries from companies nobody has heard of, you'll be replacing the battery pretty soon. This old one had a Colorful brand "Original Super Great Quality" battery in it, which died while sitting with almost no use.
                          I don't remember what battery it came with, but anything should be better than Duracell Alkaline - those just bulge way too much. If the battery compartment is tight, it will break stuff. For this reason, I now stay away from Duracell Alkaline. And in general, if something doesn't need high power, I no longer get alkaline batteries. Cheap Carbon Zinc batts seem to have a much longer shelf life.

                          Originally posted by lti
                          That's why I didn't want to mess with it. It's too cheap to mess with. When I short the leads, it shows 1.2 ohms for a couple seconds and then drops to 1.1 ohms.
                          That's not too bad of a resistance, considering how crappy the wire is with the stock probes. I bet you would get 0.5 to 0.8 with good leads, which isn't stellar but certainly better.
                          Last edited by momaka; 08-01-2014, 09:23 PM.

                          Comment


                            #14
                            Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                            I had a couple of the HFT freebies and I think the major complaint I have with them are the probes, they fall apart too easily. I think the meter itself will survive. Some of the other HFT meters have much better probes however, but you can't expect much from the freebies.

                            The freebie meter also has a 1M-ohm input impedance. This is low by most peoples' standards but acceptable for noncritical use. It still beats my analog meters...

                            Comment


                              #15
                              Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                              Originally posted by momaka View Post
                              I don't remember what battery it came with, but anything should be better than Duracell Alkaline - those just bulge way too much. If the battery compartment is tight, it will break stuff. For this reason, I now stay away from Duracell Alkaline. And in general, if something doesn't need high power, I no longer get alkaline batteries. Cheap Carbon Zinc batts seem to have a much longer shelf life.
                              Even a Durasmell would have lasted longer. It might have lasted a while if the meter was constantly being used, but its shelf life wasn't very long.

                              Unfortunately, I can't get my parents to switch to another brand of 9V or AAA batteries. The Enercell AAAs I kept for valuable stuff like my calculator are getting old, and the Durasmell AAAs leak inside the package before it's even opened.
                              Originally posted by momaka View Post
                              That's not too bad of a resistance, considering how crappy the wire is with the stock probes. I bet you would get 0.5 to 0.8 with good leads, which isn't stellar but certainly better.
                              I don't think the resistance readings set much lower than that. Even one of those cheap leads gives the same resistance reading. Also, I discovered that the fuse (500mA) has 1 ohm of resistance, but it's only used for the current ranges. The current measurements seem accurate.

                              Comment


                                #16
                                Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                                For anyone interested in these things, I've been sticking some pictures in a thread over at EEVBlog (in addition to the ones already there). If you run into ones which aren't yet on there, it would be interesting to see what's inside. It looks like there's a decent range of board and build quality between them.

                                Comment


                                  #17
                                  Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                                  ^ Cool thread. I do have another one that I haven't posted yet, but I think it's a version that it has been posted before. When I get to it, though, I will post pictures here on badcaps, regardless.

                                  Comment


                                    #18
                                    Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                                    Hi momaka,

                                    It's starting to look like there might be good ones and bad ones to get, but they use the same model numbers (like DT-830B) for twenty different ones, so it might be hard to figure out. I wish we could get lti's yellow version. I just got a dead DT-830D (I guess that's what the "D" is for). I wanted to see it output a square wave. I may try to track down one of the yellow ones that have it, but who knows what I'll get.

                                    FWIW, the 830D was a black one with a removable battery compartment. Did NOT appear to be very well built and has no labeling on the PCB.

                                    Take Care

                                    George

                                    Comment


                                      #19
                                      Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                                      For fans of the 830 style meters, see these two videos.

                                      https://www.youtube.com/watch?v=P4-SGlHoZ80

                                      https://www.youtube.com/watch?v=lHrFIxZ423E

                                      Discussion over at eevblog.

                                      http://www.eevblog.com/forum/testgea...$5-multimeter/

                                      PS. In obvious reference to Dave's eevblog #66

                                      https://www.youtube.com/watch?v=qlA7-fh5nDQ
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                                        #20
                                        Re: The Cen-Tech LE830b 7-function DMM from Harbor Freight Tools

                                        After I last posted in this thread, it became more difficult to make low resistance readings. I may have mentioned in another thread that wiggling the range switch would cause the reading to change and the resistance measured with the leads shorted had increased to 7 ohms. About a month ago, I started to get random low battery warnings and bad voltage readings (like 1.4V with nothing connected and overload on the 20V range when measuring a AA battery), so I cleaned the range switch and power switch with alcohol. I noticed a lot of residue on the PCB. Note that the switch contacts aren't attached to anything, so it is easy to scatter them all over your table if you're a dumbass like me. Look at Mr. ModemHead's pictures here if you need to see where to place the contacts. There is a position for a sixth contact on the dial, so note that the two inner contacts are spaced closer together on the side with three contacts. After cleaning, the low battery warning doesn't appear and all measurement ranges work. I get 0.3 ohms when shorting the leads, even with the original test leads.

                                        Also, I measured the diameter of the banana jacks because I wanted to know why it was so difficult to insert any leads other than the ones that came with the meter. The 10A jack measured 3.83mm, the V/Ω/mA jack measures 3.85mm, and the common jack measures 3.77mm. The four other banana jacks I measured (two jacks on an older meter and the pass-through jacks on an old pair of test leads) were slightly larger than 4mm, ranging from 4.04mm to 4.17mm.
                                        Last edited by lti; 05-27-2015, 08:14 PM.

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