This is why you don't buy cheap multimeters.

[retiredcaps]

Re: This is why you don't buy cheap multimeters.

The second one I got is with the red switch. I picked it on purpose, since the first one I got had a yellow switch. Just wanted to see if there was any difference. When I have time / feel like it, I guess I will tear it apart and see it for myself as well.

It would be interesting to see the differences from modemhead's pictures at

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

[momaka]

Re: This is why you don't buy cheap multimeters.

The second one I got is with the red switch. I picked it on purpose, since the first one I got had a yellow switch. Just wanted to see if there was any difference. When I have time / feel like it, I guess I will tear it apart and see it for myself as well.

[larrymoencurly]

Re: This is why you don't buy cheap multimeters.

When I get a free Harbor Freight multimeter, I've always picked a model #98099 (yellow on/off switch), but last time I instead got a model #98025 (red on/off switch). When I opened it I thought it was better built because I saw a neon bulb for voltage protection, but it turned out to be a soldered-in fuse. The #98099 instead has a regular 0.5A fuse in a snap-in fuse holder.

[momaka]

Re: This is why you don't buy cheap multimeters.

^ Yeah, it's a bit annoying sometimes. But I am pretty used to it now.

I just bought a second cheap HF multimeter (actually, I didn't buy it - it was free with any other purchase just like the last one), and it has that problem too, depite being a slightly different build. Same crummy leads, though. They read 1.4 Ohms at best when shorted. But it works otherwise. Just another cheap meter to have for general low-voltage measurements (sometimes, I need several multimeters when I'm working on projects on my breadboard).

[lti]

Re: This is why you don't buy cheap multimeters.

The second thing you have to know is that the dial on these cheaper meters is... well... cheap. Even if you have it on the 200 Ohm setting, it may not be snapped-on perfectly. You will find that if you move it around just a bit, you may get a good connection and low resistance.

That's actually what's wrong with the meter I have. Turning the dial slightly can make the resistance vary from 0.5 ohms to 8 ohms with the leads shorted.

[momaka]

Re: This is why you don't buy cheap multimeters.

Any other ways to repair this kind of probes which always come with bad craftsmanship from the factories?

Given that new probes cost very little money, it doesn't make much economical sense to fix them. However, I often find it faster to fix my old probes than to buy new ones, so I always end up fixing them up when they need it.

Here's how:
Strip the insulation on the connector leads you cut off (that is, strip the top only, and strip until you see the metal connector).
Take the stripped ends of your probes and solder them to the metal connectors your just stripped.
Insulate with electrical tape, heat shrink tubing, or hot glue (or all three, if you like ).
Enjoy!

Once repaired like this, I suggest you don't use the probes to measure high voltage sources. Other than that, they should work fine.

[mariushm]

Re: This is why you don't buy cheap multimeters.

Go on eBay and buy some probes, they're 1$ or something like that.

A whole new 830D is 3-4$ on ebay.

Those probes are AWG18 when pigs fly. They're more like AWG20 or AWG22, they just have thick insulation to fool you into thinking they're better.

[LENOVO-A880]

Re: This is why you don't buy cheap multimeters.

Fixing UNI-T DT830D Leads

I need to ask some opinions from experienced members here to repair the defective probes that come with these meter. I had done some minor repair like re-soldering battery block clips, remove the crack and bad solder joints and reworked some of the old insulation wire wraps. Please refer to this link from my previous post [https://www.badcaps.net/forum/showpo...&postcount=52]

Finally it can boot up like normal again but now I need some ideas from members here to fix these defective leads appear to have a real 18AWG wire rated for 1000V [AWG_wires]. Then the loose connection at the end of the leads had been cut off so far [leads_connector]. So some soldering works need to be done to attach the probes back to the meter like the thumbnails [probes_cutoff] attached below. This meter also measures 0.5 Ohms with the leads shorted [meter_0.5Ohm].

Questions:

1. Should I remove the probes from the meter and replaced it with a decent set (shielded 4mm jacks). Where can I get a new 4mm shielded sockets?
2. Any other ways to repair this kind of probes which always come with bad craftsmanship from the factories?

[lti]

Re: This is why you don't buy cheap multimeters.

how about a foto of the meter?

They're in this thread.

[momaka]

Re: This is why you don't buy cheap multimeters.

Might need to grind the standoffs a bit to get the PCB to insert more pressure on the LCD screen's ribbon.

I just posted pictures of mine here:
https://www.badcaps.net/forum/showthread.php?t=39320

[retiredcaps]

Re: This is why you don't buy cheap multimeters.

WOW!
Was it really that bad?

Yes. Those pictures are unmodified and I did not attempt to repair/fix/modify the DOA meter.

I still have it and I think the reason it doesn't work is the COB isn't working properly. If I flex the pcb, some digits appear on the lcd. I have fixed a few other 830s that I received for free, but I never use them. It was a good learning and troubleshooting experience.

[momaka]

Re: This is why you don't buy cheap multimeters.

You don't need two probes to make a shorted connection.

Put the black probe jack in COM and then put the black tip probe in V/ohm and note your resistance measurement. Then do the same for the red.

+1

The stock leads are still pretty crappy, though, so even with just one of them, you will likely still get somewhat high resistance. As I mentioned, mine went down pretty low with high quality leads.

Also check the soldering quality of the pcb input jacks. As you can see on mine, it has stellar soldering from the "factory"...

https://www.badcaps.net/forum/attach...8&d=1275345583

WOW!
Was it really that bad?
Mine wasn't "stellar" either, but at least it had a fuse installed and no crappy jumper leads like that. This one truly deserves a hall of shame picture. Makes my 13 year old cheapo 830 look like a Fluke compared to this .

I'll post mine today in a new thread.

[Agent24]

Re: This is why you don't buy cheap multimeters.

As you can see on mine, it has stellar soldering from the "factory"...

https://www.badcaps.net/forum/attach...8&d=1275345583

Wow, I thought my Dick-Smith meter was an el-cheapo!

[retiredcaps]

Re: This is why you don't buy cheap multimeters.

There might be a loose connection in the leads, but I can't figure out where one might be.

You don't need two probes to make a shorted connection.

Put the black probe jack in COM and then put the black tip probe in V/ohm and note your resistance measurement. Then do the same for the red.

Also check the soldering quality of the pcb input jacks. As you can see on mine, it has stellar soldering from the "factory"...

https://www.badcaps.net/forum/attach...8&d=1275345583

[stj]

Re: This is why you don't buy cheap multimeters.

how about a foto of the meter?

[momaka]

Re: This is why you don't buy cheap multimeters.

This meter measures 0.9 ohms with the leads shorted, and low resistance readings vary. Sometimes it randomly adds about 5 ohms to the reading on the 200 ohm range. There might be a loose connection in the leads, but I can't figure out where one might be.

First, you need to make sure the connection inside the handles is solid (if it's not and if you tore the wires out before, you need to cut the handle close to where the probe needle is on the front and re-solder the wire to it again). Once it is, pour lots of glue in the handles so that the wire can't move inside. I usually do this with hot glue. It's not the best solution but it works for quite a while. When the glue starts to break or peel (takes a few months to a year of occasional use), I reheat it with hot air from my heat gun and it holds the wire perfectly again.

The second thing you have to know is that the dial on these cheaper meters is... well... cheap. Even if you have it on the 200 Ohm setting, it may not be snapped-on perfectly. You will find that if you move it around just a bit, you may get a good connection and low resistance. Also, with the stock Harbor Freight probes, my Centech meter measured 1.4 Ohms at the lowest. Removing them from the meter and jumpering the COM and Ohm/V/mA jacks makes the meter show close to 0.2 Ohms. So it's just the stock probes that are crap. The meter itself does okay.

If your multimeter is a bit off there is usually a variable resistor inside that is used to calibrate it. Perhaps give it a try when comparing results with another calibrated multimeter to get the readings matched?

I advise against doing that, unless the multimeter still shows a high resistance even with its COM and Ohm jacks jumpered. For the most part, these meters are properly calibrated from the factory. Just bad probes and craftsmanship that brings them down. Mine had quite a few minor, but annoying, things that needed fixing. After fixing them, I'll venture and say that it's a pretty decent general-use multimeter.

[chozo4]

Re: This is why you don't buy cheap multimeters.

If your multimeter is a bit off there is usually a variable resistor inside that is used to calibrate it. Perhaps give it a try when comparing results with another calibrated multimeter to get the readings matched?

i'll tell you for a fact, my lead-free solder is almost smokeless - the flux stays on the board.

My lead-free flux smokes a little bit from the heat if there is excess on the tip otherwise it doesn't smoke. I generally don't use resin core solder for my work and instead silver bearing solder so this paste is always handy. Surely it doesn't help that my soldering paste was manufactured in the early 19th century and contains zinc chloride. Though afterward I always thoroughly clean the board afterward of any and all residue.

[stj]

Re: This is why you don't buy cheap multimeters.

my advice is a bit hardcore - but i'v done it a few times now.

first throw the non-standard cables in the bin.
then get a decent set with shielded 4mm jacks.

then fit 4mm shielded sockets to the meter.

[lti]

Re: This is why you don't buy cheap multimeters.

I need to figure out how to repair the leads that come with these meters. The ones I want to repair appear to have real 18AWG wire rated for 1000V, and it's even UL listed (E187208). The jacks on this one from Harbor Freight are slightly smaller than standard banana jacks, so standard leads don't fit.

This meter measures 0.9 ohms with the leads shorted, and low resistance readings vary. Sometimes it randomly adds about 5 ohms to the reading on the 200 ohm range. There might be a loose connection in the leads, but I can't figure out where one might be.

[stj]

Re: This is why you don't buy cheap multimeters.

AVO is for museums.
and they are very expensive.