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

[Jidis]

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

wiggling the range switch would cause the reading to change

I coincidentally started getting the same thing not long ago on my Vichy LCR meter. It would give me crazy readings that I knew weren't anywhere near the right values. It took me a while to figure out it was from the switch. Seems like mine somehow doesn't quite land on the notches and I can usually flip it a couple spaces and back to fix it. If it gets worse I'll go in and clean it like you did.

I never liked those stupid rotary dials they all use, but I guess it's the most cost effective way of handling that many lines. At least Cen-Tech used a separate power switch to save a bit of wear on the dial.

Take Care

[momaka]

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... so I cleaned the range switch and power switch with alcohol... 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.

Nice!

I might try that as well. I also have to wiggle the range dial back and forth on all of my 830 meters to get a good reading. I think the worst one I have is my oldest DT-830D (not from HFT), which doesn't have an ON/OFF button, but rather you have to rotate the range dial to the OFF position every time. Being nearly 15 years old and used quite a bit, I bet those contacts are either dirty or plain worn now (or both?).

At least Cen-Tech used a separate power switch to save a bit of wear on the dial.

Yes, I like that feature as well. Also, if you use a certain setting a lot, you can leave the dial on that and not have to turn it every time. For me, it is the 10A current range - every time I supply power to a LV electronic circuit I built, I always monitor the current.

[Jidis]

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

Also, if you use a certain setting a lot, you can leave the dial on that and not have to turn it every time.

Yeah, that's why I'm not into the ones without a separate switch. Seems especially risky with stuff (like the Cen-Tech) that you already know isn't of the finest build quality to begin with.

For me, it is the 10A current range - every time I supply power to a LV electronic circuit I built, I always monitor the current.

I think for this particular meter, mine would probably be the 20V DC range. Oddly enough, I actually use it to set voltages on my benchtop power supply which has it's own meters (the analog style).

BTW, it would be cool if the crappy contacts are the main reason for the Cen-Techs being off in that low resistance range. Seems to be one of the main gripes you hear regarding its accuracy. I've got one of those small calibrated reference boards, and I think my two Cen-Techs were also only noticeably off in that one area.

Take Care

[momaka]

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

Guess what folks?

My old DT-830D was starting to act up quite a bit on the resistance and continuity settings. So today I tried what lti did in post #20.

And you know what? IT WORKS ABSOLUTELY 100%!
lti, you are a genius, man

Now my old DT-830D measures all the way down to 0.2 Ohms (on the lowest resistance setting) when I short its leads. And even if I wiggle the dial, it won't go above 0.4 Ohms. That is a HUGE improvement. Before, I had to wiggle it to get it down to 1-2 Ohms. Now, it is like brand new... or maybe even better .

I guess my HF meters will be next in line for that.

BTW, it would be cool if the crappy contacts are the main reason for the Cen-Techs being off in that low resistance range.

I think that really IS the reason why they measure resistance off. I mean, my old DT-830D was worse than bad - I'm talking about being off by as much as 100 Ohms on the 200 Ohm scale if the dial wasn't set "right". And now, it is perfect.
Unbelievable how much difference a piece of paper towel, some IPA, and 5 minutes of time can make.